摘要:

MAY, 1909. Vol. XXXIV., No. 398. THE NEW STANDARDS FOR SEWAGE EFFLUENTS. BY S. RIDEAL, D.Sc., F.I.C., AND W. T. BURGESS, F.I.C. (Read at the Meeting, L4pr.il 7 , 1909.) THE Royal Commission on Sewage Disposal, appointed in 1898, has, after more than ten years’ labour, issued its Fifth and main Report (ANALYST, 1908, 33, 443-447). The portion of this document which is of particular interest to analysts is that relating to tests for sewage effluents in relation to standards, and no apology is needed for submitting a short paper on this important subject to the Society of Public Analysts. Recognising that the settlement of differences concerning effluents, etc., between local authorities and manufacturers by appeals to the courts was often costly and unsatisfactory, the Commissioners early recommended the creation of a new Govern- ment Department---a Central Authority-which should be clothed with full powers to conduct inquiries and give decisions on such matters.The constitution and duties of the proposed Central Authority, which the194 THE ANALYST. Commissioners suggested might conveniently be made a new Department of the Local Government Board, were outlined in the Third Report, issued in 1903. Frequent references to the Central Authority are made in the Fifth Report, and with regard to standards the Commissioners state (paragraph 319) : ‘‘ Power should be conferred on the Central Authority to suspend, from time to time, the operation of any standard, to allow time for construction of works, or for any other reason which in their opinion justified such suspension.” In May, 1903, the Commission sent out a circular letter to chemists and others on the question of standards, and obtained replies.Witnesses were also examined, and experimental investigations carried out. As a result of all this the Commissioners report (paragraph 320) : “ The experiments which we have already made show that the mere estimation of the amount of organic matter in an effluent does not by itself afford a sufficient index as to the effect which that effluent will have on any stream into which it may be discharged.” Farther on (paragraph 321) the Report states: “According to our present knowledge, an effluent can best be judged by ascertaining, first, the amount of suspended matter which it contains, and, second, the rate at which the effluent, after the removal of the suspended solids, takes up oxygen from water.” Consequently, no arbitrary standards based on proportions of oxygen consumed or albuminoid ammonia are suggested by the Commissioners, and instead the Report (paragraph 322) proceeds : “For the guidance of local authorities, we may provisionally state that an effluent would generally be satisfactory if it complied with the following conditions : “(I) That it should not contain more than 3 parts per 100,000 of suspended matter; and- “(2) That, after being filtered through paper, it should not absorb more than- ‘‘ (a) 0.5 part by weight per 100,000 of dissolved or atmospheric oxygen in twenty-four hours ; “ (6) 1.0 part by weight per 100,000 of dissolved or atmospheric oxygen in forty- eight hours; or- “ ( c ) 1.5 p a & - by weight per 100,000 of dissolved or atmospheric oxygen in five days.” The Commission is to be congratulated on this new departure, and we have now to measure the liability of effluents to change under what approaches to some extent natural conditions.The natural oxidation of organic suspended matter is also some- thing that has to be reckoned with in discharges from all sewage works, but we do not here propose to discuss the question as to whether it is or is not desirable to eliminate suspended matters from effluents prior to laboratory aeration tests. I t is obvious that chemists at sewage works, and analysts who hare to deal with effluents, will now supplement their ordinary analyses with such tests as will ascertain whether their effluents do or do not conform to the above standards.Another question presents itself: Are two or more chemists, operating with the same effluent in different laboratories, likely to obtain identical results from their several new tests? I n reply, we may here state that, in our opinion, agreement is extremely improbable unless strictly uniform methods of analysis are adopted.THE ANALYST. 195 As one of the supplements to their Fourth Report, the Commission issued a special report by its chemists on “Methods of Chemical Analysis as Applied to Sewage and Sewage Effluents,” and one naturally turns to this publication to ascertain the details of the methods of analysis favoured in the Commission’s laboratory. For suspended solids, direct determination, by filtration through prepared asbestos in a Gooch crucible, is recommended. Exact directions are given, and there should be no difficulty in chemists obtaining uniform results.The method works well, but we have sometimes found it useful to use two small crucibles instead of one large one. For dissolved oxygen two methods are given : 1. The colorimetric process devised by Sir William Ramsay and Miss Homfrey (ANALYST, 1902, 27,104). 2. Winkler’s method as modified by Ridertl and Stewart (ANALYST, 1901, 26, 141). However, neither of these methods is suggested for use in connection with the new standards ; and as regards the carrying out of ‘‘ the dissolved oxygen test, or aeration test, as it is sometimes called,” the Report refers UE to Appendix VI., containing a long and interesting report by Professor Letts and Dr.Adeney on the pollution of estuaries and tidal waters. Herein we find the description of an apparatus invented by Dr. Adeney, “by which the rate of absorption of oxygen, as well as the total amount of oxygen taken up, can be readily measured.” A drawing of this apparatus, together with an abstract of Dr. Adeney’s communication to the Royal Dublin Society, has already appeared in the ANALYST (1909, 42), and it is consequently unnecessary to reproduce it here. We procured several forms of this apparatus (which the dealers were instructed to make from the descriptions in the reports), and, having examined and tried the device, we thought that it was not likely to find favour with most chemists.The contrivance is all right in theory, but one of our chief objections to it was the very practical difficulty of insuring that no movements of the corks or leakage of air took place when the apparatus was shaken-an operation which the instructions state is necessary from time to time. The early forms of the apparatus not being satisfactory in our hands, we thought it desirable to make experiments with a view to simplifying a chemical method for estimating dissolved oxygen in water. Hitherto it has been usually the castom to express dissolved oxygen in cubic centimetres per litre of water, but in this paper all results are expressed in parts per 100,000, and for convenience of reference we append a table, expressed in this way, giving the amounts for saturation at temperatures from 0” to 30” C.Anyone having had experience with Winkler’s process can form a fair idea of the condition of aeration of a water from the depth of tint of the iodine liberated on the addition of the acid alone, without titration with thiosulphate; and a long time ago we had recognised the possibility of a colorimetric process based on the iodine tints. We have now modified Winkler’s process into a colorimetric method which will give fair results even in the presence of nitrites, and it is applicable to find sewage effluents in most cases.196 THE ANALYST, TABLE GIVING THE AMOUNTS OF DISSOLVED OXYGEN IN DISTILLED WATER AT VARIOUS TEMPERATURES FOR AN OBSERVED BAROMETRIC PRESSURE OF 760 MM.* Temperature, c. Oxygen in Parts per 100,000.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1-42 1.39 1.36 1.32 1 -28 1-24 1.22 1.19 1.17 1-14 1.11 1.09 1-07 1.04 1.02 1 -00 Temterature, C. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Oxygen in Parts per 100,000. 0.98 0.96 0.94 0.92 0.90 0.88 0.87 0.85 0 84 0.82 0.81 0.80 0.80 0.79 0.78 In Winkler's process, as is well known, the water under examination is treated with a small volume of MnCI, solution, and then with NaOH and KI ; the whole of the dissolved oxygen almost immediately reacts with the manganous hydrate, and when the latter is dissolved in HCI, iodine corresponding to the amount of dissolved oxygen is liberated. We have found that the iodine tints given by waters under this treatment are strictly proportional to the amounts of dissolved oxygen, provided that a fair excess of KI has been used.In order to construct a series of colour standards corresponding to various pro- portions of oxygen, by increments of 0.1 part, from 0 to 1-5 parts per 100,000, it is convenient to use 3 or 4 ounce square-shouldered stoppered bottles of nearly colour- less glass. Out of about four dozen bottles obtained in one delivery from the dealers, we had no difficulty in selecting eighteen to twenty of uniform height and having approximately the same capacity. The selection had an average capacity of 131.5 C.C. (measured completely full), and those above or below this did not vary by more than about 1.5 C.C. Of the selected bottles, those not used for standards were marked and reserved for making the tests in. The standards can be prepared in the follow- ing manner: Into fifteen of the bottles run 90 C.C.of distilled water (free from organic matter), 1.5 C.C. of 10 per cent. KI, and 0.15 C.C. conc. HCl. The iodine tints can be very easily obtained by running into the series of bottles the calculated quantities of a standard solution of potassium permanganate. The ordinary solution used in water analysis (0.395 gram per litre, 10 C.C. =0.001 gram oxygen) is most convenient for this purpose. For example, the 131.5 C.C. bottle requires 13.15 C.C. of the solution * The figures from 5' to 30" C. have been calculated from the table given by Roscoe and Lunt (Trans. Chem. Soc., 1889, 569) ; those from 0" t o 4" are based on estimations by Winkler's process.THE ANALYST. 197 to produce an iodine tint corresponding to 1 part of dissolved oxygen per 100,000.In this way the set of standard colours, from 0.1 to 1.5 parts of oxygen, can be readily made. The proper amounts of permanganate having been run in, the bottles are filled up with distilled water, except for a minute bubble of air, the stoppers tightly inserted, and the contents mixed by agitation. Iodine is, of course, liberated from solutions of HI when they are exposed to strong light, but if such solutions are kept in the dark they suffer little change. The iodine standards should therefore be kept in a box, provided with a number of little compartments, and comparisons should only be made in diffused light, the standards being replaced in their dark case immediately after use. We have found that such standards may be relied on for over a month.(The liability to change may conveniently be checked by noting when sensible colour begins to develop in a " blank " containing distilled water, KI and HC1 only.) The water to be examined is siphoned with care into one of the test-bottles, 0.5 C.C. of nearly saturated MnCl, solution added, and then 1.5 C.C. of a solution containing 30 per cent. NaOH and 10 per cent. KI. The stopper is inserted, and the contents well mixed. After the oxidation of the mangauous hydrate has taken place, and the precipitate has settled down somewhat, the stopper is withdrawn, and 1.5 C.C. conc. HC1 added. The stopper is then re-inserted, and the contents of the bottle well mixed. As the reaction with the acid causes a slight elevation of temperature, and consequent expansion of the liquid, the stopper has zt tendency to get loose, and it is convenient to plunge the test-bottle in a large basin of cold water, and to turn it about until the stopper is tight again. After wiping the bottle, the tint of the liberated iodine is compared with the standards, and it is best to do this by holding the bottles in an inclined position a few inches above a white card, and looking down through their shoulders. After a little practice there is no difficulty in estimating the fractions between the standards to within 0.03 part of oxygen.The following figures show the degree of accuracy which may be attained by the colorimetric process : DISSOLVED OXYGEN IN PARTS PER 100,000. By Iodine Standards.0.03 0.35 0.67 0.79 0.85 0.90 0.92 By Titration. Winkler's Method. 0.03 0.32 0-62 0.81 0.83 0.86 0.92 By Iodine Standards. 1.00 1.07 1.07 1.10 1.14 1.30 1.35 By Titration. Winkler's Method. 1.02 1.04 1.06 1.10 1.10 1.28 1.37 The above figures cover practically the whole range of the solubility of oxygen in water, and it will be seen that the colorimetric determinations did not differ from the titration tests in any c a ~ e by more than 0.05 part.198 THE ANALYST, The interference of nitrite with Winkler’s ordinary process is well known, but may be obviated by the modification described by Rideal and Stewart (ANALYST, 1901, 26, 141). In the colorimetric process, however, the disturbance due to nitrite is definite, and can be allowed for. Under the test, when a water contains nitrite, there is no trouble through NO acting as a carrier of oxygen, as the reaction of the nitrite, iodide, and acid takes place in a solution from which the free oxygen has been already removed by the manganese hydrate.The iodine liberated on account of nitrite is consequently that of the ordinary equation : 2NaN0, + 2KI + 4HC1= 2NaC1+ 2KCl+ 2 N 0 + I, + 2H,O. I t follows that for 2 atoms of nitrous nitrogen we have to allow for 1 atom of oxygen. In other words, if a water contained 1.4 parts of nitrous nitrogen, the iodine liberated on that account would correspond to 0% part of oxygen. The correction for nitrite is, therefore, easily arrived at. Below we give a few figures illustrating this point : PARTS PER 100,000. Nitrous Nitrogen.0.87 1.08 0-65 0.87 043 0.09 Oxygen Equivalent of Nitrous Nitrogen. 0.50 0.62 0.37 0.50 0.25 0.05 Dissolved Oxygen. By Iodine Standards. / \ Not corrected for Nitrite. 0.54 0.81 0.67 1.03 0-81 0.64 Corrected for Nitrite. 0.04 0.19 0.30 0.53 0.56 0-59 By Titration with Thiosulphate (no Nitrite present). 0.03 0.20 0.32 0.51 0.56 0-61 The experiments were made on waters quite free from colour, and they show that if the proportions of nitrite are estimated and allowed for, they do not vitiate the colorimetric process. We have now to discuss the subject of the determination of dissolved oxygen in sewage effluents. The Commission’s recommendation is that the effluents should be filtered prior to estimating the amounts of oxygen which they will absorb in from one to five days.I n the first place, it is unlikely that the effluents will be fully aerated at the time of collection, and, except in cases where the laboratories are at the works, there will usually be a considerable interval of time before the examination can be started. On arrival at the laboratory the effluents may be expected to contain less oxygen than at the time of collection; on the other hand, an uncertain amount will be introduced during the operation of filtration. With regard to this matter we have made a few determinations, the oxygen content of the waters and effluents in the first place being reduced by either heating or by agitation under diminished pressure.THE ANALYST, DISSOLVED OXYUEN IN PARTS PER 100,000. 199 Softened chalk water ... ... ...... Thames water (Hammersmith at low water) Effluent from land ... ... ... ... Effluent, mixed land and bacterial ... ... 9 , 1 , 9 ) 9 1 $ 9 9 , ... ... ... ... ,, 9 , 1, ... ... Befere Filtration. 0-25 0.32 0.32 0.1 4 0-14 0-14 0.14 After Filtration. 0.53 0.59 0.62 0-79 0.71 0.63 0-56 Taken up during Filtration. 0.28 0.27 0.30 0.65 0.57 0.49 0.42 The filtrations were made through plain and folded filters, about 20 cm. diameter, and the tests were conducted as rapidly as possible. As might be expected, we see from the above that by mere filtration a considerable fraction of a part of dissolved oxygen may be added to an effluent, and it is obvious that this must have considerable influence on the subsequent dissolved oxygen tests. No precise instructions appear to be given in the Commission's publications, and if uniformity amongst analysts is to be secured, we must come to some definite understanding as to the time an effluent should be kept (possibly a day) before fhe analysis is commenced, and after filtration we must insure full saturation by agitation with air, the temperature being, of course, noted.In regard to aeration, we have made a considerable number of experiments on waters and effluents of different kinds, and we are quite satisfied that good agitation for two minutes in a bottle half filled with liquid will insure normal saturation with oxygen at any temperature or pressure likely to be met with in a laboratory; and this is as true for liquids that are supersaturated before agitation as it is for those which are deficient in oxygen at the start.We may therefore feel sure that if we know the temperature and barometric pressure at the time of agitation, reference to a table will give the amount of dissolved oxygen without the necessity of actually estimating it. In applying the colorimetric process to effluents for the purposes of the new standard tests, we proceed in the following manner : About 1-25 litres of effluent is filtered and aerated by agitation with air, and the temperature of the liquid noted, and if the barometric pressure is much above or below the normal, it is as well to record that also. Three stoppered bottles, A, B, and C, of 250 C.C. capacity, are completely filled with the filtered aerated effluent and tightly stoppered. The remainder of the filtered effluent is mixed with an equal volume of distilled water, agitated with air for two minutes, and the temperature noted; two more 250 C.C.bottles, D and El are completely filled with this mixture.* This set of five bottles will be more than sufficient to ascertain whether the effluent will or will not pass * If the filtered effluent exhibits cloudiness of a character likely to interfere with the colour-tests, we prefer to use larger bottles and to resort to the ordinary Winkler method, where little or no nitrite is present, and inother cases, t o the modification of Rideal and Stewart, which is adapted to admixtures with trade effluents.200 THE ANALYST. the new tests. I n the cases of the undiluted effluent we have about 1 part of dissolved oxygen available for absorption, and with the diluted effluent about 2 parts of oxygen. During the five days the bottles should be kept at a nearly uniform temperature-say 15' C.-otherwise it will be impossible to obtain concordant results. Indeed, we have noticed very considerable differences in the rates of ab- sorption of oxygen over the range of temperatures which may occur in laboratories. At the end of twenty-four hours a test-bottle is completely filled by means of a siphon with undiluted effluent from bottle A, and its stopper inserted.As effluents usually have some colour, it is desirable to compare the tint with distilled water in a, similar bottle, and also with weak iodine standards corresponding to 0.02 and 0.04 part of oxygen. I n this way a correction for the colour of the effluent may be arrived at.The reagents are then added, and the tint of the liberated iodine is immediately carefully compared with the standards. The nitrite is estimated (pre- ferably by the meta-phenylene-diamine test), and the oxygen equivalent of the nitrous nitrogen calculated. The corrections for the colour of the effluent and the nitrite are deducted from the main reading, and the result gives the proportion of dissolved oxygen in the effluent after standing twenty-four hours. The difference between the saturation figure for the temperature at which the effluent was aerated and the figure given in the test is, of course, the amount which has been absorbed in twenty-four hours. The undiluted effluents in bottles B and C are similarly examined at the end of forty-eight hours and five days, and if these are still found to contain a fair proportion of oxygen, it will be unnecessary to examine the diluted effluents in bottles D and E.(The loss of oxygen in the diluted samples must, of course, be multiplied by two.) With ordinary care very little oxygen is taken up during the transfer of water from one bottle to another by means of a siphon. The siphons we use are made of glass tubing, internal diameter 5 mm. to 6 mm., and the longer limb is cut and joined by a piece of rubber tubing which does not restrict the flow, and which may be pinched with the fingers to stop the siphon. By repeatedly transferring the same water from one bottle to another we have found that, with moderate care, the increment of oxygen due to a single transfer is about 0.01 part when the liquid is only about one-quarter saturated, and the error is much less when dealing with half- saturated waters. In actual practice it is hardly necessary to determine the nitrous nitrogen more than once, as we have not noticed sensible variations in the amounts present at the ends of the one, two, and five day tests-at any rate in the cases of effluents which do not absorb the whole of the dissolved oxygen.As the nitrite does not usually change, it is possible to work in another way. The samples immediately after aeration may be treated with the reagents in a test- bottle and compared with the iodine standards; the oxygen reading will be a little high, owing to colour of the effluent and the iodine liberated through the nitrite present.The excess due to colour and nitrite will be practically the same in the samples after standing the definite times ; consequently the differences between the direct readings against the iodine standards give the absorbed oxygen in parts per 100,000.THE ANALYST. 201 We give below the results of analysis of a few effluents, together with the figures obtained in the oxygen-absorbed tests : PARTS PER 100,000. Total solids . . . ... ... Suspended matter, total . . . Suspended matter, volatile . . . Suspended matter, non-volatile Ammonia, free ... ... ... Ammonia, albuminoid . . . Oxygen consumed from perman- Three minutes at 26.7' C.. . . Four hours at 26.7" C. ... ... ganate : Nitrogen as nitrates . . . ... Nitrogen as nitrites ...... Chlorine ... ... Dissolved oxygen absorbed in twenty-four hours . . . ... Dissolved oxygen absorbed in forty-eight hours . . . ... Dissolved oxygen absorbed in five days ... ... ... ... ... Effluent from Land. 64.1 Less than 3 - 0.58 0.26 0.65 1.09 0.015 6.1 0.3 0.8 1.4 Effluent from Land. 86.4 Less than 3 - 0.53 0.075 - 0.65 1-61 0.04 7.1 Nil 0.04 0.28 Effluent from Bacterial Treatment. 70.3 Less than 3 - - 0.95 0.13 1 a38 2.73 0.02 6.7 Nil 0-30 0.72 Effluent from Bacterial Treatment. 59.4 4.40 2 98 1.42 0.22 0.17 0.89 2.23 1.95' 0.03 5.5 0.02 0.06 0.22 In conclusion, vre venture to hope that the colorimetric process for oxygen out- lined in this paper will be of service to chemists at sewage works, and analysts who have occasion to examine many effluents.DISCUSSION. The PRESIDENT having invited discussion, Mr. RAYMOND Ross said he had to examine something like 2,000 samples of sewage effluents per annum, always more or less against an authority, so that in his case the question of agreement between analysts was one of paramount importance. There was this to be said for the titration process-that it was very simple ; but in any test he should object to filtration of the effluent before testing it, because he considered that it did away with one of the strongest points in favour of double contact treatment. It must be admitted that the sprinkler method of treating sewage resulted in a much higher content of nitric nitrogen, but it also, without subsequent straining, resulted in a much larger deposit, and, owing to the rapidity of the purification, more oxidisable matter was left in the effluent.A greater demand was therefore made on the nitric nitrogen and, if the nitric nitrogen were not sufficiently abundant, on the dissolved oxygen. If all the sediment likely to make any demand on the nitric nitrogen or on the dissolved oxygen were filtered off, the effluent was202 THE ANALYST. not tested with complete fairness. He thought that an effluent ought to be tested in the condition in which it was delivered into the stream. The object of purification was that which was turned into the stream should not cause a nuisance in that particular stream, having regard to the purposes for which it was to be used. If it was to be used only for condenser water, the same degree of purification was obviously not necessary as would be required if cattle were to drink from the stream.From the purely nuisance point of view, he was strongly of opinion that, if it could be shown that a stream was not being polluted to an extent that was objectionable for the purposes for which the stream was likely to be used, that should be the standard for that particular district. The standard could not be the same every- where. I t seemed to him unnecessary to extend the determinations over so long a period as the Royal Commission recommended. If an effluent were shown to be not putrescent during a given short period-depending upon the time required to dilute it with a suficiently large volume of water to make it unobjectionable-and if the weirs in the neighbourhood were such that they did not fill up with deposited matter and so cause a nuisance, he,did not think anyone had a reasonable right to as& for any further purification.Mr. SEYLER said that he was pleased to find that Winkler's method stood so well the tests to which it had been put by the authors. He should like to hear whether it was equally satisfactory when applied to waters containing suspended matter, or whether some modification, such as preliminary oxidation with per- manganate, as suggested by Dr. Rideal, would be necessary. The importance of the temperature of incubation was illustrated by the low results obtained with a sample taken during cold weather. He had experienced a similar difficulty, and was inclined to choose some temperature that could be readily obtained all the year round-for example, about 25" C .Mr. J. H. JOHNSTON said it seemed to him that, at the stage at which the colour reaction was made use of, the end of the process had practically been reached ; and as there were many cases in which, owing to colour, opalescence, etc., titration must necessarily be resorted to, why not titrate in every case? What was the particular advantage that the authors claimed for their method? His practice was never to filter the effluent. In those effluents in which it was worth while making the test the suspended matter settled out readily, and a portion could be siphoned off for the determination with practically no suspended matter in it. I n this way less error was introduced than by filtration. Mr.Ross desired to add that, as had been several times pointed out-first, he believed, by Mr. Moor-& high proportion of nitric nitrogen with a good percentage reduction in albuminoid ammonia was sufficient to insure protection against undue pollution. For instance, in Lancashire there were a large number of slop-water closets, the sewage being, therefore, very strong, and the same standard could not be hoped for that would be possible in a town where fresh-water closets only were used. When, however, strong sewage was treated by any of the usual methods, probably everything readily oxidisable in it, or likely to cause any nuisance in the stream, was oxidised, whereas weak sewage largely diluted with mild trade effluents might yield an effluent which, although showing much lower figures for albuminoidTHE ANALYST.203 ammonia, might still be putrescible. The question was really one of percentage reduction and of available nitric nitrogen for helping to oxidise that portion of the albuminoid ammonia which was capable of being oxidised. Mr. BEVAN said that it had been his practice for many years to filter effluents, chiefly for the reason that, if there was any difference, the figures obtained for albuminoid ammonia or oxygen absorbed must necessarily be less after filtration than before. He should like to raise a mild protest against what he believed to be the fetish of the stored-up oxygen in the form of nitrates. I t was sometimes stated that it did not matter how high the albuminoid ammonia was, provided that plenty of nitrates were present; but to his mind the presence of a large quantity of albumi- noid ammonia was in itself quite sufficient to prove that an effluent was bad.If nitrates were present as well, it merely meant that purification had reached a certain point. That stored-up oxygen in nitrates was useful was no doubt theoretically correct, and practically some such action did to a certain extent go on; but experi- ments which he had made showed that many days were required for the absorption of the oxygen contained in the nitrates, and during those days the efflusnt remained a nuisance. Mr. MOOR asked whether the authors were entirely in agreement with these new methods of testing and with the abandonment of the idea which used to be held that a suitable percentage reduction in albuminoid ammonia and oxygen absorbed, together with a large formation of nitrates, would constitute a satisfactory standard.He should think that many effluents might pass the suggested new standards without being really satisfactorily purified. The PRESIDENT said that as yet he had had but little experience in carrying out the methods recommended by the Royal Commission. He had, however, like the authors of this paper, had considerable diEculty with the apparatus ‘( A ” and ‘‘ B ” in regard to the prevention of leakage. Theoretically, and in most cases practically, leakage could be prevented, but here the difliculty was a real one, as the total volume to be read off at the end of the operation was very small, and a comparatively slight variation, due to difference in temperature or to leakage, might vitiate the whole result.It was difficult to decide whether an effluent should be filtered and an allowance made for oxygen absorbed during filtration, or whether the effluent should be dealt with as it wa8, and at present the matter was probably one that was best left to the judgment of the analyst. It was all very well to recommend standards €or tidal waters, etc. ; the real difhulty se,emed to be in regard to individual effluents from chemical works and factories, for while some of these easily complied with the standards, others could not possibly do so. A great deal of difficulty, for instance, was caused by the residues from ammonia stills. In some cases these could be treated bacterially when largely diluted, but in many cases the quantity of free lime present was considerable, and this, becoming carbonated during treatment, formed a deposit on the filtering material, which soon rendered it inactive.He should like to hear whether the authors considered the iodine colorimetric method to be as accurate as titration. Dr. RIDEAL, in reply, said that the object of this paper was not so much to discuss the standards that should be adopted for judging the purity of effluents as204 THE ANALYST. to discuss the carrying out of the recommendations of the Royal Commission. Mr. Burgess and he had sent in a paper to be read at the forthcoming International Con- gress of Applied Chemistry, in which they criticised the two suggestions made by the Royal Commission-namely, as to the suspended matter, and as to the test of the rate of absorption of dissolved oxygen.As they had pointed out in the present paper, the Royal Commission, in their fifth Report, have prescribed the form of apparatus referred to, and it seemed as though this apparatus would have to be used, and the suspended matter would have to be filtered off before the test was made. They had therefore not now discussed the significance of the test in reference to the older ones of ‘( albuminoid ammonia ” or of “ the stoied-up nitrogen in nitrates,” but had merely endeavoured to find the most convenient way of carrying out the Royal Commission’s recommendations. He should like to mention here that, although this apparatus had been referred to in the ANALYST (Zoc.cit.), and was illustrated in the Report of the Royal Commission, it was not the apparatus which Dr. Adeney was a t present using. They had had the apparatus made according to the instructions contained in the Report, but had since ascertained that Dr. Adeney had improved the apparatus, and had abandoned the original form. They had found the later form to be much better than the original, and had been able to obtain fairly concor- dant readings with it after three or four days. I t was still, however, very difficult to shake for five days without breaking, and they did not think it would commend itself to analysts generally. The Commissioners’ instructions were to filter off the sus- pended matter before the analysis, and this, therefore, must be done whether analysts liked it or not.In the paper it was pointed out that oxygen was absorbed to some extent during the process of filtration, and therefore it was necessary to fully saturate the sample, and to determine the rate of absorption during the operation. It was their practice to have the sample saturated by the works’ manager in the way described in the paper, by mixing it with an equal volume of fully saturated water, and so introducing 2 parts per 100,000 of dissolved oxygen into the sample at the moment of collection-the temperature at the time being noted. There was, therefore, sufficient dissolved oxygen in the mixture to furnish the I+ parts tbat might be absorbed by the effluent during five days. I t would probably be twenty- four hours before the sample arrived at the laboratory, and the rate of absorption was then determined (assuming the sample to have been fully saturated at the moment of collection) after twenty-four hours, after two days, and after five days, as recommended by the Royal Cornmission.. The question of temperature, which Mr. Seyler had mentioned, was a very important one. They had made determinations at several different temperatures, and had found that, as was to be expected with this or any other method for determining the rate of absorption of dissolved oxygen, the results varied greatly. The figures they had obtained were given in their paper which was to be read at the International Congress, the point being that no definite temperature had been laid down by the Commissioners. Dr. Adeney had suggested that the test should be carried out at an optimum temperature (which would be about 1 8 O or 20” C.), so as to measure the maximum amount of putrefaction or absorption of oxygen ; but that would be obviously unfair, as in winter the absorp- tion would be much less. Personally, he thought the temperature should be theTHE ANALYST. 205 same as at the time of sampling, and twenty-four and forty-eight hours after the effluent was mixed with the river. With regard to Mr. Moor’s question, he did not think they agreed with the suggestions of the Xloyal Commission, he certainly was not in favour of removing the suspended matter. The suspended matter took up oxygen, and if it was important to measure the absorption of oxygen by the effluent, it seemed equally important in the case of the suspended matter. The Commissioners themselves pointed out that the suspended solids consisted chiefly of organic matter, were highly putrescible, and absorbed oxygen at an alarming rate. Mr. Burgess and he did not consider that, in presence of suspended matter, the colorimetric process was preferable to titration. Titration was better when there was much dark-coloured suspended matter, or when the liquid was very turbid; but in ordinary cases the turbidity could be corrected for as had been suggested. One advantage of the colorimetric process was that the nitrites could cause no disturbance through NO acting as a carrier of oxygen, as was the case in an ordinary Winkler titration.

ISSN:0003-2654    

DOI:10.1039/AN909340193b

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 205 A NOTE ON ENKABANG AND TEGLAM FATS AND KATIO OIL FROM SARAWAK. BY CECIL J. BROOKS, F.I.C. (Read at the Meeting, April 7, 1909.) Enkabang Fat is obtained from the fruit of a large jungle tree, Xhoreu Glzysbertinna, belonging to the order of Dipterocarps. Locally the seeds are known as Enkabang Jantong, but in the Singapore market as Sengkawang, which name includes the three varieties of exported Enkabang. The tree is of wide distribution in the country, growing freely in all lowland jungle, where it has no doubt been cultivated to a certain extent by the Dyaks, as the seeds find a ready market in Singapore, a considerable quantity being exported during a good fruit season. The fruit is a large, nearly oval nut, measuring about 19 inches in length, and having, when air- dried, an average weight of 13 grams.The shell is fairly tough, but easily removed. The market value is as much as $5 per picul (1334 pounds) in Kuching bazaar. The tree, however, is not a regular bearer; long intervals may a t times elapse between its fruiting periods. This, unfortunately, would form a serions drawback to its commercial cultivation. There was no special export until 1908, when 39,216 piculs left the country ; this points to the fruit season only occurring once in three or five years. The seeds are exported as the husked kernel, sun-dried, both Enkabang and Teglam mixed. There is a similar seed containing no oil which the Chinaman buys and mixes with these. AEuropean firm should purchase on the basis of The natives extract the fat by heat and pressure, and esteem it a valuable article The quantity of seeds exported in 1903 was 11,764 piculs.oil content.”206 THE ANALYST. of diet. The fat content is high, amounting to 31.2 per cent. on the nut and 46.7 per cent. on the kernel, when air-dried. A sample of fat of Dyak make had a slight odour, somewhat resembling tallow, and a slight but agreeable taste. The colour of the solid is yellow-grey, which on melting becomes golden-yellow. A section of the fat showed that the solidification had taken place in nodular masses, clearly defined by white lines. On examination the following figures were obtained : Specific gravity .. Melting-point ... ... ... ... 35" to 43" C. Solidifying-point could not be obtained, as Saponification value ... ...... ... 190.2 Acid value ... ... ... ... ... 24-7 Iodine absorption ... ... ... 30 per cent. ... the fat superfuses. Refractive index (Zeiss) 40" G.' ... . . , 45.0 (ND400 C. = 1.4559) A sample of the fat was prepared by extracting the seeds with carbon disulphide. After carefully removing the solvent from the fat, it had a slightly rancid odour, an unpleasant taste, and a yellow colour, which rapidly bleached to white on exposure to light ; when melted the colour was bright yellow. The following analytical data were obtained : Specific gravity ... ... ... ... loo "C. 0.856 15-5 Melting-point ... ... ... ... ... Saponification value ... ... ... ... Iodine absorption ... ... ... ... Free fatty acid ... ... ... ... ... Refractive index (Zeiss) 40" C. ... ... Unsaponifiable matter ... ...... Volatile fatty acids ... ... ... ... Insoluble fatty acids ... ... ... . . I 3 , , , mean combining equivalent 9 , , , melting-point ... ... 3 ) , , solidifying-point ... 9 , ,, iodine absorption Solidifying-point could not be obtained, as the fat superfuses. ... 33" to 37O c. 190.8 30 per cent. trace 46.1 (ND40" C. = 1.4567) 0.3 per cent. 1.4 7 9 95.8 ,, 282 55.5" c. 53" c. 31 per cent. Teglam Fat closely resembles Enkabang fat in its occurrence, etc. I t is obtained from the seeds of Isoptera Rorneensis, also a member of the order of Dipterocarps. The seeds are similar in shape, but smaller in size. They are known locally as Enkabang Changi. The fat for edible purposes is considered superior to any other, as it will keep in good condition for a number of years. A sample of the fat of Dyak preparation had a pale yellow-green colour, when fused was yellow, with a tinge of green ; the solidified fat, when exposed in section, exhibited a solid structure, with here and there white nuclei.It has a sweet buttery taste and slight odour.THE ANALYST.. 207 On examination the following analytical data were obtained : Specific gravity ... ... ... ... 100 O C. 0.856 15.5 Melting-point ... ... ... ... ... Saponification value . , . ... ... ... Iodine absorption ... ... Acid value ... ... ... ... ... Unsaponifiable matter ... ... ... Volatile fatty acids ... ... ... Insoluble fatty acids ... ... ... 9 9 9 9 mean combining equivalent 9 , ? I melting-point ... 9 9 9 9 solidifying-point ... I , 9 7 iodine absorption Solidifying-point could not be obtained, as the fat superfuses.Refractive index (Zei~sj.40~ 6' ... ... ... ... ... ... 28" to 31" C. 192.1 31.5 per cent. 11.3 0.5 per cent. 1-1 9 9 95.2 ,, 277 56" C. 51" C. 32-7 per cent. 45.2 (ND40" C. = 1.4561) Katio or Kaehiau Oil is obtained from the seeds of a species of Bassia, of the order Sapotacez. The tree grows in abundance in the swainps of the Sadong and Saribas districts. At present it has no commercial value, although highly prized by the natives for cooking and other food purposes. The small, oval, brown seeds, when air-dried, have an average weight of 0.391 gram, and contain 40 per cent. of oil. After the removal of the thin crisp shell the kernels gave 47.5 per cent. of oil. A sample of Dyak prepared oil had a bright yellow colour, a sweet taste, and a pleasant odour of almonds.The oil is non-drying. The following analytical data were obtained : Specific gravity at 15.5" C. ... ... ... 0.917 Solidifying-point ... ... ... ... ... 14" C. Saponification value ... ... ... ... 189.5 Refractive index (Zeiss) 40" C. ... ... ... 53.4 (ND40" C. = 1.4616) Iodine absorption ... ... ... ... ... 63.2 per cent. Unsaponifiable matter ... ... ... ... 0.41 ,, Acid value ... ... ... ... ... 1.8 Insoluble fatty acids ... ... ... ... 94.6 ,, 9 , I I mean combining equivalent 285 Volatile fatty acids"' ... ... ... ... 2.2 per cent. >? I ? 9 , ? ? 9 9 9 , melting-point ... ... 37.5O c. solidifying-point . . ... 36" C. iodine absorption ... 62.5 per cent. Elaidin Test.-The mass after one hour could not be displaced by shaking the bottle; after twelve hours the mass had the consistency of a soft American cheese. I n conclusion, I wish to tender my thanks to Mr. John Hewitt, of the Sarawak Museum, for kindly providing me with samples and botanical notes; and to Mr. E. R. Bolton, for determining the refractive indices recorded in this paper. DISCUSSION. Mr. L. MYDDELTON NASH (by whom the paper was communicated), in reply to a question put by the President, said that, so far as he knew, these fats had not yet208 THE ANALYST. been exported to this country, but he understood that some interest was being taken in them from the point ol view of their use for edible purposes, and it was possible that they might shortly be introduced. Unfortunately, however, a8 Mr. Brooks had remarked in the paper, the tree did not bear fruit every year, but only s t intervals of from three to five years, so that the supply probably would not be regular.

ISSN:0003-2654    

DOI:10.1039/AN9093400205

出版商:RSC    

年代:1909

数据来源: RSC

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208 THE ANALYST. THE COMPOSITION OF MILK. BY H. DROOP RICHMOND, F.I.C. (Read at the Meeting, April 7, 1909.) Composition of illilk during 1908.-Of the 39,469 samples analysed in the laboratory of the Aylesbury Dairy Company during 1908, 34,461 were samples of milk. The average composition of 17,433 samples received from the farms is given in the table below. COMPOSITION OF MILK DURING 1908. Morning Milk. Evening Milk. Mean. SpeciGc Gravity. Specific Gravity. Specific Gravity, Solids- not- Fat. 8 '95 8.91 8.92 8.89 8 -89 8 -88 8.76 8 *75 8.85 8 *92 8.99 9.01 Solids- not- Fat. 8.97 8-92 8.92 8-86 8 -87 8.81 8-67 8-70 8.83 8'93 9 '00 8 '99 Solids- not- Fat. 8.96 8.91 8 -92 8-88 8-88 8.85 8.72 8-73 8.84 8.93 9.00 9.00 Total Solids. 12-61 12-46 12'47 12.39 12.30 12-17 12.16 12-25 1250 12-58 12-69 12.76 Total Solids.12.79 12-62 12.64 18.63 12.51 12-37 1232 12-49 12-74 12.88 12.90 12.90 Total Solids. 12.96 12-79 7 2.80 12.67 12.73 12.57 12.48 12.73 12-97 13.08 13-19 13.04 Fat. 3-66 3-55 3.55 3.50 3.41 3.29 3 a 4 0 3-50 3.65 3.66 3-70 3 '75 Fat. 3 *99 3-87 3'88 3-82 3.86 3.76 3.81 4*0:3 4.14 4.15 4.10 4'05 Fat. 3.83 3-71 3 *72 3.65 3-63 3-52 3 -60 3.76 3.90 3-90 3.90 3.90 Month. January ... February ... March ... April ... May ... June ... August . . . September ... October ... November.. . December ... July ... 1 -0323 1 -0322 1.0322 1.0329 1 *0323 1.0324 1.0318 1'0317 1'0319 1 m 2 2 1.0325 1.0325 1,0321 1 *0320 1.0320 1'0318 1'0318 1.0317 1-031 1 1*0310 1.0314 1.0319 1 '0322 1 '0323 1,0322 1.0321 1 -0321 1 *0320 1 *0320 1 '0320 1.0314 1.0313 1.0317 1'0321 1 '0323 1.0324 Average.., 1.0322 1244 3.55 8 9 9 1 *0318 12.83 3-95 5-88 1 *0330 12-63 3.75 8 -88 There is the usual difference between the morning and evening milk of 0 4 per cent., and the lowest fat occurs in June and the highest in the last four months of the ye&r. It is a little unusual that the Baine average percentage of fat should have occurred in four successive months, as it has been generally found that October and November are the months in which the fat is highest, while September and December are not quite so good. As an indication of the influence of the temperature of the air on the quality of milk, it may be mentioned that October and November were mild, while a cold spell occurred in December ; mild weather has a, tendency to occasion a flush of milk comparatively poor in fat, whilst cold weather acts in a contrary direction.THE ANALYST.209 The average percentage of fat found during 1908 is the same (3.75) as that found in 1907, and agrees with the average of the past ten years. In continuation of the tables published during the past three years, the incidence of samples containing less than 3.0 per cent. of fat on the morning milk during May and June is given. Percentage of Samples containing , 1 2.7 to 2'8 Below 2-7 2.9 t o 3.0 2.8 to 2.9 per Cent. Fat. per Cent. Fat. per Cent. Fat. per Cent. Fat. May, 1908 ... 0.6 per cent. 0.5 per cent. 0.2 per cent. nil June, 1908 ... 2.3 ,, 0.4 7 , 0.2 ,, nil The number of these samples is less than in former years. Some Uses of the Determiizntion of the Aldehyde Fagure.--I trust that I may be permitted to again refer to the aldehyde figure, but the great use that this determina- tion has been is my excuse. During the past year I have had to control the preparation of a number of milk mixtures made up for infant feeding from prescriptions, and in some of these it has been necessary to estimate rapidly fat, proteins, milk-sugar, and cane-sugar.The problem was sifnplified by all the materials used being available for asalysis, and it was found that by determining fat (by the Gerber method), specific gravity, and aldehyde figure, in the samples and in the milk from which the samples were made, the four determinations required could be obtained with sufficient accuracy for control purposes, By estimating the ratio of solids-not-fat to aldehyde figure in the milk used, and multiplying the aldehyde figure of the mixture by this ratio, the amount of solids- not-fat derived from the milk is obtained, and the difference between the actual amount and this gives the added sugar.Test mixtures were made up containing 3-15 per cent., 2.30 per cent., and 2-23 per cent. of cane-sugar, while 2.90 per cent., 2.44 per cent., and 2.13 per cent. of cane-sugar was found in these. The method does not, of course, distinguish between added cane-sugar or added milk-sugar, but when it is known what the added substance is, an estimation of sufficient accuracy is obtained. The aldehyde figure is also of use in the estimation of salt in milk or butter- milk. It sometimes happens that when churning both salt and water find their way into the butter-milk; when the butter-milk is to be sold, it is important to be able to rapidly estimate both the proportion of water and of salt.I t was found that chlorides could be titrated in milk with & silver nitrate solution, using potassium chromate as indicator, and that 10 C.C. of milk took on an average 3-45 C.C. silver solution, with extremes of 3.35 C.C. and 3.6 C.C. in nine samples. silver solution for 10 C.C. of milk could be deduced with considerable accuracy by multiplying the alde- hyde figure (obtained with TG strontia) by 0.171, and subtracting this quantity from the quantity actually used; the remainder was a measure of the sodium chloride. A series of determinations showed that 1 gram of sodium chloride added to It was further found that the number of C.C.of210 THE ANALYST. 100 C.C. of milk raised the density by 0,00735, and by multiplying the amount of salt found by this figure the increment of density due to the addition is deduced, and subtracting this from the density found, the density of the milk is obtained. From this last figure and the fat the solids-not-fat can be calculated, and from this the amount of added water roughly deduced. The following figures will show the accuracy of the method : 1 2 3 4 5 Salt added ... 0.49 0485 0.7 1 0-32 0.62 Salt found ... 0.47 0.490 0.71 0.31 0.62 Water added ... 10 - 10 20 35 Water found ... 10 - 9 19 34 Adulteration of Cream with Condensed MilTc.-It is now a, fairly common A practice, especially in the North of England, to mix condensed milk with cream.sample which came into my hands contained : Per Cent. Total solids ... ... ... ... ... ... 37.89 Fat ... ... ... ... ... ... ... 27-42 Ash ... ... ... ... ... ... ... 1.23 Solids-not-fat ... ... ... ... ... ... 10.47 A genuine cream containing this percentage of fat would contain 6.5 per cent. of solids-not-fat. DISCUSSION. Mr. JOHN GOLDING said that, although Mr. Richmond’s figures were most acceptable, and were looked for with interest by people all over the country, they did a certain amount of injustice to some farmers in the Midlands who had to milk their cows at very uneven intervals. He should like to ask if Mr. Richmond had experienced any difficulty with regard to sampling. With milk that had stood over night, even after a railway journey, he (Mr.Golding) had found it almost impossible to get the fat thoroughly distributed without using a perforated disc or pouring the milk from one churn to another. In two recent cases which he had had to investigate it was clear that the vendors had suffered injustice through uneven distribution of the cream throughout the vessel sampled. Mr. L. MYDDELTON NASH said that, while according to Mr. Richmond’s figures the proportion of non-fatty solids did not seem to vary appreciably from month to month, he understood that the yield of casein from separated milk varied considerably at different seasons of the year-he believed from 3 to 3.8 per cent. If that were so it would seem that the lactose and salts should vary inversely with the percentage of proteins, and he should like to hear if Mr.Hichmond had any information on this point. Mr. MOOR desired to ask whether the average of 3.75 per cent. of fat had been obtained by taking the average of the whole number of samples that Mr. RichmondTHE ANALYST. 211 dealt with, because he (Mr. Moor) had heard it stated that in making up these averages Mr. Richmond took out the figures of the milks which fell below the Government standard, or below some other standard, thereby intentionally obtaining a false set of figures. The PRESIDENT remarked that, as he had mentioned a little time ago, some difficulty had been created in Scotland by the returning as abnormal ” of a very large proportion of milk samples in which the non-fatty solids were below 8.5 per cent., and he thought it would be interesting if Mr.Richmond would state what percentage of his samples might be classed as abnormal in this respect. Mr. RICHMOND said that the number of samples in which the non-fatty solids fell below 8.5 per cent. was very small indeed, and only two samples (one of which was from a single cow) contained less than 8.3 per cent. Most of the cases in which there was a low percentage of non-fatty solids occurred within the months of July, August, and September. With regard to sampling, each churn was stirred with a stirrer before the sample was taken. He had not the figures for casein, but the total proteins, as shown by the aldehyde figure, varied a little according to the season of the year, being higher in the winter and lower in the spring, summer, and autumn.I n reply to Mr. Moor’s question, the average he had given was practically an average of the total samples. The only samples rejected were those in the case of which there was distinct evidence that the milk had been tampered with. The number rejected in the course of the past year was twenty-one, the total number being 17,000 odd. This, of course, was a very small proportion, and even if the rejected samples had contained no fat at all, it would scarcely affect the average percentage of fat in the second decimal place. For a sample to be rejected for lowness in fat he required some such evidence as the arrival of the milk in a churn of which the seal had been broken and in which the quantity of milk did not cor- respond with the quantity stated on the label--i.e., there must be absolutely definite evidence that something had been removed from the churn. In the absence of such evidence the sample was included in the average. I t was therefore absolutely untrue to say that the averages he gave were manipulated in any way so as to cause them to be higher than they actually were. He understood from Mr. Moor that the statement referred to was made in court, and he should like to warn the gentleman who made it that he laid himself open to an action at law. He (Mr. Richmond) very much resented any imputation of that kind, and he was grateful to Mr. Moor for raising the question and giving him an opportunity of denying it.

ISSN:0003-2654    

DOI:10.1039/AN9093400208

出版商:RSC    

年代:1909

数据来源: RSC

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212 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Estimation of Acetanilide in Hydrogen Peroxide Solutions. E. Waller. (Chem. Zeit., 1909, 33, 320.)-From 6 to 7 grams of potassium or sodium hydroxide are dissolved in about 20 C.C. of water in a double-necked flask of 200 C.C. capacity. From 25 to 30 grams of granulated zinc and a measured quantity (not exceeding 50 c.c.) of the solution under examination are then introduced, and one neck of the flask connected with a source of steam, whilst the other is attached to a condenser, the outlet of which is connected with a Peligot’s absorption-tube, or similar device containing moderately strong hydrochloric acid. The tube introducing the steam is made to pass nearly to the bottom of the liquid.The flask is gradually heated, and when about half its contents has distilled a current of steam is passed through it. When the odour of aniline can no longer be recognised in the vapour the absorption- tube is disconnected, and any aniline still present collected in another vessel and titrated separately. The solution for the titration is prepared by adding an excess of bromine to a cold solution of 25 grams of potassium hydroxide in 20 to 40 C.C. of water, diluting the liquid to 200 c.c., expelling the excess of bromine by boiling, and making up the solution to a litre. This solution, 1 C.C. of which is approximately equivalent to 0.01 gram of acetanilide, is standardised upon a solution of 0.5 gram of acetanilide in 200 C.C. of water. C. A. M. Estimation of Butter-Fat in Margarine in the Presence of Cocoanut Oil.1. Monhaupt. (Chem. Zeit., 1909, 33, 305-306.)-By modifying both the Reichert-Meissl process and the process described by Kirschner (ANALYST, 1905, 30, 205), it is shown that small quantities of butter-fat may be detected in the presence of much cocoanut oil. The value of the results obtained is shown in the tables given below, the method of working being as follows : Five grams of-the sample are saponified as usual with sodium hydroxide in glycerol solution, and the soap is dissolved in 90 C.C. of water; 50 C.C. of dilute sulphuric acid are added, and the mixture is heated for some time until the liberated fatty acids form a clear layer. After cooling, the aqueous portion is passed through a dry filter, and the clear filtrate is distilled, a little pumice-stone being added to the flask, until 110 C.C.of distillate have been collected. This distillate is filtered, and 100 C.C. of the filtrate are titrated with The number of C.C. of the alkali required multi- plied by 1.1 gives the “new ” Reichert-Meissl value of the fat. The neutralised distillate is then treated with silver sulphate, etc., as described by Kirschner (Zoc. cit.). The result obtained is termed the ‘‘ new ” Kirschner value. The influence of from alkali solution as usual.THE ANALYST. 213 Percentage of Cocoanut Percentage of Butter- New Reichert-Meissl Oil. Fat. Value. New Kirschner Value. 15 Percentage of Cocoanut Oil. 0 1 2 Percentage of Butter-Fat. New Kirschner Value. 0.50 0.72 0.99 0.24 0.39 0.62 25 0 1 2 0.88 0.99 1-21 0.30 0.55 0.69 35 0 1 2 1-10 1-32 1.50 0.36 0.63 0.81 The difference produced in the Kirschner value by small amounts of butter-fat is still more plainly marked if 20 grams of the sample be taken for the estimation, and the process carried out as described above as regards the first distillation. Correspondingly larger quantities of water and sulphuric acid are employed and 440 C.C.of distillate are collected. The distillate is then rendered slightly alkaline, evaporated to a volume of 110 c.c., exactly neutralised, and treated with silver sulphate. One hundred C.C. of the filtrate from the silver precipitate are distilled after the addition of 20 C.C. of dilute sulphuric acid, and 30 C.C. of water, and 110 C.C. of distillate are collected.alkali required to neutralise 100 C.C. of the filtered distillate, when multiplied by 1.21, gives the ‘( new ” Kirschner value for 20 grams of the fat. Operating in this way, the following results were obtained : The number of C.O. of 25 0 1 1.30 2.05 35 0 1 1.63 2-40 w. P. s. Water in Butter. A. J. J. Vandevelde and A. Stewart. (BzdZ. SOC. Chim. Belg., 1909, 23, 95-98.)-Results of analyses are given which show that water evaporates rapidly from butter when the latter is wrapped in parchment paper and the package kept in a closed cardboard box. After a few months, even the centre of the pat of butter contains much less water than it did originally. Samples of butter can214 THE ANALYST. be kept in closed glass bottles without change in their water-content, although there may be some little difficulty in remixing the separated water with the bulk of the sample in order to obtain an average sample for analysis.w. P. s. Estimation of Caffeine in Coffee. K. Lendrich and E. Nottbohm. (Zeit. Cnterszich. Nahr. GenzLssm., 1909, 17, 241-265.)-The method proposed is given below in detail ; it is the result of a considerable amount of research work, each operation involved in the process-namely, the preparation of the sample, the extraction, the treatment with permanganate, the separation of the oil, etc., and the final extraction of the caffeine-having been submitted to an exhaustive examination in order to ascertain the procedure giving the most trustworthy result. Twenty grams of the raw or roasted coffee, ground so as to pass through a sieve of 1 mm.mesh, are moistened with 10 C.C. of water, and the mass is stirred from time to time for a period of two hours. The moist powder is then transferred to an extraction thimble and extracted with carbon tetrachloride for three hours (cf. ANALYST, 1909, 50). To the extract thus obtained is added 1 gram of solid paraffin, the carbon tetra- chloride is evaporated, and the residue is extracted with four successive quantities of boiling water, using 50 C.C. of the first extraction, and then three quantities of 25 C.C. each. The united aqueous extracts are cooled, passed through a moistened filter, and the latter is washed with hot water. In order to remove colouring matters and other substances which are extracted together with the caffeine, the filtrate is next treated at the ordinary temperature with from 10 to 30 c.c.-that is, a slight excess- of 1 per cent.potassium permanganate solution. At the end of fifteen minutes the excess of permanganate is decomposed by the addition, drop by drop, of 3 per cent. hydrogen peroxide solution containing 1 per cent. of acetic acid. The whole is then heated for fifteen minutes on a boiling water-bath and filtered, the residue, consisting mainly of manganese dioxide, being washed with boiling water. The filtrate and washings are evaporated to dryness, the residue is dried in the steam-oven for fifteen minutes, and at once extracted with warm chloroform. The chloroform solution is then evaporated, and the residue of caffeine obtained is weighed, after being dried at a temperature of 100" C.for thirty minutes. Instead of evaporating the filtrate obtained after the permanganate treatment, it may, if preferred, be extracted directly with chloroform, and in cases where the greatest accuracy is desired the nitrogen may be estimated in the residue of caffeine, and the alkaloid then calculated from the quantity of nitrogen found. I t is shown, however, that the residue of caffeine obtained in the above process is practically pure. With slight alterations the process may be applied to the estimation of caffeine in coffee extracts (essences) and in drugs con- taining caffeine ; it is also applicable to the estimation of theobromine in drugs. w. P. s. A New Method of Analysing Calcium Citrate and Lemon-Juice.L. and J. Gadais. (Bull. SOC. Chim., 1909, [iv.] 5, 287-289.)-Twenty grams of calcium citrate are boiled for a few moments yith 30 C.C. of water and 25 C.C. of hydrochloric acid (22" Be.), and the liquid then cooled, made up to 250 c.c., and filtered. Twenty- five C.C. of the filtrate are exactly neutralised with :-potassium hydroxide solutionTHE ANALYST. 215 (with phenolphthalein as indicator), then treated with 1 C.C. of a saturated solution of calcium chloride, evaporated to about 25 c.c., and filtered while very hot. The precipitate of calcium citrate is washed seven or eight times with as little boiling water as possible and dried at 105" C. The filtrate is concentrated to 15 C.C. and filtered from the fresh precipitate of calcium citrate, which in turn is washed four or five times with as little boiling water as possible and dried at 105" C.If required, the washings are concentrated to 15 c.c., and any precipitate treated as before. Finally, an equal volume of 95 per cent. alcohol is added to the filtrate and washings, and, should there be any precipitate, this is collected and dried with the three pre- ceding precipitates. When dry these precipitates are ignited, apart from the filter- paper, the resulting calcium carbonate treated with 30 C.C. of :-hydrochloric acid, and the excess of acid titrated with ;-potassium hydroxide solution. The number of C.C. of acid required to neutralise the calcium carbonate, multiplied by the factor 0.07, gives the amount of citric acid in the sample. In the case of citrates containing much sulphate it is advisable to do the ignition over a spirit-lamp, and to treat the calcium carbonate with 10 C.C.of hydrogen peroxide before adding the hydrochloric acid. In analysing lemon-juice 120 C.C. are diluted to a litre, 25 C.C. of this liquid neutralised with :-potassium hydroxide solution (free from iron and carbonate), then treated with 20 C.C. of a saturated solution of calcium chloride, and the calcium citrate separated as described above. C. A. M. Detection of Caramel in Wine, Cognac, and Beer. A. Jagersehmid. (Zeit. Untersuch. Nuhr. Genussm., 1909, 17, 269.)-The following process is recom- mended : 100 C.C. of the wine, cognac, or beer are mixed with a quantity of albumin solution (prepared by mixing equal quantities of fresh white of egg and water), and the mixture is heated, with constant stirring, until the albumin has coagulated com- pletely.After filtration, the filtrate is evaporated to a syrup, which is then divided into two parts : one portion is emulsified in a porcelain basin with ether, and the other portion with acetone. When separation has taken place the ethereal solution is decanted into a basin, the solvent is allowed to evaporate, and the residue is treated with 2 drops of a freshly prepared solution containing 1 gram of resorcinol in 100 C.C. of concentrated hydrochloric acid. A cherry-red coloration is produced at once, should caramel be present. The acetone solution is filtered, if necessary, and mixed with an equal volume of concentrated hydrochloric acid; the presence of caramel ie denoted by the appearance of a bright red coloration.w. P. s. The Detection of Colophony in Tolu Balsam. Perrot and Goris. (Bull. Sciences Pharmacol., November, 1908 ; Ann. de Chim. A m . Appl., 1909, 14, 106.)- Colophony is occasionally added to Tolu balsam to give firmness and transparency. To detect the addition, 5 grams of the powdered sample are treated with 30 C.C. of carbon bisulphide, to render the balsam viscous. The carbon bisulphide is then evaporated, and the residue taken up with 10 C.C. of petroleum spirit. The filtered solution is treated with a solution of copper acetate (1 : 1,000), and the formation of a green coloration, due to copper abietate, indicates the presence of colophony. The test will detect as little as 2 per cent. of rosin in Tolu balsam, the least quantity that216 THE ANALYST.it will pay to add. samples give a green coloration similar to that of copper abietate. The test is not applicable to Peru balsam, since certain pure C. A. M. Chemically Treated Flours. E. F. Ladd, H. P. Bassett, and H. L. White. (Bull. Gov. Agric. Exp. Sta. Ag~ic. Coll., N.D., December, 1908; Chem. News, 1909, 99, 110-112, 127-129, 133-136.)-This paper consists of two parts : (1) The Bleaching of Flour, and (2) The Effect of Bleached Flour Extracts on Rabbits. 1. The Bleaching of Flour.-The authors state that the only paper yet published dealing with the poisonous effects of nitrogen peroxide and the substances produced by its action on digestion is one by J. H. Shepard, Chemist of the South Dakota Experimental Station and Food Commission (crf.also Ladd, Stallings, and Allway, Bull. 102, Nebraska Experimental Station). Nitrous acid fumes or nitrogen peroxide produced in various ways are used for bleaching and “ageing” flours, which, after treatment, can be shown to contain nitrogen both as nitrite and nitrate. The flour for one loaf (373 grams) may show as much as 2.416 mgms. NaNO,. This is equivalent to 13.14 parts of nitrogen as nitrite nitrogen per million. Another sample of bleached flour showed in 373 grams only half this amount. The finished bread retains from one-third to one-half of the original nitrites in the flour. Thus 373 grams flour produced a loaf weighing 18 ounces, or 509 grams, and contained 0.443 mgm. as NaNO,. Another sample of bread made from overbleached flour retained 3.546 mgms.NaNO,, equivalent to one-third of that present in the flour. Fat extracted from unbleached flour, even when the latter has been aged for nine months, contains no nitrogen, but that from bleached flour gives a strong nitrogen reaction (confirming Lewkowitsch). The iodine absorption figure (Hanus modification) for the fat of unbleached flour is 101 or over, while this number may fall to 84 in the case of bleached flour, and is low in proportion to the amount of bleaching. This variation in the iodine value and nitrogen content of bleached flour fat shows that the nitrous acid fumes affect the fat of flours exposed to their influence. That artificial bleaching has not the same effect as natural maturation is shown by the fact that no reduction occurs in the iodine value of the fat from naturally aged flours.Gluten isolated from an unbleached flour was artificially digested with pepsin solution in five hours, as against nearly nine hours when the gluten was obtained from bleached flour. Similar differences, but less strongly marked, were noticeable when gluten, isolated and then baked, or bread itself, was subjected to pepsin hydrolysis, the total time required being much reduced. In the case of pancreatic digestion, unbleached flour gluten (unbaked) took two houp, as against three for that from bleached flour; and the time of digestion of the baked gluten and of bread was in favour of the unbleached flour. I t was observed that bread made from unbleached flour went mouldy in three or four days, but when made of bleached flour not until after ten days.Experiments made by inoculating bread with this mould showed that the bleached flour behaved as if it contained an antiseptic. In order to determine what constituent of the flour was acted on by the nitric oxide,THE ANALYST. 217 experiments were made which showed that the gluten or protein was affected, possibly with the formation of a diazo-like body. 2. The E$ect of Bleached Flour Extract on Rabbits.-Alcoholic extracts of unbleached, commercially bleached, and overbleached flours were given to rabbits, along with controls made of physiological salt solution and alcohol. Unbleached flour extracts were without effect ; commercially bleached flour extracts were fatal in a few hours, while extracts from overbleached flours were immediately fatal, whether water or alcohol was used for extraction.When alcoholic or aqueous extracts of overbleached flours were neutralised with sodium bicarbonate they still proved fatal to the rabbits in a short time. All nitrite reacting materials disappeared in the preparation of the aqueous extracts, indicating the presence of toxic material other than nitrites. Post-mortems were made on all the rabbits that died, and full details are furnished. the fact seems to have been clearly established that commercially bleached flour such as we found on the market, and purchased for use in this experiment, did contain toxic bodies in sufficient quantity to cause death in animals to which the same was fed as an extract.” The Secretary of Agriculture (Washington, D.C.) has recently issued a decision that flour bleached with nitrogen peroxide is an adulterated product under the Food and Drugs Act.The authors state that H. F. E. H. Estimation of Formic Acid in Fruit Juiees. F. Schwarz and 0. Weber. (Zeit. Untersuch. Nahy. Genussm., 1909, 17, 194-197.)-As preparations containing formic acid as their active ingredient are now sold and used as preservatives of fruit- juices, the following method is described for the estimation of this acid. I t depends on the estimation of the volatile acids before and after oxidation with chromic acid, the difference or loss in acidity being due to formic acid, which is destroyed by the .oxidising agent. From 25 to 50 grams of the sample of fruit-juice are steam-distilled, 400 C.C.of distillate being collected ; if superheated steam be employed, it is sufficient to collect 250 C.C. of distillate. sodium hydroxide solution, using phenolphthalein as indicator, and evaporated to dryness. This evaporation is necessary in order to remove small amounts of alcohol (present ,naturally in most fruit-juices, and also introduced with the indicator), which in the -subsequent oxidation would yield acetic acid. The dry residue is dissolved in about .20 C.C. of water, 30 C.C. of a solution containing 12 grams of potassium bichromate and 30 C.C. of concentrated sulphuric acid in 100 C.C. of water are added, the mixture is boiled under a reflux condenser for ten minutes, and again submitted to steam distillation. The same volume of distillate is collected as in the first distillation- namely, 400 or 250 c.c.-and is titrated as before.The difference in the two titrations The distillate is exactly neutralised with represents the quantity of formic acid present. w. P. s. Reversed Filtration and the Determination of Fibre in Foods, etc. W. Iwanowsky. (J. R z ~ s s . Phys. Chem. Soc., 1908, 40, 1753-1756; J. Chem. SOC., 1909, 96, 272.)-The apparatus consists of a tube widened at one end, into which fit two perforated discs of glass or porcelain, holding between them the filtering medium, and retained in position by means of a rubber band. The tube i s218 THE ANALYST, immersed in the solution to be filtered, and connected with an exhaust flask. For the estimation of fibre, the material is boiled with dilute sulphuric acid, the solution then drawn through the filter fitted with a cloth disc (the best material is I ‘ dickes Creme-Tuch”), and the residue washed twice with water, this being sucked through in each case.The cloth filter and residue are then boiled together with dilute caustic alkali, which completely dissolves the cloth. Four discs of quick-filtering paper being ready dried and weighed, the alkaline liquid at 30” to 40” C. is drawn off through the filter fitted with a ‘‘ quick” paper. The residue is boiled with water, which is sucked through another of these papers. Finally, the residue and the two used papers are boiled with water, and the whole filtered through the two remaining filter-papers, which are then washed, dried, and weighed.The results are accurate. A. R. T. The Composition of Brewers’ and Distillers’ Grains. T. W. Fagan and C. Allan. (Edinburgh and East of Scothad Coll. Agriculture, 1909, Bull. 16, 1-21.) -Twenty-three samples of grains from four breweries and seventeen samples from three distilleries were analysed before souring had taken place. The water in the brewers’ grains ranged from 73.07 to 78 per cent., with an average of 75.83 per cent. ; whilst the distillers’ grains contained from 72.89 to 79.89 per cent., with an average of 76.08 per cent. The dry matter in both kinds of grains had the following average percentage composition : Digestible Fibre. Ash’ Carbohydrates. oil, Nitrogenous Matter. Brewers’ grains . . . ... 4.99 20.61 21.03 4-50 48-85 Distillers’ grains . .. ... 5.96 18.75 17.76 3.23 54.37 Th6 nitrogenous substances were fairly constant in amount in the grains from the same brewery, but showed considerable variations (18.26 to 22.07 per cent.) in the grains from different breweries. Distillers’ grains are liable to vary to a still greater extent in this respect, as well as in the amount of oil. C . A. M. Deteetion of Added Proteins in Meat Preparations. E. Feder. (Zeit. Untersuch. Nahr. G C ~ Z U S S ~ , 1909, 17, 191-194.)-A compound used as a ‘‘ binding ” material for sausages was found by the author to consist of about 70 per cent. of protein, probably casein; it contained 8 per cent. of mineral matter, including 1-95 per cent. of calcium oxide, 0.12 per cent. of magnesium oxide, and 3 per cent.of phosphoric anhydride. I t is therefore possible, by estimating the calcium oxide, to detect the presence of such a material in sausage-meat, meat-pastes, etc., as ordinary flesh contains far less calcium oxide than does casein. The alkalinity of the ash also affords evidence of the addition, as proteins of the nature of casein are generally rendered soluble by treatment with sodium hydroxide. The following percentages of calcium oxide were found to be present in various meats, the results being calculated on the dry, fat-free substance : Beef, 0.060 ; pork, 0.066 ; pigs’ skin, 0.114 ; pigs’ feet, 0.134 ; veal, 0.086 ; calves’ feet, 0.058; calves’ sinew and cartilage, 0.226. The ash from 100 grams of the above-mentioned casein preparation required 260.2 C.C. of & acid for neutralisation, whilst the ash from 100 grams of dry, fat-free pork required only 8.1 C.C. of TG acid.w. P. s.THE ANALYST. 2 19 The Solubility of Kauri Coprzl. C. Coffignier. (Bull. Soc. Chim., 1909, [iv.], 5, 289-296.)-Four kinds of kauri copal from New Zealand were used in the author's experiments : white and brown kauri, bus& kauri, and picked busch kauri. Of the two last, bzisclz copal is collected from the foot of the tree, whilst the other is taken from the tree itself. The following amounts of insoluble matter were left on boiling these resins with the solvents : Ethyl alcohol . . . ... Methyl alcohol ... ... Amyl alcohol .... ... Ether . . . ... ... Chloroform ~. . ... Benzene ... ... ... Acetone ... ... ... Turpentine oil . '.... Benzaldehyde , . . ..* Amyl acetate . . . ... Aniline ... ... ... Carbon tetrachloride . . . White Kauri. Per Cent. 6.60 49-60 Soluble 61.80 54.40 66.70 8.90 77.50 Soluble 9 , si.io Brown Kauri, Per Cent. 35.80 61.90 Soluble 60.70 58.70 70-60 38-70 73.60 Soluble , I 2 77.30 Busch Kauri. Per Cent. 12.30 47-30 Soluble 55.10 50.70 61.70 20.70 72-90 Soluble 7i.bO 9 9 Picked Busch Kauri. Per Cent. 4.20 34.20 Soluble 51.10 43.40 57.60 11.30 63 Soluble 9 9 6 i ' These results confirm the generally accepted opinion that brown. copal is harder than white copal. C. A. M. Estimation of Nicotine as Nicotine Silicotungstate. G. Bertrand and M. Javillier. (Bzill. Soc. Chim., 1909, [iv.], 5, 241-248.)-0n adding a 5 per cent. solution of potassium silicotungstate to a solution containing 1 part of nicotine per million and about 8 per cent.of hydrochloric acid, a crystalline precipitate is formed after the mixture has stood for a day or so. If the solution contains 1 part of nicotine in 300,000, and 0.1 per cent. of hydrochloric acid, an immediate turbidity is obtained on adding the reagent. The crystals and the precipitate consist of nicotine silico- tungstate, which, when dried at a temperature of 30" C,, has the composition : 12WO,.Si0,.2H,0.2C,,H,,N2 + 5H,O. I t loses 5 molecule8 of water when heated for one hour at 120" C. For the estimation of nicotine in tobacco, 12 grams of the sample are boiled under a reflux condenser with 300 C.C. of 0.5 per cent. hydrochloric acid ; the mixture is then cooled, filtered, and 250 C.C. of the filtrate are treated with a 10 to 20 per cent. solution of potassium silicotungstate.If the quantity of alkaloid present be small, the mixture is set aside for twenty-four hours, or longer. The precipitate is collected on a filter, washed with water containing a little hydrochloric acid and a few drops of the reagent, and is then transferred to a flask, mixed with calcined magnesia, and submitted to steam distillation. The nicotine in the distillate is then estimated by titration with sulphuric acid. w. P. s.220 THE ANALYST. Estimation of Quinine in Cinchona Bark. W. Duncan. (Pharm. J., 1909, 82, 429-430.)-While quinine sulphate is for the most part precipitated from its solutions in water at a low temperature by means of a large addition of sodium sulphate, the other alkaloids of cinchona are practically unaffected by such treatment.On this fact the author bases a method for the estimation of this alkaloid in cinchona bark. The mixed alkaloids from 10 grams of bark, separated by any of the usual methods, are dissolved in the minimum of sulphuric acid, the solution diluted to 100 C.C. with water, heated on the water-bath, and rendered neutral to litmus by means of decinormal alkali. To the neutral solution 10 grams of sodium sulphate are added, and when dissolved the liquid is set aside for twenty-four hours. The crystals are collected, washed with water saturated with quinine sulphate, and dried. If dilution be too great, the quinine is not all Precipitated; but if the liquid be too concentrated, there is a danger of other alkaloids being precipitated.A low temperature gives the best results. Any excess of alkali added when the hot liquid is being neutralised causes a separation of alkaloidal hydrate, which is best re- dissolved by addition of alcohol, when neutralisation by means of the requisite quantity of acid may be completed and the alcohol boiled off. The washed quinine sulphate crystals are titrated with gG alcoholic alkali and phenolphthalein. A. R. T. Scammony Resin, F. 0. Taylor. (Amer. J. Pharnz., 1909, 81, 105-111.) -The author gives the following results of the analysis of several samples of pure scammony resin.(prepared by him from the crude drug, Convolvulus scammonia), and of samples of so-called ‘( Mexican scammony,” prepared from the root of Iponzaa Onkabensis, together with samples believed to be from mixtures of these two drugs : No.Resin. True Scammony (?) Mainly (‘ Mexican Scammony ” . . . ‘‘ Mexican Scam- True Scammony . . . mony ” ... ... 9 ) 9 9 9 , 9 9 $ 9 ,, ... ... ... True Scammony (?) ‘‘ Mexican Scam- mony” ... ... field of Resin from Root. Per Cent. 8.1 12.2 16.75 7.93 8.06 7.71 8.52 - 16.83 Mois- ture. Per Cent. 2.18 1.94 1.77 1.71 1.74 1-86 1-65 2-09 2.03 Ash. Per Cent. 0.12 0.08 0.09 0.05 0.09 0.09 0.20 0.15 0.29 Ether- Soluble Matter. Per Cent. 99.0 99.5 99.6 99.7 99.3 99.3 99.0 98.8 96.5 Acid Value. 21.1 14.6 15.5 15.6 18.2 18.8 21.3 14.5 21.5 Saponi- fication Value. 232.4 198.4 186.6 238.1 238.0 240.5 239.4 232.8 187.1 =Ester Value. 211.3 183.8 171.1 222.5 219.8 221-7 218.1 318.3 165.6 Iodine Value.13-3 8.7 8.7 10.8 13.0 14.3 14-6 10-5 11.5 From the above results it is seen that the saponification values of these two resins are so different that their determination affords a valuable means ofTHE ANALYST. 221 differentiating between them. while that of to contain small amounts of the resin of Mexican scammony. double the yield of resin of the true drug. True scammony resin gives a value of about 238, Samples 1 and 8 appear The false root gives Mexican scammony ” is a little below 190. A. R. T. Estimation of Sodium Benzoate in Catsups, Sauces, etc. J. Hortuet. (State of Minnesota Dairy and Food Dept., Report, 1909, 24 - 25.) - The process recommended consists essentially in steam-distilling the sample and extracting the benzoic acid from the distillate by means of ether.The apparatus used in the distillation is shown in the figure. About 10 grams of the sample are weighed into the inner flask, from 1-5 to 2 grams of solid paraffin are added, and the flask is attached to a condenser. Ten C.C. of concen- trated sulphuric acid are added, drop by drop, through the tapped funnel; the flask is agitated gently to mix the contents, and is allowed to stand for about ten minutes after the action of the sulphuric acid has ceased. One hundred and fifty C.C. of distilled water are now placed in the outer flask, which is attached to the inner flask as shown, and the water is brought gradually to boiling. One hundred C.C. of distillate are collected, filtered into a separating funnel, and the re- ceiver and filter are washed twice with about 10 C.C.of water. The filtered distillate and washings are then extracted three times with ether, using about 100 C.C. in all. The combined ethereal extracts are shaken out with several successive quantities of water, the ether is evaporated, and the residue is dried in a desiccator, and weighed. If desired, the crystals of benzoic acid obtained may be dissolved in alcohol and titrated with standard alkali solution. W. P. S. Estimation of Water in Cresol Soap Solutions. 0. Schmatolla. (Chein. Xeit., 1909,33, 284.)-The author points out that he was the first to suggest the use of acetic acid for the estimation of water in cresol soaps as described in the process proposed by Spalteholz (ANALYST, 1909, 153). Owing to the fact that commercial cresol soaps are prepared indiscriminately with alkaline, neutral, or acid sodium and potassium soaps, the results obtained by the process are only approximate.A good cresol soap should contain about 21 per cent. of fatty acids (as soap), and the cresol should be present in the free state, and not partially combined with excess of alkali introduced with the soap. (See also ANALYST, 1903, 27, 250.) w. P. s. The Freezing-Point of Wine as a Means of Determining its Alcoholic Strength. W. Mestrezat. (BuZI. SOC. Chirn., 1909,5, [iv.], 250-254.)-1t is shown that the freezing-point of a wine is directly related to the quantity of alcohol present, the other constituents being apparently without influence. As the result of the examina-229 THE ANALYSZ: tion of thirty-one samples of both red and white wines, the author finds that the ratio of alcoholic strength (percentage) to freezing-point (degrees Centigrade) is as 1 to 0.433.This ratio is a consta.nt for all practical purposes, the wines mentioned above, containing from 14.1 to 23.0 per cent. of total solids, yielding ratios lying between 0.42 and 047. Consequently, the alcoholic strength of a wine may be determined by taking the freezing-point of the sample and dividing the result by 0.433. The method will give the alcoholic strength of a wine within a limiting error of 0.3 per cent. w. P. s. Estimation of Volatile and Fixed Acids in Wine. J. Hortuet. (State of i7liw)Lesotn Dairy and Food Dept., Report, 1909, 10-11.) -The apparatus employed consists of a 300 C.C.flask with an elongated neck, into which is fitted, by means of A short section of thick rubber tubing, a cylindrical-shaped flask provided with a siphon- like tube, leading inwards from the bottom and bent back upon itself, so that the end reaches nearly to the bottom of the inner flask. The latter is connected to a con- denser by means of a bent tube and safety-bulb; the stopper of this flask also carries a small tapped funnel. One hundred C.C. of recently distilled water are placed ixi the larger flask, the small flask is fitted in the neck, and 10 C.C. of the wine are run in through the funnel. After rinsing the funnel with a little water, the tap is closed, and the water in the outer flask is heated to boiling. The steam passes through the siphon into the mine, and successive quantities of 50 C.C. of distillate are collected and titrated.The distillation is stopped when 10 C.C. of distillate require only 1 drop of & sodium hydroxide solution for neutralisation. The contents of the two flasks are then mixed and titrated in order to obtain the quantity of fixed acids in the wine. w. P. s. Estimation of Volatile Bases in Wine. P. Dutoit and M. Duboux. (Ann. de Chim. Anal. Appl., 1909, 14, 91-96.)-A method of estimating the total volatile bases in wine is based upon the variations in the electrical conductivity of the distillate containing them, after the addition of successive small quantities of acid. One hundred C.C. of the wine are mixed with 60 to 70 C.C. of 2 per cent. sodium hydroxide solution, and distilled until 100 C.C.of distillate have been collected. A measured quantity'of the distillate (30 c.c.) is placed in the electrolytic trough, and its conductivity determined a t 25" C. An addition of 0.05 C.C. of & hydrochloric acid is then made, and the electrical conductivity again determined. This operation is continutllly repeated, always after the addition of the same quantity (0.05 c.c.) of acid, until a sudden increase in the conductivity is observed, after which two or three more determinations are made to fix the exact point of alteration. The results are plotted in a curve, in which the abscism represent the amounts of acid added, and the ordinates the conductivities. The exact amount of acid required to neutralise the volatile bases may then be found graphically.To obtain the amount of volatile organic bases, it is necessary to deduct from the quantity of total volatile bases the amount of ammonia. This may be estimated by means of Nessler's reagent or by precipitation with platinum chloride. The quantity of ammonia in a normally fermented wine is fairly constant, ranging from 4 to 5 mgm. per litre. The organicTHE ANALYST. 223 volatile bases, however, vary very greatly, the amounts found in fifty samples of different kinds of wine ranging from 0.06 to 0.25 gram per litre. C . A. M. Value of the Polenske Test in the Analysis of Oils and Fats. R. R. Tatlock and R. T. Thornson. (J. SOC. Chem. Ind., 1909, 28, 69-72.)-The im- portance of carrying out the Polenske test in its minutest details without variation is insisted on in this paper.Even variations in the amount and fineness of the pumice employed cause differences in the figures obtained with the same sample, varying from 2.0 (insoluble volatile acids) to 2.9 c.c., the first figure being obtained by using two small lumps of pumice, and the latter figure with 1 gram of No. 2 pumice powder (tie., passes through a sieve with 2,500 meshes to the square inch, but remains on a sieve with 3,600 meshes). This last powder, in a quantity of 0.1 gram, is the amount and fineness recommended. The authors were unable to trace any close relationship between the soluble and insoluble volatile acids. Of the whole series of twenty-four samples of genuine butter-fat, the variation in soluble volatile acids (Reichert figure) was from 24.1 to 32.4 c.c., with an average of 28.5 C.C.; while the variation in insoluble volatile acids (Polenske figure) was from 1.0 C.C. to 4.2 c.c.-average, 2.4 C.C. The following results were obtained on the analysis of butter, cocoanut oil, and mixtures of these, the same products being used to make all the mixtures : Soluble Insoluble Volatile Acids. Volatile Acids. Butter alone ... I . . ... ... ... 28.1 ... 1.8 Cocoanut oil alone ... ... .. 1 ... 7-5 ... 18.0 Butter with 5 per cent. cocoanut oil ... 27.4 ... 2.4 7 9 10 ... 26.2 ... 3.2 9 7 20 ... 24.4 ... 4-2 9 , 30 ... 22.5 ... 5.7 1 , 40 9 9 9 , ... 20.9 ... 7.4 From these figures, the possibility of detecting even 10 per cent. of cocoanut oil in butter by the Polenske test is doubtful, and the authors have themselves extracted from milks butter-fat giving 29.4 C.C.of soluble and 4.2 C.C. of insoluble volatile acids. (This figure was probably caused by the cow yielding the butter having been fed partly on cocoanut cake, and experiments in this direction support this view.) The amount of soluble and insoluble volatile acids contributed by each con- stituent of a mixture of cocoanut oil and butter was determined : 2 , 9 9 9 , >, 9 , 9 9 Soluble Insoluble Volatile Acids. Tolatile Acids. 4 grams butter-fat ... ... ... ... ... 22-6 1.7 1 gram cocoanut oil ... ... ... ... ... 4.4 9.1 Mixture of 4 grams butter with 1 gram cocoanut oil.. . 24-4 4.2 Thus, there is a deficiency of 2.6 of soluble and 6.6 of insoluble acids, no doubt due to the retention of the less volatile acids by the non-volatile acids.I t is also seen that 1 gram of cocoanut oil gives 4.4 of soluble acids, while 5 grams of the same oil gave only 7.5. In this connection the following experiments were devised: After the 110 C.C. of distillate had been obtained in the usual way, from 1 gram of butter224 THE ANALYST. and 1 gram of cocoanut oil, saponified and distilled separately, a further 110 C.C. of water was added to each flask, and the distillation continued until 110 C.C. was again distilled, and this process was repeated several times. The following are the authors’ results : 1st distillation ... 2nd 1 ) ... 3rd , I ... 4th 9 , ... 5th 1 , ... 6th ?, ... 1 Gram Butter. Soluble Volatile Acids. Insoluble Volatile Acids. 6.2 0.6 0.2 0.1 0.05 0.05 7-20 1.0 0.8 0.6 0.6 0.5 0.5 4.0 Gram Cocoanut Oil.Soluble Volatile Acids. 4.4 0.7 0.2 0.15 0.10 0-05 5-60 Insoluble Volatile Acids. 9.1 5.6 4.3 3.0 2.7 2.3 27.0 The differences in the quantity of soluble acids coming over when 1 gram is taken and when 5 grams are distilled is undoubtedly due to the fact that the ‘‘ insoluble ” volatile acids are only insoluble under the conditions of the original process, and are actually slightly soluble in water, as was proved by direct experiment. The following figures were obtained with mixtures of margarine and cocoanut oil : Soluble Insoluble Volatile Acids. Volatile Acids. Margarine alone ... ... ... ... 0-4 .. 0.5 ,, + 5 per cent. cocoanut oil ... 1.4 0-7 7 7 +I0 9 7 ? ? ... 2-2 1.3 1 1 +20 ,, 1 ) ... 3.9 2.6 7 ) + 30 , j 7 7 ...5.0 3.9 7 , +50 y 7 > 1 ... 6.5 7.6 Y 9 +40 7 7 7 1 ... 5.8 5.7 I t is apparent that the soluble acids in the margarine containing 20 per cent. of cocoanut oil are 0.8 and the insoluble acids 6.9 lower than the mixture would be expected to give, showing in this case also that these volatile acids are retained by the non-volatile fatty acids. Similar results were obtained with olive oil and beef-fat mixed with cocoanut oil, the almost liquid fatty acids of olive oil having quite as great an effect in retaining volatile acids as the more solid acids of beef-fat. The authors recommend extreme caution in coming to any decision as to the presence of cocoanut oil in butter, from the results of the Polenske test. The doubtful point is when a ratio of 9 of insoluble volatile acids to 100 of soluble acids is obtained.In these cases the phytosteryl acetate test should be employed in addition, and if proof of the presence of a vegetable oil is yielded, the probability is that it is cocoanut oil. In such a case it is safe ,to regard any excess of insolubleTHE ANALYST. 225 volatile acids as due to cocoanut oil, and the minimum proportion should be stated. No reliance can be placed on the silver, copper, or barium values of these mixtures of fats as a means of detecting cocoanut oil. The Polenske figure is apparently reliable within limits of about 5 per cent. for determining cocoanut oil in margarine. The analyst should avoid an obvious pitfall here, there being a danger of returning a margarine giving 6.4 of soluble volatile acids as containing 16 per cent.of butter, if the Polenske figure were not taken into account. A sample of margarine examined by the authors gave 6-2 of soluble volatile acids and 6.6 of insoluble acids, but the greater portion of the soluble acids was due to cocoa- nut oil. The application of the Polenske test to the determination of animal fats such as beef-fat or lard in butter, and for the examination of such animal fats generally, has not as yet proved of any positive value. The following results have been obtained : Bee f-fa t ... Lard ... Cotton-seed oil" Olive oil ... Arachis oil ... Cod-liver oil ... Dogfish- liver oi Porpoise oil ... Japan wax ... Soluble Volatile Acids. ... ... ... 0.35 ... ... ... 0.35 ... ... ... 0.40 ... ... ... 0.20 ...... ... 0.40 ... ... 0.50 ... ... ... 0.30 ... ... -.. 81.40 ... ... ... 3-60 Insoluble Volatile Acids. 0.30 0.40 0.40 0.20 0.35 0.40 0.90 1.40 0-90 Incidentally the authors have noted that the soluble volatile acids for 5 grams of butter fat may be obtained approximately by multiplying the result from 2.5 grams by 1.92, and tha from 1 gram by 4.5. Similarly, the insoluble volatile acids for 5 grams may be obtained by multiplying the result from 2.5 grams by 1-16, and that from 1 gram by 1.6. A. R. T. A Rapid Method of Estimating Fixed Organic and Volatile Acids in Wines and Fermented Liquids. E. Pozzi-Escot. ( A m de Chim. Anal. AppZ., 1909, 14, 99-100.)--The total acidity of the wine, etc., is estimated by titration, with phenolphthalein its indicator. The acidity due to the fixed acids is then found from the difference between the alkalinity of the ordinary ash of the wine and the alkalinity of the ash left from the ignition of the barium salts of the fixed acids. In making au estimation, 100 C.C. of the sample are evaporated to 2 to 3 c.c., the residue taken up with 96 per cent. alcohol, the filtrate evaporated, and the alkalinity of the ash left on ignition determined by titration wit;h nitric acid, with helianthin as indicator. The result is expressed in terms of sulphuric acid. Another portion (100 c.c.) of the original wine is neutralised with barium hydroxide and evaporated to 2 or 3 C.C. The residue is treated with 100 C.C. of 96 per cent. alcohol containing 2 per cent. of barium bromide. The fixed acids (with the exception of lactic acid) are immediately precipitated, whilst the volatile acids (formic, acetic, propionic, butyric, and valeric acids) remain in solution. The liquid is filtered, the precipitate washed with strong alcohol and ignited, and the alkalinity of the ash determined and expressed as before226 THE' ANALYST. in terms of sulphuric acid. The difference between the two results gives the acidity due to the fixed acids, whilst the difference between the acidity due to the fixed acids and the original acidity of the wine gives that due to the volatile acids. The method does not give accurate results in the presence of lactic acid, which, however, is seldom present in wines. Mineral acids, if present, are estimated as volatile acids. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9093400212

出版商:RSC    

年代:1909

数据来源: RSC

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226 THE' ANALYST. BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. A Burette for Use in Bacteriology. P. Suchy. (German Pat., 205,708, of 1907; through Cl~ern. Zed. Rep., 1909, 33, 118.)-The burette consists of a glass tube, a (see figure), of such size that it will fit into the holder of a centrifugal machine. A glass rod, b, passes down the centre of the burette, and forms a ground-in joint with the bottom of the latter, as shown at f. The portion of the glass rod forming this joint is made slightly conical-for instance, the upper part of the cone may be 8 mm. and the lower part 7 mm. in diameter in order to with- stand the pressure when in the centrifugal machine. When a liquid is submitted to centrifugal action in this burette, any sediment will collect in the space c, and may be discharged through the capillary v by rotating the rod until the upper end of the capillary is in connection with the space e .The lower end of the capillary, at g, is 1 mm. in diameter and about 1.5 mm. at the upper end. w. P. s. Detection of Tuberele Bacilli in Sputum. V. Ellermann and A. Erlandsen. (Zeit. Hygiene, 1908, 61, 219; through Chern,. Zeit. Bep., 1909, 33, 117.)-The following methods for separating the bacilli are recommended : From 10 to 15 C.C. of the sputum are mixed in a corked tube with from 5 to 7.5 C.C. of 0.6 per cent. sodium carbonate solution, and the mixture is kept at a temperature of 37' C. for twenty-four hours. The greater part of the supernatant liquid is then decanted, and the lower portion is submitted to centrifugal action; the sediment, after the removal of the liquid portion, is then ready for examination.Or 1 volume of this sediment may be mixed with 4 volumes of 0.25 per cent. sodium hydroxide solution, the mixture heated to boiling, and again submitted to centrifugal action. w. P. s. Standardisation of Disinfeetants. .H. Chick and C. J. Martin. (J. Hygiene, 1909, 8, 654-697, 698-703 ; J . Chenz. Soc., 1909, 96, 171-172.)-Standardisation tests must be carried out under constant conditions of temperature, culture medium, number of bacteria per unit volume, and duration of observation. A logarithmic relationship exists between the strength of the disinfectiug solution and the rate of disinfection. I n standardising metallic salt disinfectants, the traces carried over with the test sample must be neutralised by sulphide.I n the case of mercuric chloride, an excess of sulphide is necessary to decompose a compound of the salt and the substance of the living organism employed.THE ANALYSTb 227 Some disinfectants are more efficient against a particular organism than against any other. Metallic salts are most efficient against sporesz and, as a rule, virulent organisms are most resistant to the action of disinfectants, A non-virulent strain of Bacillus typhosus is the best to employ in standardisation tests. The presence of 10 per cent. of blood-serum reduces the efficiency of a 1 per cent. phenol solution by about 12 per cent., while the effect on emulsified disinfectants is somewhat greater. The presence of finely particulate matter affects the germicidal value of emulsified disinfectants containing the higher phenols to a greater extent than it affects phenol solutions; the finer the emulsion, the more seriously is its value reduced by such particulate matter.The removal of an emulsion of higher phenols by organisms is at first a process of adsorption, and, because of this, the organisins become surrounded by a concentrated disinfectant, and so disinfectants of this class possess superior efficiency. A. R. T. Micro-Organisms Present in Sewer a r and in the Air of Drains. F. W. Andrewes. (Report of the Medical O$icer to the Local Government Board, 1906-07, p. 183.)-The investigation was designed to answer the question whether sewage does specifically pollute the air of sewers and drains with its own bacteria.Special search was made for members of the streptococcus and B. coli groups. The method used was to expose large plates of the selective media of Conradi and Drigalski and of hlacconkey for various times in the air to be examined, and then to the colonies developing to apply the fermentation tests of Gordon for streptococci and of MacConkey for B. coli. I t was found that streptococci could be isolntedfrom sewer and drain air corresponding mainly with the X. salivarius type, which is the most abundant and characteristic streptococcus of sewage, whereas the most abundant and characteristic streptococcus found in the fresh air of London was the type S. eqziiizz~s. I t was possible to isolate readily from the air of a large drain numerous members of the B.coli group, which closely corresponded in their biological characters with those of the sewage flowing along the drain; whilst from the fresh air in the vicinity the same bacilli could only be obtained in very small numbers. From experiments with sewage specially inoculated with the B. prodigiosus it was proved that in the drainage system of an ordinary private house sufficient splashing occurs to permit of the ready disengagement of bacteria from material passing down soil-pipes, and that such disengaged bacteria can be carried along a 4-inch drain against the flow of sewage for a distance of at least 50 feet by ventilation currents. The question originating the research was, therefore, answered in the affirmative. J. H. J. Estimation of Creatinine in Urine.G. Edlefsen. (Jfiiizclz. nzed. WOC~Z., 1908, 55, 2524-2527 ; J. Chem. Soc., 1909, 96, 276.)--1. The urine, previously freed from phosphates and sulphates by means of a solution of a barium salt, is treated with dilute sulphuric acid in presence of alcohol and ether. The precipitated creatinine compound is dissolved in water and titrated with barium hydroxide solution, using phenolphthalein as indicator : 0.396 SO, = 0.604 creatinine. 2. The urine is first freed from urea by means of mercuric nitrate solution, and228 THE ANALYST. 10 C.C. of the urine thus treated are mixed with 5 C.C. of a 1 per cent. solution of salicylic acid. The excess of the latter is determined by extracting it with ether and titrating with sodium hydroxide : 22 parts of salicylic acid combine with 78 parts of creatinine.A. R. T. Detection and Estimation of Potassium Chlorate in Urine. J. F. Virgili. (Revista Real. Acad. Ciencias Madrid, 1908, 7, 214; through Chem. Zeit. Rep., 1909, 33, Il7.)-The aniline test, described previously by the author (ANALYST, 1909, 69), may be employed for the detection and colorimetric estimation of chlorates in urine. When the aniline reagent is added to urine containing but a small quantity of chlorate, a purple coloration is produced, and is due to the action of the liberated chlorine on the colouring matter of the urine. I n the presence of larger amounts of chlorate, the purple colour is further oxidised to a yellow compound, and the excess of chlorate then reacts with the aniline to give a blue coloration; the resulting coloration is green. The estimation of the chlorate may be carried out as described (d~id.). When the urine contains not less than 2 mgms. per C.C. of chlorate, and not more than 2.5 mgms. (if more be present, the urine must be diluted), the coloration obtained is compared with that produced by known quantities of potassium chlorate mixed with normal urine free from chlorate. If the urine contains only small amounts of chlorate, it is better to add a known quantity of chlorate, as the purple coloration is not suited to comparison with the standards ; the quantity of chlorate added is, of course, deducted from the result obtained. In exceptional cases, where it is necessary to clarify the urine before applying the test, care must be taken to similarly clarify the urine used in the standard solution. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9093400226

出版商:RSC    

年代:1909

数据来源: RSC

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228 THE ANALYST. ORGANIC ANALYSIS. Estimation of the Acidity of Soils. R. Albert. (Zeit. angew. Chem., 1909, 22, 533-537.)-1n the method proposed the soil is treated with bariuni hydroxide, and the excess of the latter estimated by distillation with ammonium chloride. The difference gives the amount of barium hydroxide neutralised by the acids of the soil. From 20 to 50 grams of the air-dried soil are mixed in a Jena flask of about 1 litre capacity with 200 C.C. of distilled water ; a definite volume (from 50 to 100 c.c.) of standardised barium hydroxide solution is added from a burette, and 10 grams of solid ammonium chloride are then introduced, The contents of the flask are boiled, after the flask has been attached to a condenser, and the ammonia liberated is collected in a receiver containing a known quantity of standard acid.The distillation takes about twenty-five minutes, and, after the excess of acid in the receiver has been titrated, a simple calculation gives the quantity of barium hydroxide which has been used to neutralise the acids present in the soil ; these acids may be expressed as grains of carbon dioxide per 100 grams of soil. Barium hydroxide was found to be preferable to calcium oxide or inagnesium oxide, as the calcium and magnesium compounds formed are partially dissociated by boiling, and the excess of magnesia is, moreover, liable to form a non-volatile compound with the ammonia. Two colorimetric tests are described, which give a rough idea of the amount ofTHE ANALYST. 229 Acidity : Grams of CO,.acidity in a soil: the first depends on the brown colour produced with an aqueous infusion of the soil, treated with lithium phosphate (Li,PO,), and the second depends on the blue colour obtained on treating a filtered extract of the soil with a mixture of potassium iodate and iodide, and adding starch solution. The following table gives the results obtained on the examination of certain soils by the above-mentioned methods, as well as results obtained by the modification of Tacke’s process, described by Siichting (ANALYST, 1909, 162) : Colour Test. Kind of Soil. Soil from field ... .. 9 9 9 , 9 9 9’ - a - Uncultivated soil . . Mountain soil . . . .. New Method. 0.060 0-058 0.070 0.088 0.768 Suchting’s Method. 0-058 0.055 0.068 0.078 0.515 With Li,PO,. Light brown Brown Dark brown Brownish-black , 9 With Iodide -t Iodate.Light blue. Blue. Deep blue. Dark blue. 9 , The colour tests were carried out on 3 grams of the soil in each case. w. P. s. A Modification of Halphen’s Reaction. L. Garnier. ( J . Pharm. Chim., 1909,29,273-274.)-To obtain concordant results in this test with oils containing the same proportion of cotton-seed oil, it is necessary to have an excess of sulphur in an undissolved form. The colorations are then proportional to the amount of cotton- seed oil, and a colour scale may be made with an inactive oil (poppy oil) containing from 5 to 75 per cent. of cotton-seed oil, Carbon bisulphide, containing 2 per cent. of powdered stick sulphur, is used in the test, the liquid being shaken immediately before being mixed with the oil and the amyl alcohol.reflux condenser, and heated for an hour in a water-bath, after which it is cooled, and its contents made up to the original volume and transferred to test-tubes, which are corked and kept in the dark. The tube is connected with C. A. M. The Examination of Carbon Tetrachloride. L. G. Radcliffe. (J. SOC. Chem. Id., 1909, 28, 229-230.)-The author recommends the following modification of the method of Gastine (Comptes Bend., 98, 1588) for the determination of carbon disulphide in commercial carbon tetrachloride, the method depending on the con- version of the impurity into potassium xanthate and titration of this compound with decinormal iodine solution. A loosely corked flask containing 25 C.C. of alcoholic potash is weighed, and about 1 C.C.of the sample introduced from a pipette, which is held, during delivery, close down to the level of the alkali. After reweighing the corked flask and contents, and allowing the mixture to stand for five minutes, the liquid is rendered slightly acid to phenolphthalein with dilute acetic acid, and after diluting with water and cooling, is treated with an excess of solid sodium bicarbonate,330 THE ANALYST. I which dissolves, forming a milky liquid. This liquid is then titrated with iodine solution, using starch as indicator. The end reaction is sharp, and the following results were obtained in a series of tests : CS, present 100 per cent., found 100 per cent. by above method; present 3.89, found 3.81 per cent. ; present 5.53, found 5.42 per cent.; present 8.96, found 8.94 per cent.; present 11.3, found 11-3 per cent.; present 16.0, found 15.88 per cent. The reaction of the freed santhic acid with the iodine in the titration is as follows : 2C3H60S, + I, = C,H,oO,S, + 2HI. The following results were obtained by the examination of a sample of com- mercial carbon tetrachloride, and of pure samples of this substance and of carbon disulphide : Specific gravity at 15.5" C. ... [nID a t 18" C. .. . . .. ... Fractional Distillation of 100 C.C. : 10 C.C. ... ... ... 20 C.C. ... ... ... 30 C.C. ... ... ... 40 C.C. ... ... ... 50 C.C. ... ... ... 60 C.C. ... ... ... 70 C.C. ... ... ... 80 C.C. ... ... ... 90 C.C. ... ... ... 97 C.C. ... ... ... One drop ... ... ... Commercial CCl,. 1-591 1,4678 Boiling Point "C.67.0 74.0 75.0 76.3 77.3 77.8 75.0 78.0 78.0 78.0 78.0 n]D, 18" c- - 1.4791 1.4773 1.4716 1.4667 1.4637 1.4625 1.4617 1.4618 1.4619 1.4620 Pure CCI, (Kahlbaum). Pure CS, (Kahlbaum). 1.606 1.4621 Boiling Point "C. 76.0 77.8 78.0 78.0 78.0 78.0 78.0 78-0 78.0 78.0 78.0 n ] ~ , 18" C. - 1,4615 1.4616 1.4616 1.4617 1.4617 1.4618 1.4619 14617 1.4618 1.4619 1.272 1.62981 Boiling. Point "C . 45.6 45.9 45.9 45.9 45.9 45.9 45.9 46.0 46.2 48.0 48-0 ?&ID, 18" c. - 1.6293 1.6298 1.6296 1.6294 1.6295 1.6295 1.6294 1.6292 1.62887 1,62887 A sample of carbon tetrachloride containing 3.05 per cent. of carbon disulphide was tested in Abel's flash-point apparatus, but this proportion of impurity could not be detected by its means. A. R. T. A Modification of Buignet's Method of Estimating Hydrocyanic Acid.G. Guerin and L. Gonet. (J. Phnrm. Chznz., 1909 29, 234-236.) -Buignet's method of estimating hydrocyanic acid by titration with copper sulphate solution in the presence of ammonia has long been akandoned, owing to the uncertainty in determining the final change of coloration. This drawback may be obviated by the addition of a small amount of sodium sulphite, the end-point of the reaction being then perfectly sharp. Numerous test estimations made by the authors show that the formula given by Buignet ( J . PlLnmz. Chirn., 1859, [iii.], 35, 168j ought to be modified as follows : CUSO, + 3NH,.CN = (NH,),SO, + [Cu(CN),NH,.CN].THE ANALYST. 23 I Distillation : Began to distil a t Distillate below 100" C.'% Distillate between 100" ...Distillate between 120" ... Distillate above 133" C. % and 120" C. % ... and 133" C. % ... Each 0.1 C.C. of a standard solution of copper sulphate containing 30.81 grams per litre of the pure recrystallised salt corresponds to 1 mgm. of hydrocyanic acid. I n estimating the hydrocyanic acid in cherry-laurel water, 25 C.C. of the sample are diluted with 75 C.C. of water and mixed with 10 C.C. of ammonia solution and 20 drops of sodium hydroxide solution (strength not mentioned), and 0.5 gram of sodium sulphite dissolved in the mixture. The liquid is then titrated with the copper sulphate solution until there is a permanent blue tint. The method gives accurate results in the estimation of aqueous solutions of hydrocyanic acid, but the addition of sodium hydroxide (used to prevent the formation of hydrobenzamide in cherry-laurel waterj is not necessary.C. A. M. 70" c. 39-48 37-49 7.5-11.5 2.5-3-5 Composition of Commercial Petrols. B. Blount (paper read before the Incorporated Institute of Automobile Engineers, March 10, 1909.)-The author has examined some of the leading makes of petrol in order to ascertain what variations occur in the composition of the article, and what limits may be laid down in fairness to the maker, and for the protection of the consumer. Samples representing seven digerent brands were bought at various shops and garages in London, and the results of the analyses are given in an abridged form in the following table : Cnlnrlfic Value : Calories per litre . . . . , . kilo ... ... Britiih thermal units per T$ gallon ...... British thermal units per lb. ... ... ... Sulphur % ... ... 8249 11162 14845 20092 0'03 -4- & A d &I2 04 a ?2cg 2 : Z m 5:: d b.cR 0.700 56" C. 86.5 11.5 - 0.5 7911 11 302 14240 20344 0.06 Trade Name. 0-736 0.739 Specific gravity ... ...I to 0.716 to 0.719 0.717 i0-65" C, 65-69 21-26'5 4 -5-8 -0 2.5-4.6 i0-65" C 59-70 24-28.5 8 -0-7 ?I 1'5-5.0 58" c. 68'0 22 *5 6 5 2.0 63" C. 59.0 29.0 8.0 3.0 3-65" C. 64-68 22-26 5-5-6.5 3.5-3.5 5-58" c. 58-73 7 *5-24.5 5.0-9.5 3.0-6.5 60" C. 74.0 15.5 5.0 4.0 8068 11252 14522 20254 0.06 8051 11229 14492 20212 trace SO42 11200 14476 20160 - 8021 11187 14438 20137 0.07 8056 11267 14501 20281 0 -07 7919 11232 14253 20218 0.06 The calorific value was determined by means of a bomb calorimeter. In spite of the fact that there was an ample excess of oxygen at a pressure of 25 atmospheres in the bomb, complete combustion was difficult to secure, and in the first experi- ments the explosion was so violent as to shatter the platinum cup in which the petrol was contained.,4 device described by Berthelot was therefore adopted. The petrol was enclosed in a relatively deep cup provided with a celluloid envelope rising above232 THE ANALYST. the edge of the cup, and contracted at the top so as to form a sort of sack with a narrow mouth. The vapour was thus confined sufficiently to cause it to burn at a moderate rate, and violent explosions were avoided. A small correction was made for the heat of combustion of the celluloid shell. I t will be seen from the above results that petrol of recognised brands is fairly uniform in quality, that there is no great difference between three of the brands, but that there are certain others of equal standing which are sharply differentiated from the foregoing. I t is evident that narrow limits cannot be laid down in a specification relating to the quality of petrol.w. P. s. Indicators and Stabilising Agents for Smokeless Powders. A. Carneiro. (Zed. fur das Ges. Schiess. m d Sprengstofwesen, 1909, 4, 29.)-Diphenylamine is incorporated with some German smokeless powders to act as an indicator and stabilising agent. Such indicators give a false sense of security and may lead to neglect of regular tests, and the following results show that as a stabilising agent diphenylamine is worse than useless, as it actually lowers the stability.Four nitro- cellulose powders, A, B, C, and D, were submitted to Guttmann's test at 80" C. on 1-gram portions. After a preliminary heating for 72 hours at 38" C., A gave 9, B log, C 11, and D 11 minutes, increases of 3, 18, 5 and 43 minutes. The same powders incorporated with 1 per cent. of diphenylamine gave : A 8 minutes, B 9, C 9, and D 74 minutes. After pre- liminary heating A gave 8+, B 10, C 9, and D 8 minutes, increases of only Q, 1, 0, and 4 minute. The lowering of stability due to the diphenylamine is shown by these smaller increases, and by a comparison of the tests with preliminary heating. Four nitroglycerine powders, A, B, C, and D, tested similarly, but at 70° C., gave : A 22, B 314, C 334, and D 394 minutes ; and with preliminary heating, A 18, B 28, C 284, and D 29 minutes, decreases of 4, 38, 5, and lo& minutes.The same powders incorporated with 1 per cent. diphenylamine gave : A 15, B 344, C 36, and D 404 minutes ; or with preliminary heating, A 16, B 24, C 244, and D 28 minutes, greater decreases of 9, 104, l l g , and 12$ minutes. The lowering of stability is shown by these greater decreases, and by a comparison of the tests with preliminary heating. The author proposes to investigate other organic bases used for the same purposes. 0. E. M. A gave a test of 6 minutes, B 9, C 6, and D 6& minutes. A Liquid Resin from Pine-Wood. W. Fahrion. (Zeit. angew. Chem., 1909, 22, 582-583.)-1n the preparation of cellulose from Swedish pine, a liquid resin, termed tallol, is obtained as a by-product.This is a dark brown, fairly mobile liquid, which does not solidify at -20" C. It dissolves readily in alcohol, ether and acetone, but is not completely soluble in petroleum spirit and turpentine oil. I t s boiling-point under a pressure of 40 mm. is fairly constant at 270" C. When spread in a thin layer upon glass it takes several months to solidify, but the salts that it forms with heavy metals are soluble in petroleum spirit and turpentine oil, and rapidly form dry films. A sample of tnllol gave the following values: Specific gravity at 15" C., 0.997 ; acid value, 163 ; saponification value, 179 ; and iodineTHE ANALYST. 233 Value, 118. The author concludes from his analyses that the resin is closely related to colophony, and that it consists chiefly of one or more resin acids of the formula C,,H,,O,.One of the acids present is a solid, and ta.ZZoZ must therefore be regarded as a solution of a solid resin acid in a liquid one. C. A. M. Estimation of Resin in Sulphite Pulp. E. Opfermann. (Zeit. angelo. Chem., 1909, 22, 436.)-The author shows that in the estimation of resin in sulphite pulp, extraction with alcohol yields results much higher than are obtained by extraction with ether. I n nine samples of different origin the quantity of alcoholic extract obtained was 40 to 100 per cent. higher than that of ethereal extract. The latter only can be regarded 8s the true measure of the resin content. A. G. L. Optical Estimation of Mixtures of Sucrose and Hydrated Maltose. J.Pierraerts. (B-zdl. dssoc. Chim. Sucr. et Dist., 1909, 26, 650-652.)-Twenty-five grams of the mixture are dissolved in 40 to 50 C.C. of warm water, and the solution cooled and made up to 100 C.C. For the direct polarisation 25 C.C. of this solution, A, are treated with 2 C.C. of alumina cream and 2 drops of strong ammonia solution, and the liquid made up to 50 c.c., filtered and polarised in a 200 mm. tube. For the hydrolysis 50 C.C. of A are mixed with 10 C.C. of a freshly prepared 20 per cent. solution of citric acid in a round-bottomed flask, into which are also introduced some fragments of pipe. The flask is connected with a reflux condenser and heated over wire gauze, so that its contents are brought to boiling-point as rapidly as possible. The boiling is continued for exactly eight minutes, after which the flask is rapidly cooled and its contents defecated as before, diluted to 100 c.c., filtered, and polarised.From the readings before and after inversion the respective amounts of sucrose and hydrated maltose may be found by means of the equations- 2 66.5 -x+2-y=a, 130 100 100 19.80 130 95 100 2- x + 2-y = a', where a and a' represent the polarimetric readings before and after inversion respec- tively; x the quantity of sucrose in 100 C.C. of solution B ; y the quantity of hydrated maltose ; + 66.5" the specific rotation ([a],,,~) of sucrose ; + 130" the specific rotation ( [ U ] ~ ~ ~ O ) of hydrated maltose ; and - 19.80" the specific rotation ([alDm0) of inverted sugar for a maximum concentration of C = 1.25 grams per 100 C.C.(Gubbe). By resolution these equations give to II: and y the following values : x = 0.57246 (a - a') ; y = 0.3846154 u - 002928363 ( a - u'). The results multiplied by 80 give the proportions of sucrose and hydrated maltose in 100 grams of the mixture of sugars analysed. The accuracy of the method is shown by a series of test analyses given in tabular form. C . A. M. The Relative Quantities of Organic Acids in Tobaceo before and after (Chem. Zeit., 1909, 33, 338-339.)-The leaves of average Fermentation. J. Toth.234 Moisture. THE ANALYST. Total Organic Acids (as Oxalic Acid) in the Dry samples of ten different kinds of fresh tobacco were freed from the middle rib, so 8s to give two equal portions. One of these was analysed at once and the other after fermentation.The loss in weight of the dry substance during fermentation ranged from 0.26 to 5-58 per cent., the average being 3.25 per cent. The amount of total organic acids (as anhydrous oxalic acid) in the dry substance was increased by fermentation from 0-62 to 3.01 per cent., with an average increase of 1.59 per cent., whilst the volatile organic acids (in terms of oxalic acid) in some cases showed an increase (averaging 0-59 per cent .), and, less frequently, a decrease (averaging 0.63 per cent.). In most cases there was an increase (averaging 0.35 per cent.), whilst in other cases there was a decrease (averaging 0.28 per cent.). The amount of volatile organic acids, after deduction of oxalic acid, showed in some cases an average increase of 0.66 per cent., and in others an average decrease of 0.49 per cent. When a tobacco contains more than 3 per cent.oxalic acid, at least three or four evaporations are required to remove the whole of it, instead of two evaporations, as previously stated (Chem. Zeit., 1908, 32, 242). The following results are typical of those obtained in the analysis of a large number of samples : Similar variations were observed in the amounts of oxalic acid. Tobacco. Debrecziner Tizaer ... Garden, me dium fine- ness ... Before Fermen- tation. Per Cent. 20.00 21.15 14-84 I Hubstance. I After I After. Per Cent. 10.60 10.06 11 -37 Volatile Organic Acids (as Oxalic Acid) in the Dry Substance. I I Constants of Jasmine Flower Wax. Oxalic Acid in Dry Substance. I Volatile Organic Acids less Oxalic Acid found.v'olatile Organic Acids (as Acetic Acid). Before. Per Cent. 3 '42 1'13 2.02 After. Per Cent. 1 -65 3'11 1 -37 C. A. M. L. G. Radcliffe and J. Allan. ( J . SOC. Chem. Ind., 1909, 28, 227.)-The authors have given this name to the faintly odorous, hard, yellowish-brown '' wax " obtained as a product of the cooling of the alcoholic solution of the petroleum-ether extract of jasmine flowers. The alcohol-free " wax " had the following constants : Solidifying-point, 56' to 57' C. : Zeiss butyrometer scale-readings, at 84" C. = 30 ; at 74', 33 ; at 70°, 36 ; at 65", 38 ; at 62', 40 ; at 60', 42; and at 56', 44; acid value (solution in alcohol and ether), 2.8 mgms. KOH per gram of wax; saponification value (solbtion in amyl alcohol boiled five hours with alcoholic KOH), 65.8 (using sodium ethylate, 63); iodine value (Wijs), 52 to 53 per cent.The fatty acids gave the following figures: Mean molecular weight = 398 ; iodine value, 39 per cent. ; melting-point, 57" to 65" C. (slowly). The unsaponifiable matter yielded from ether a crystalline body melting at 64" C., which contained alcohols, but, owing to the small amount isolated, it was not further examined. A. R. T.THE ANALYST. 235 Estimation of Weighting in Silk. P. Heermann. (Farber-Zeit., 1909, 20, 75-78.) - The N-potassium hydroxide solution used in Ristenpart's method of extracting '( monopol black " from weighted silk (F&rber-Zeit., 1907, 18, 273-294 1908, 19, 34-35) has the drawback that the alkali has too solvent an action upon certain weak kinds of silk. This may be obviated by adding glycerin to the alkali solution, the fibres then remaining practically unaffected. The reagent used by the author for this purpose consisted of a mixture of equal parts by volume of N-potassium hydroxide solution and glycerin (28'). The fibres are heated with this solution to 80' C., and the beaker then left for five to ten minutes longer in the water-bath after removal of the flame. In this way the black dyestuff is completely extracted without loss of fibre. The reagent will also extract Prussian blue from silk, yielding a solution from which the dyestuff may be precipitated by the addition of an acid. This affords a rapid means of detecting Prussian blue, and of separating iron in that form from other iron compounds (oxide, tannate, etc.). Thus the ash of a silk weighted with Prussian blue was 9-56 per cent., xhilst, after ten minutes extraction at 80" C. with glycerin alkali, the ash of the residual silk was 0.43 per cent. In the case of silks containing (in addition to Prussian blue) tin phosphate, tin oxide, etc., it is advisable to extract the silk first with the glycerin alkali solution, then with cold 20 per cent. hydrochloric acid, and again with glycerin alkali. Even then the extraction may not be complete, and in such cases an estimation of the nitrogen will be found the best method. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9093400228

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 235 INORGANIC ANALYSIS. A Rapid Method for Estimating Carbon Dioxide in the Atmosphere. S. H. Davies and B. G. McLellan. (J. SOC. Chem. Ind., 1909, 28, 232-234.)- The authors’ method is based upon those of Angus Smith and Lunge and Zeckendorf, in which the quantity of air required to decolorise a known volume of standard baryta-water is noted. The pump used by the authors is fitted with inlet and outlet valves, and delivers 50 C.C. of air at each full stroke, and the inlet side is connected to a long glass tube supported by a clamp, so that air may be taken at a distance from the operator. The outlet is connected to the absorption vessel, in which 2 drops of phenol- phthalein solution are placed, followed by 25 C.C. of the weak standardised baryta solution run through a tube in the stopper of the vessel.The baryta-water is standardised against fresh air, taking this as containing 3.5 parts CO, per 10,000 of air. The stock solution of baryta is prepared by dissolving 25 grams of pure crystallised powdered barium hydroxide in 1 litre of distilled water, and storing in a suitable bottle fitted with tubes holding a measuring burette and soda-lime tube. Another bottle is used for storing the weak standard baryta, which is prepared by adding to 2 litres of distilled water containing a little phenolphthalein solution the strong baryta solution a few drops at a time, until, after well shaking, the pink colour is just permanent. A further addition of 3.3 C.C. of the strong baryta solution236 THE ANALYST. is made, the mixture shaken, and the weak solution thus prepared standardised in the absorption-vessel, For this purpose the apparatus is placed on a table in front of an open window on the windward side of a room, the open end of the inlet-tube projecting some feet out of the window.The apparatus is washed out with fresh air by working the pump several times. Into the absorption vessel is then admitted a little phenolphthalein solution, followed by baryta as already described. The baryta is conveniently transferred to the absorbing vessel from the containing bottle by means of a small hand-blower. The absorbing vessel is shaken thoroughly for fifteen seconds, and this is counted as 1 volume of air. Fifty C.C. of fresh air are then pumped into the vessel by one stroke, and the shaking, etc., repeated as often as is necessary until the coloured baryta is just decolorised, the number of strokes being duly noted.The strength of the weak baryta employed in the tests should be such that fifteen strokes (fourteen of the pump plus one for air originally in absorbing vessel) decolorise 25 C.C. If too weak or too strong, a fresh solution is made, using more or less of the strong baryta as required. The solution should be restandardised against fresh air after each series of determinations. This method of standardisation is advocated instead of the titration method. The following table indicates the propor- tion of carbon dioxide per 10,000 corresponding to any given number of strokes, and is based upon parallel determinations with Pettenkofer’s method and that of the authors’ : Strokes of Pump.15 14 13 12 11 10 9 8 104 98 84 Pts. CO, per 10,000 Air. 3.6 4.0 4.5 5.0 5.6 5.9 6-3 6.7 7.2 7.7 8.2 Strokes of Pump. Pts. CO, per 10,000 Air. 8.7 9.3 10.1 10.9 11.7 12.7 13.8 15-0 16.4 18.0 19 -8 A. R. T. The Active Substance in Chlorates. H. Klopstock. (Chem. Zeit., 1909,33, 21.)-An investigation, suggested by Gartenmeister’s paper (Chem. Zeit., 1907, 31, 174), of the chlorate made at the Aussig works showed that the chlorate obtained as a by-product in the electrolysis of potassium chloride liquors was rich in so-called active chlorine, By recry stallisation and concentration of the crude product, the concentration of active substance was raised to 30 per cent., calculated as potassium chlorite. The silver salt was obtained by precipitation with silver nitrate, and the potassium salt by decomposition of this precipitate with potassium chloride.The physical properties and results of analysis of these salts showed that they were notTHE ANALYSTo 237 chlorites, and, on the addition of ferrous sulphate and sulphuric acid to a solution of the potassium salt, a reddish-yellow coloration and a smell of bromine were produced. The presence of bromine was then confirmed. I n this case, therefore, the active substance was potassium bromate, and not chlorite or an unknown compound containing oxygen and chlorine. Possibly other chlorates, which on the application of Gartenmeister’s test appear to contain active chlorine, owe their behaviour to the presence of bromate (cf.ANALYST, 1909, 69). 0. E. M. Accuracy in Sampling Coal. E. G. Bailey. (J. Ind. and Eng. Chem., 1909, 1, 161-178.)-1n the present methods of sampling coal, errors of 3 to 5 per cent. in the amount of ash are common, and errors of 15 to 30 per cent. not in- frequent. The exact method of sampling should therefore be specified in the sale of coal on analysis. When any given method is employed, the error may be calculated from the laws of probability, and the accuracy of different methods may be com- pared from the calculated probable errors. The chief source of error is the size and amount of pyrites, slate, bone, and other impurities, in proportion to the weight of the sample. This ratio is termed the (‘ size-weight ” percentage, and the author’s analyses of 193 samples of the same coal show that the larger the ‘( size-weight ” percentage, the greater the error in the amount of ash.Experimental divisions of samples containing marked pieces of coal showed that the variation in the number of pieces in each portion followed the laws of probability. An empirical formuIa con- structed from these results showed that the error in the division of a sample depended upon the amount of ash from slate, etc., and on the ‘‘ size-weight ” percentage. In order that the possible error should be less than 1 per cent., the ( ( size-weight ” per- centage should be less than 0-024 per cent. if only one sample is taken, or less than 0.33 per cent. if ten samples are taken. I t is suggested that a good method would be to mix several original samples after being quartered down to a small size, and thus to obtain a final sample for powdering and analysis.The following table gives data that will be of use in sampling coal under various conditions. I t is based upon a size-weight ” percentage of 0.01, and coal containing 5 per cent. of ash from slate and impurities : A. Size of Slate contained in Coal and Amount of Original Sample required to insure the Error o j Sampling being less than 1 per Cent. of Ash. Size of Slate. Inches. 4 3 2 2 Weight of Largest Piece of Slate. Lb. 6.7 2.5 0.75 0.38 0.24 0.12 0-046 0.018 Original Sample should weigh- Lb. 39,000 12,500 3,800 1,900 1,200 600 230 90238 THE ANALYST. B. Size to which Slate and Coal should be broken before quarteriiag or dividing Samples of Various Weights.Weight of Sample to be divided. Lb. 7,500 3,800 1,200 460 180 40 5 4 .I.. Should be broken to- Inches. 2 1 18 a 8 2-mesh C . Limit beyond which Sample should not be divided when crushed to Diferent Sizes iia the Laboratory. Size of Coal Mesh. 2 4 8 10 20 Should not be divided to less than- Grams. 8,300 1,100 Should be pulverised to pass through at least a 60-mesh sieve. C. A. M. Estimation of Sulphur in Coal and Coke. M. Holliger. (Zeit. anyew. Chem., 1909, 22, 436-449,493-497.)-The author has compared the usual methods for the estimation of sulphur in coal and coke, using twelve samples ranging from lignite to anthracite and coke, and containing up to 4-84 per cent. of sulphur. The most accurate results are given by a modified Sauer method. The coal is burnt in a boat in a current of oxygen, the boat being placed in a tube provided with a constriction beyond the boat.In this constricted part are placed pieces of platinum wire, which are heated to redness before the coal is heated ; the gases produced are passed through absorption bulbs containing bromine water or hydrogen peroxide solution. The ash left in the boat is fused with sodium carbonate, and its sulphur content estimated. The method is reliable both for total and for volatile sulphur, but is too long for technical use. Eschka’s method generally yields good results, but if more than 2 per cent. of sulphur be present, or if the sample be very rich in ash, the results may be low (up to 0.2 per cent.). Hundeshagen’s method, in which potassium carbonate is substituted for the sodium carbonate of the Eschka mixture, yields results practically identical with those given by Eschka’s method.Brunck’s cobalt oxide method, as originally described, may lead to low results, up to 0.07 per cent. of sulphur being volatilised, and up to about 0.2 per cent. being left with the residue insoluble in water. By effecting the oxidation in the tube described under Sauer’s method, and extracting the residue in the boat with hydrochloric acid instead of with water, results are obtained practically identical with those given by Sauer’s method,THE ANALYST. 239 Combustion in the calorimetric bomb gives accurate results if the sample be not too rich in ash ; for coals of low calorific value, addition of naphthalene, etc., is necessary.Oxidation with sodium peroxide gives poor results if the sulphate formed is estimated gravimetricdly, on account of the large amounts of salts present. Better results are obtained if the sulphate is estimated volumetrically with benzidine or barium chromate, Volumetric methods may also be applied with advantage to all the other methods mentioned above, except to the modified Brunck method. I t may be carried out, as above, by Sauer's method. Dennstedt's lead peroxide method is not to be recommended, on account of the small quantity (0.3 gram) of coal used. Pfeiffer's method is not as reliable as Sauer's. In this method the sample is placed in an asbestos capsule in the centre of a large flask into which oxygen is passed. The sample is ignited electrically or by a burning thread, and the gases produced absorbed in a, solution of sodium hydroxide or sodium peroxide placed in the flask.The estimation of the volatile sulphur is generally of little value. A. G. L. Rapid Electro-Analysis with Stationary Electrodes. J. T. Stoddart. (J. Amer. Chem. SOC., 1909, 31, 385-390.)-1t is shown that by using stationary platinum gauze cathodes and concentric internally placed foil anodes, or mercury cathodes and stationary wire anodes, cadmium, copper, nickel, silver, and zinc (and probably other metals), can be deposited as quickly as when using rotating electrodes. The current densities used were about 10 to 15 ampdres, except when silver was deposited on a gauze cathode ; in this case the current density should not be more than 2.5 to 4 amphres.Generally, 0.5 gram metal could be deposited in twenty minutes or less. A. G. L. Method of Preparing Standard Hydrochloric Acid Solutions. G. A. Hulett and W. D. Bonner. ( J . Amer. Chem. SOC., 1909, 31, 390-393.)-The authors show that a constant boiling-point hydrochloric acid is readily obtained from ordinary hydrochloric acid by distilling off about three-fourths of the liquid taken, and then collecting the following distillate. The boiling-point is 108.54" C. at 763 mm. pressure. The strength at 760 mm. pressure is 20,242 per cent. of hydrogen chloride, the density being 1.09615 at 25" C. Between 770 and 730 mm., a decrease of the barometric pressure of 10 mm. produces an increase of 0.024 per cent. of hydrogen chloride. A. G. L. A New Reaction for Iron in the Ferrous State.A. Richaud and Bidot. ( J . Pharm. Chim., 1909, 29, 230-234.)-0n adding, to a solution containing the slightest trace of a ferrous salt, several drops of the phosphotungstic reagent used for the detection of peptones in urine, and rendering the mixture distinctly alkaline with sodium hydroxide, a bright blue coloration is obtained resembling that of Fehling's solution. This coloration is not destroyed by an excess of alkali, but disappears when the liquid is acidified. The reaction is extremely sensitive, and is obtained, e.g., with 1 drop of urine diluted with 5 C.C. of water. I t is not given by240 THE ANALYST, ferric salts. 5 C.C. of hydrochloric acid in 250 C.C. of water. The reagent consists of 25 grams of sodium phosphotungstate and C. A.M. Peroxide Method for the Estimation of Lead. W. S. Medell. (Eng. and Min. J., 1909, 87, 262; Chem. Zeit. Rep., 1909, 33, 133-134.)-0*5 gram of ore is boiled down to fuming with 10 C.C. of dilute (1 : 1) sulphuric acid and 5 C.C. of aqua regia. If manganese is present, a little sodium sulphite is added to the residue, which in any case is diluted to 50 C.C. with water, boiled, and cooled. The residue is filtered off, washed with dilute sulphuric acid, and dissolved by treating with 10 C.C. of hot 10 per cent. sodium hydroxide solution and 20 C.C. of water. The filter-paper is treated with another 100 C.C. of hot water ; the whole liquid is heated to boiling, cooled to 95" C., and mixed with 15 to 35 C.C. of a saturated solution of bromine in a 5 per cent.solution of potassium bromide. The whole is boiled for five minutes, when bromine should still be present in excess. The precipitated lead peroxide is filtered off and washed. Filter-paper and precipitate are then treated with 250 C.C. of cold water and 5 C.C. of phosphoric acid, followed by a known quantity of a standard solution of ammonium ferrous sulphate (containing 18.958 grams of the salt per litre) in excess. The titration is then finished as usual with standard potassium permanganate solution. The results obtained agree well with those obtained gravimetrically and by the molybdate method ; the presence of bismuth is without effect. A. G. L. Technical Analysis of Magnesite : Estimation of Small Quantities of Lime in Presence of Large Quantities of Magnesia.F. Hundeshagen. (Zeit. ofeiztl. Chem., 1909, 15, 85-93.)-To avoid the errors incidental to the separation of small quantities of lime as oxalate from large amounts of magnesia, the following procedure, in which the lime is first separated as sulphate, is recom- mended: One gram of the sample is boiled for ten to fifteen minutes with 80 C.C. of 5 per cent. hydrochloric acid. The solution is filtered from the insoluble residue, and evaporated to dryness on a water-bath. The residue is treated with 30 C.C. of warm water and 4 grams of crystallised sodium sulphate, and the solution mixed with 40 C.C. of 90 per cent. alcohol. After standing for at least four hours at 17.5 to 20' C.-at a lower temperature magnesium sulphate would crystallise out- the calcium sulphate is filtered off, washed with 50 per cent.alcohol, and dissolved in hot dilute hydrochloric acid. The solution is filtered from any silica, the small quantity of iron and alumina usually present removed with ammonia, and the lime precipitated as oxalate, and treated as usual. Magnesia is conveniently estimated as phosphate together with lime in another portion (0.5 gram) dissolved as above, and freed from iron and alumina by double precipitation. Or else magnesia and lime are estimated together volumetrically, by boiling the sample with an excess of sulphuric acid, and titrating back. Moisture is estimated by drying at 100" C., combined water by heating to 300- 350° C., and carbon dioxide by heating to a red heat. If organic matter or chlorine is present, carbon dioxide must be estimated directly. The loss on ignition should be estimated both before and after fine grinding, From these data the quantityTHE ANALYST.241 of magnesia actually present as free oxide is calculated. This is important, a8 neither magnesium carbonate, hydrate, nor silicate react with the chloride to form Sore1 cement. A. G. L. Estimation of Mercury in Solutions containing Iodides. H. Wegelins and S. Kilpi. (Xeit. Anorg. Chem., 1909, 61, 413-416.)-To obtain correct results in estimating mercury as sulphide in solutions containing potassium iodide, the iodide should first be removed by warming the solution gently for thirty minutes with an excess of freshly precipitated silver chloride. The solution is allowed to cool, filtered, and mercury precipitated by hydrogen sulphide after acidifying with hydrochloric acid.The results so obtained are accurate to within 0.2 per cent. A. G. L. The Colorimetric Estimation of Nitrates in Soil Solutions containing Organic Matter. W. A. Syme. ( J . Ind. and .Eng. Chem., 1909, 1, 188-189.)- The presence of organic matter in a soil solution may interfere with the colorimetric estimation of nitrates by means of phenoldisulphonic acid and ammonia. In some cases the solution is too dark to be readily decolorised with animal charcoal; in others the organic matter reduces the nitrates present, or reacts with the strong acid to form coloured compounds that cannot be matched against pure nitrate solutions. The following method of removing the organic matter has proved successful in all such cases: About 50 C.C.of the solution are heated to 60-70" C., and treated with 1 C.C. of dilute sulphuric acid (1 : 5), followed by an excess of potassium permanganate solution (5 to 10 grams per litre), which is added from a burette. The liquid is heated for fifteen minutes on the water-bath, more permanganate being added from time to time, if required, and is then filtered from the brown precipitate. The filtrate is rendered slightly alkaline with sodium carbonate and evaporated to dryness on the water-bath, and the residue taken up with water, and filtered. The filtrate is made up to 50 c.c., and the nitrates present estimated colorimetrically in the usual way. Test experiments have proved that no nitrate is formed by this treatment, but any nitrites originally present will be oxidised to nitrates. C.A. M. Method for Estimating Nitrites and Nitrates in Mixtures and in the Presence of Organic Substances. T. Zeller. (Landw. Verszdchsst., 1909, 70,145 ; through Chem. Zeit. Rep., 1909, 33, 121.)-The nitrite solution under examination is boiled with a known quantity of ammonium chloride, and the excess of ammonium chloride is then estimated by distillation with magnesia. Experimental proof is given that the method is accurate, and that the presence of nitrates and organic substances does not influence the results obtained. The details of the method for the estimation of both nitrites and nitrates are as follows : A suitable volume of the solution is placed in a 100 C.C. flask, and a known excess of standardised ammonium chloride solution is added; the mixture is boiled for two minutes, cooled, and diluted to the mark with water.Forty C.C. of this solution are then distilled with magnesia in the usual way, and the difference between the quantity of ammonia thus242 THE ANALYST. found and that added originally is a measure of the nitrite present. A further 40 C.C. of the solution are acidified with sulphuric acid, and the nitrate is reduced with metallic iron ; the solution is then distilled after the addition of sodium hydroxide, and the quantity of ammonia found represents that formed by the reduction of the nitrate together with that contained in the excess of ammonium chloride added. The difference is calculated into nitric nitrogen.A portion of the original solution should be distilled with magnesia, and the results obtained as above corrected for any ammonia found to be present. w. P. s. Detection of White Phosphorus in the Igniting Composition of Lueifer Matches. T. E. Thorpe. (J. Chem. SOC., 1909, 95, 440-441.)-The results obtained by the Mitscherlich test are sometimes misleading, since phosphorus pentasulphide may give a luminous glow under some circumstances, and this substance is a frequent constituent of the igniting composition of matches. The best method ie stated to be that of cautiously heating the dried composition until the phosphorus is volatilised as a characteristic crystalline sublimate, and is conducted as follows : A few grams of the composition, or, in the case of finished matches, the heads cut from about 200 of the splints, are placed over strong sulphuric acid in a desiccator filled with carbon dioxide, at the ordinary temperature, until thoroughly dry.The dried material is then transferred to a bulb of 25 C.C. capacity blown on the end of a tube 15 mm. in diameter and 20 cm. long. Such a bulb holds 300 to 400 match-heads. The apparatus is filled with carbon dioxide, exhausted by means of a Fleuss or Gaede pump as completely as possible, and the end sealed off. The bulb is then gently heated at from 40" to 60" for two hours, when the phos2horus will, if present, be volatilised and condensed in the cold upper part of the tube as a lustrous, transparent, highly refractive sublimate of octahedral or dodecahedra1 crystals, which increase in size after a few days, and preserve their lustre and transparency if protected from light. A very small admixture of white phosphorus can be'detected by this method, and phosphorus pentasulphide gives no sublimate under the conditions described. A.R. T. The Hydration of Preeipitates. S. U. Pickering. ( J . Chem. SOC., 1909, 95, 123-128.)-Finely divided solids, such as recently formed precipitates, were found to emulsify oils, and by suitable adjustment of the proportions of precipitate and oil an emulsion can be obtained which is of the same average density as the liquid. By determining this density (S), and ascertaining the volume and weight of the oil (V' and W'), and the volume and weight of the precipitate after drying (V and W), the volume and weight of the water (v and w ) combined with it in the freshly precipitated condition can be deduced, for W + w + W' = S (V + v +V'), and substituting sw for w (s being the specific gravity of the combined water), we get : w (1 - Ss) = S (V + V ) - (W + W').The equation can be solved by getting two sets of determinations in two liquids of different specific gravities. The precipitate employed was the basic sulphate of copper precipitated by lime-water, and the specific gravity of the liquid in which the precipitate took place was varied by the addition of sodium sulphate. Thus, copper sulphate solution was mixed with sodium sulphate solutionTHE ANALYST, 243 in the proportion of lOCuS0, : 30Na,S04, and a half-saturated solution of lime-water added to alkalinity.The unwashed precipitate was dried over caustic soda, and found to contain 11.746 per cent. H20 ; its specific gravity at 15" C . was 2.699664. This was used in its fresh state to mix with sodium sulphate and paraffin oil in varying proportions, and determinations were then made of V', W', and S, from which w was found to be (mean) 0.335, for 0*81789 gram of dry precipitate ; that is to say, the water in the freshly formed precipitate = 40.4 per cent., and the composition of the substance used = 10 CuO, SO ,,CaS04,Na,S0,,42H20, the different observations giving values for H,O varying from 33 to 59 molecules. From the weight of water in the precipitates, its mean specific gravity is found to be 0.904, which is remarkably near to that of ice (0-916), an evidence that the water of hydration of the amorphous precipitate is present in the solid form, as it is known to be in the majority of hydrated cry st alline subs t ances.A. R. T. Gravimetric and Iodometric Estimation of Silver as Chromate. F. A. Gooch and R. S. Bosworth. (Zeit. anorg. Chem., 1909, 62, 69-73, 74-76.)-Silver is completely precipitated from nitrate solution by adding an excess of potassium chromate solution, and heating the whole to boiling. As the precipitate so obtained is difficult to filter, it is best to dissolve it by adding an excess of ammonia to the liquid, and then to reprecipitate the silver chromate by boiling down to a volume of 10 to 15 C.C. The precipitate so obtained is filtered off on asbestos, washed first with a dilute solution of potassium chromate, then with water, dried, and weighed. The results obtained are accurate to a few tenths of a milligram.The presence of nitric acid is without influence, provided that enough chromate is added to prevent the formation of free chromic acid (ANALYST, 1908, 33, 371). The precipitate of silver chromate isolated as above may also be dissolved in a, small quantity of strong potassium iodide solution ; this solution is then diluted, acidified with sulphuric acid, and the liberated iodine titrated. Or else precipitation of the silver is effected by means of a known quantity of a standard solution of potassium chromate, and the excess of the latter is estimated iodometrically in the filtrate. Both methods give accurate results. A. G. L. Constitution of Blast-Furnace Slags.M. Theusner. (Metallurgie, 1908, 5, 657-667 ; J. Chem. SOC., 1909, 96, 240.)-Finely powdered slags containing 25 to 31 per cent. SiO,, 14 to 18 per cent. A120,, and 43 to 51 per cent. CaO, were extracted with (1) citric acid, (2) ammonium citmte, and (3) ammonium chloride solutions. The basicity of the slags depends upon the ratio of lime to silica, and is practically independent of the proportion of alumina. From the more basic slags, solvents at first extract lime, the ratio of A1,0, : SiO, in the residue remaining constant. Less basic slags are less attacked, the residue containing more lime than the residue from the originally more basic slags. Acid slags show microscopically much melilite, which is absent from the basic slags. An artificial melilite acts towards solvents just as an acid slag.The attack by solvents on artificial mixtures was found to be greatest when the ratio SiO, : A1,0, is highest. Water attacks slags far less readily than salt solutions:244 THE ANALYST. lime is chiefly dissolved, together with small quantities of silica and alumina, the two last-named being taken up in a colloidal form. A. R. T. Volumetric Estimation of Thallium. W. J. Muller. (Chem. Zeit., 1909, 33, 297-298.)-Thallous chloride (0.1 to 0.5 gram) is dissolved in 200 to 300 C.C. of boiling water. The solution is cooled to 65" C., 15 C.C. of concentrated hydrochloric acid are added, and the titration effected by adding standard potassium permanganate solution drop by drop. From the values so obtained 0.4 per cent.of thallium should be deducted; they will then lie within f0.45 (generally within t0.2) per cent. of the theoretical. As a check on the results, the excess of permaaganate is destroyed by boiling the liquid, a portion of which is then mixed with a known quantity of standard sodium thiosulphate solution in excess of that required to reduce the thallium ; 25 C.C. of a 1 per cent. solution of potassium iodide are added gradually with stirring, and the titration is completed with a standard solution of iodine and starch. The values so obtained should be increased by 0.74 per cent, of the thallium found; they will then be within kO.4 per cent. of the truth. A. G. L. The Volumetric Estimation of Thioeyanic Acid by Potassium Perman- ganate. (Chem. Zeit., 1909, 33, 348.)-The authors examined Volhard's statement (Lieb.Aim., 1878, 190, 160) that thiocyanic acid is quantitatively oxidised to hydrogen cyanide and sulphuric acid by potassium permanganate. Working in both acid and alkaline solutions, they always obtained low results, the quantity of sulphuric acid formed being about 6 and 3 per cent. respectively below the calculated amount, although oxidation with bromine gave the theoretical values. They attribute their low results either to the volatility of thiocyanic acid, or to the formation of stable unknown organic compounds of sulphur. The good results obtained by Parr (ANALYST, 1901, 26, 49) in the oxidation of cuprous thiocyanate are ascribed to a compensation of errors. H. Grossmann and L. Holter. A. G. L. The Separation of Tin and Antimony.L. W. McCay. ( J . Amer. Chem. SOL, 1909, 31, 373-381.)--From solutions of antimonious fluoride containing free hydrofluoric acid, hydrogen sulphide precipitates the antimony almost completely, especially if sodium acetate be added, when only about 0*0004 gram of antimony remains in 1 litre of moderately acid solution. Under similar conditions, solutions of stannous fluoride are partly, and of arsenious fluoride almost completely, pre- cipitated. Antimonic and stannic fluorides are not precipitated at all by hydrogen sulphide, and arsenic fluoride only after some time. To separate antimony and tin quantitatively, the sulphides obtained as usual are dissolved in strong hydrochloric acid. Solution is completed, if necessary, by a second treatment with hydrochloric acid after the separated sulphur has been removed by means of carbon bisulphide.Two grams of tartaric acid dissolved in a little water are added to the chloride solution, which is then filtered into a large platinum dish, neutralised with sodium hydroxide, and acidified with 5 C.C. of 48 per cent. hydrofluoric acid. Ten gremR of sodium acetate are added, the solution is diluted to 300 c.c., and antimony sulphide precipitated by passing in a current of hydrogen sulphide for one hour. The pre-THE ANALYST. 245 cipitate is filtered off, washed with water containing ammonium acetate and acetic acid, and the weight of Sb,S, determined as usual. The filtrate is evaporated on a water-bath, after adding 20 C.C. of sulphuric acid, the residue being stirred until all hydrogen fluoride has been expelled.The residue is then dissolved in water, the tin precipitated as sulphide, and converted to oxide as usual. The maximurn error on each of the metals is about fO-6 per cent. Apparently equally good results can be obtained by merely adding 5 C.C. of hydrofluoric acid to a chloride solution of the two metals containing a moderate amount of free hydrochloric acid. A. G. L. The Speed of Oxidation, by Air, of Uranous Solutions, with a Note on the Volumetric Determination of Uranium. H. N. McCoy and H. H. Bunzel. (J. Amer. Chem. Soc., 1909, 31, 367-373.)-The authors show that the speed of oxidation in air of uranium solutions, reduced to the uranous condition by zinc and sulphuric acid, is much greater than that of similar ferrous solutions, being at the rate of 0.3 per cent.per minute at 25" C. for a solution 1.5 normal with respect to sulphuric acid. The rate of oxidation is inversely proportional to the amount of hydrogen ions present-Le., it is decreased by increasing the concentration of the acid; addition of zinc sulphate only decreases it slightly. Reduction and titration should not be carried out in an inert atmosphere, as some of the uranium is always reduced to the trivalent state, and is only re-oxidised to the tetravalent condition by atmospheric oxygen, this oxidation taking place very rapidly. The authors recommend the following procedure : A solution containing about 0.3 gram of uranium (as uranyl sulphate), .dissolved in 105 C.C. of wator and 20 C.C.of sulphuric acid, is boiled vigorously for fifteen minutes with 100 grams of stick zinc (previously rendered active by treatment with an acid copper sulphate solution). The liquid is filtered into a porcelain dish, the zinc being washed with dilute (1 : 10) sulphuric acid, so that the final volume is about 300 C.C. The solution is then titrated with FG potassium permanganate solution. The error by this method is within 1 per cent. on the uranium. A. G. L. Estimation of Vanadic and Arsenic Acids, or of Vanadic and Antimonic Acids in Presence of Each Other. G. Edgar. (Zeit. anorg. Chent., 1909, 62, 77-80.)-1n one portion of the solution vanadic acid only is reduced (to the tetroxide, V,O,) by boiling with tartaric or oxalic acid; in another portion of the solution both vanadic and arsenic, or vanadic and antimonic acids are reduced by heating for one hour in a closed bottle at 100' C., with a solution of sulphur dioxide acidulated with sulphuric acid, the excess of sulphur dioxide being then removed by boiling the liquid in a stream of carbon dioxide. Both portions are titrated with a standard solution of iodine after adding an excess of potassium bicarbonate. The results obtained are accurate for both vanadium and arsenic, or vanadium and antimony. A. G. L. Colour Reaction for Zinc Salts. A. del Campo Cerdan. (Rev. Real. Acnd. Ciencias, 1908, 7, 224-231; Chem. Zeit. Rep., 1909, 33, 133.)-Carrobbio's test for resorcinol (ANALYST, 1907, 32, Sl), which consists in adding an ethereal solution of resorcinol to a slightly ammoniacal solution of a zinc salt, constitutes a delicate test for zinc, the blue colour produced being recognisable after one hour's standing with246 THE ANALYSTn a dilution of 5 mgms. of zinc per litre, if a comparison test is madeon a liquid free from zinc. I n the presence of copper, which produces a black precipitate, potassium cyanide may be first added in quantity just sufficient to decolorise the blue ammoniacsl copper solution, but an excess of potassium cyanide must be carefully avoided. Or, hydrochloric acid is added to the mixture of the reagent with the zinc salt, the red precipitate produced dissolved in amyl alcohol, and this solution shaken with aqueous ammonia, when the blue colour is produced. Or else, the copper is exactly reduced in a weak hydrochloric acid solution, the liquid is poured into aqueous ammonia covered with a layer o€ paraffin to prevent reoxidation, and a solution of resorcinol in chloroform is added, when the blue colour is obtained. Cadmium gives a green colour with the reagent. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400235

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

246 THE ANALYSTn APPARATUS, ETC. A Heating Device for rapidly obtaining Constant Temperatures for Refractometers and Polarisa- tion Apparatus. von Heygen- dorff. (Chem. Zeit., 1909, 33, 244-245.) - This consists of a vessel, c, which holds about a litre, and is provided with an inner movable outlet tube, b, to regulate the pressure and to allow the excess of water to escape through f. At the bottom of the vessel is fixed a heating spiral, d, e , preferably covered with wire- gauze and constructed in the form of the flame. The outlet-tube of this is made to dip at i, to retain any water condensed on the spiral. The water, heated to the required temperature in the spiral, passes through g into the refractometer. The inner tube, b, is kept in position by means of indiarubber tubing, as shown in figure 2, and by altering its position the rate at which the water passes through the spiral is controlled, and the temperature maintained at the desired point.C. A. M. New Method for Determining Melting-Points. S. W. Bunker. (Pham, J., 1909, 82, 324.)-Difficulties are sometimes experienced in attempting to fillTHE ANALYST, 247 the generally employed capillary-tubes for this determination, owing either to the lightness of the substance preventing its being readily shaken into the tube, or to the material being difficult to powder, such substances as camphor causing clogging ” of the tube. The apparatus devised by the author overcomes these inconveniences ; it consists of two brass rings, one screwing into the other, and to one ring a screw is attached above and below, by means of which rubber bands or other device attach the apparatus to the thermometer.Inside the larger brass ring a rubber or leather washer is first placed, then a 2-inch microscope cover-glass, which is separated from another similar cover-glass by means of a %-inch thin circular piece of platinum foil having a hole in its centre, in which the material is placed. Above the second cover- glass is another washer, and the smaller brass ring is then screwed into position inside the larger ring. The thickness of the layer of material is practically uniform, and equal to the thickness of the platinum disc. A. R. T. GOVERNMENT REPORT. Royal Commission on Tuberculosis (Human and Bovine). Third Interim Report. WYMAN AND SONS, Fetter Lane, E.C. 1909.Pp. 38. Price 4d. The Report describes experiments made with the milk and faeces of six tuberculous cows, in which the udder presented no evidence of disease. Of these six cows, three showed clinical signs of disease, but as regards the remaining three, the only evidence of disease during life was a positive reaction with tuberculin. When guinea-pigs were inoculated intraperitoneally with 0.05 gram feces, many of them developed tuberculosis, but in the case of two of the cows no positive results were obtained. To each of forty-four guinea-pigs 1 gram of faxes was administered by the mouth, in every case with negative results. When sixteen guinea-pigs were fed continuously for a week with fmes (quantity not stated) mixed with sterilised milk, one of the sixteen became tuberculous.Young swine fed with 800 grams of faxes daily for a week became tuberculous when the faeces were those of the clinically tuberculous cows, but the faeces of the three animals in better condition failed to transmit the disease in seven experiments out of eight. I n a further series of experiments, guinea- pigs were inoculated with milk. That from the less badly diseased cows gave negative results, but that from the three animals showing clinical signs of disease caused tuberculosis in one out of fifty-six, nine out of thirty-five, and twenty-one out of twenty-one successful experiments-that is to say, experiments in which the guinea-pig survived a sufficient length of time to develop the disease. Post-mortem examination showed that the cow whose milk caused tuberculosis in every case when inoculated intraperitoneally had an unsuspected tuberculous lesion of the udder.Feeding experiments with milk were also made, but in every case with negative results. That the faxes of cows, clinically recognisable as tuberculous, contain tubercle bacilli is thus established; that the milk of cows, free from tuberculous lesions of the udder, may contain tubercle bacilli is also shown, and the Commis- sioners are doubtless right in their opinion “that the milk of such cows must be considered dangerous for human beings,” though all the feeding experiments with248 THE ANALYST. milk described in the Report gave negative results. In view of the way the Report has been summarised and misconstrued in the daily press, it is matter for regret that the Commissioners did not see their way to make clear in the Report, what is sufficiently apparent to those who have leisure to study the details of the experi- ments given in the Appendix, that the danger, though real, is at any rate less grave than some busy publicists have been led to believe from a survey of the Report itself.The dauger involved in drinking the milk of any of these cows must have been very small indeed. That due to the faxes of diseased animals seems more serious, and it is well that attention has been called to this, but even here regard must be had to the doses given and to the percentage of negative results. Of sixty guinea-pigs fed with fEces, only one developed tuberculosis, and although six swine, out of thirteen experimented on, developed the disease, it must be recognised that 5,000 grams of bovine faeces is more than any human being is likely to swallow in a, lifetime. Prolonged feeding experiments with milk and with reasonable doses of faeces would afford a much better measure of the risks at present run by consumers of milk. If the Commissioners consider that experiment on such lines mould be too slow, they may fairly be reminded that they were appointed in 1901. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9093400246

出版商:RSC    

年代:1909

数据来源: RSC

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248 THE ANALYST. REPORTS. Influence of Food Preservatives on Digestion and Health. V. Form- aldehyde. ( U . S. Depnl-tnzent of Agriculture.)-This is the fifth report on pre- servatives issued by the Department of Agriculture, and, as before, it has been prepared by Dr. Wiley with the collaboration of able assistants. I t is a volume of over 200 pages, teeming with elaborate tables representing an enormous amouut of labour in the laboratories in which the analyses were conducted. The mode of procedure differed very little from that followed in the previous investigations, when the effects of benzoic acid and other preservatives were being considered. The one difference worthy of mention is the mode of administering the formalin. In the previous researches the preservative had been administered in capsules ; in this it was administered in milk.Unfortunately, however, the quantities given were so large-0.2 gram per diem (equivalent to 0.5 C.C. of 40 per cent. formalin)-that it imparted a disagreeable taste to the milk. The members of the “poison squad,” therefore, always knew when they were taking the drug, and the effects of their imagination could not be eliminated. A study of the tables shows t.hroughout that there is such a great variation in many of the physiological processes that the time over which the experiments extended-from November 12 to December 17-was not sufficiently long to eliminate their effect. For example, it is concluded that the use of formaldehyde tends to decrease the body-weight, yet a study of the curves shows that the variations during the fore-period, when no formaldehyde was being administered, were so considerable that no valid conclusions could be drawn from the results.Some of the men corn- menced to increase in weight from the very first, others began to lose weight; and it is curious to note that those who were losing weight before the formalin was administered continued to do so during the administration period, whilst those whoTHE ANALYST* 249 commenced by putting on weight continued to put on weight, and those whose weight varied very little during the fore-period remained of practically constant weight throughout the whole duration of the experiments. There is no marked or decided physiological effect recorded, but wherever the chemical results show a retarded or accelerated metabolism, however slight, it is regarded as showing the prejudicial effect of the drug upon health.The medical data show that, administered in the quantities given by Dr. Wiley, and diluted with SO small a quantity of milk that the drug could be tasted, it irritated the mucous membrane, and had a ‘( marked stimulative action on those organs and cells secreting the various digestive juices.” Mustard has a similar effect, but Dr. Wiley says it would be wholly illogical to conclude, from this increased excitation, that these bodies were helpful to digestion and conducive to health. Dr. Wiley believes the contrary is the fact, since his final conclusion is ‘‘ that the addition of formaldehyde to foods tends to derange metabolism, disturb the normal functions, and produce irritation and undue stimulation of the secretory activities, and therefore it is never justifiable.” I t is quite possible that formaldehyde, as administered by Dr.Wiley, does all that it is said to do in this report; and yet it may be possible that, used in reasonable quantities, suitably diluted with solid or liquid food, it would have no such effects. .Its use in many cases may be immoral, and therefore highly repre- hensible; but as yet there is no conclusive proof that, when used legitimately, it has any effect upon persons in good health. Its effect upon young children and invalids is another question not dealt with in the report. It is noteworthy that the Reference Board of Consulting Scientific Experts appointed by President Roosevelt has just issued its report on benzoic acid and benzoates, and, as the result of three completely independent series of experiments, the Board has arrived at the conclusion that benzoic acid, in the quantities used for the preservation of food, is not harmful, and that it does not impair the quality or nutritive value of the food with which it is mixed.This conclusion is diametrically opposed to that of Dr. Wiley, as expressed in the report recently reviewed in this journal (cf. ANALYST, 1908, 33, 486). J. C. THRESH. The Storage of Raw River Water Antecedent to Filtration. A. C. Houston. (Report to the MetropoZitan Water Board, 1909, 1-47.)-Systematic observations on the effect of storage ou raw river water were commenced in August, 1907, and the present report deals with the results obtained during the twelve months ending July, 1908.Tabulated results of the chemical and bacteriological analyses are appended to the report. The author concludes, from the results of the investiga- tion, that the policy of storing river water before filtration is fully justified. The strongest plea in favour of storage is based on the belief that adequately stored water is probably incapable of causing epidemic disease, as the microbes of water- borne disease perish rapidly in river water under storage (ANALYST, 1908, 33, 403), and these microbes are probably never present in raw river water in like number with the B. coli and B. typhosus employed in the experiments described. Further, the marked reduction in the number of B.coli when water is stored for sufficiently long periods affords a fair basis for inferring a still more marked reduction (if not total elimination) of the less hardy and less numerous microbes of water-borne disease.250 THE ANALYST. It is also seen from the results of the analyses that storage reduces the amount of suspended matter, the oolour, ammoniacal nitrogen, oxygen absorbed from perman- ganste, and may reduce, or alter the quality of, the albuminoid nitrogen. The hardness of the water is also usually reduced. The life of the filters is generally lengthened when the water has been stored previously. The use of stored water enables a constant check to be maintained on the safety of London’s water antecedent to and irrespective of filtration, and it renders any accidental breakdown in the filtering arrangements much less serious than might otherwise be the case.Thirty days’ storage may be considered reasonably sufficient for purposes of safety, provided that additional methods of purification be provided for use in times of flood or drought, when the river water could not be admitted to the reservoirs. As regards alternative measures to storage, the only possible process would be sterilisation, and this in the case of London water would be economically out of the question, and therefore impracticable. The author considers that most, if not all, the real or assumed disadvantages of storage disappear if the use of stored water is regarded as an elastic policy, which can be departed from on occasions when local conditions render this feasible and at the same time desirable.w. P. s. Food and Drugs Act, New South Wales. (Act No. 31, 1908, Assented to December 24, 1908.)-This Act, which comes into force on July 1, 1909, provides for securing the wholesomeness and purity of food, and fixing standards for the same ; for preventing the sale or other disposition, or the use, of articles dangerous or injurious to health; for the prevention of deception and fraud; and amends the Public Health Act, 1902. The word “food” under the Act means any article of food and drink, and includes confectionery, and any article, such as spices, flavouring substances, essences, and colouring matters, that enters into or is used in the com- position or preparation of food. (‘ Drug ” includes medicines for internal or external use, soaps, dusting powders, essences, unguents, disinfectants, germicides, anti- septics, and preservatives. The Act prohibits the sale of foods and drugs containing substances which interfere with the quality of foods and drugs or conceal inferior quality, and drugs must comply with the requirements of the British Pharmacopceia. On the recommendation of an Advisory Committee any food, drug, or appliance which is advertised shall be analysed or examined, and the Board of Health, at their discretion, may cause the report of the analysis to be published in the public Press, The Board may require certain statements, giving information or directions, to be written on a label attached to any package containing a disinfectant, germicide, or preservative.Provision is made for the entry of inspectors to any place used for the sale, storage, manufacture, etc., of foods and drugs, this right of entry extending to shops, eating-houses, licensed houses, etc. Directions for the taking of samples, appointment of analysts, and analysis are laid down. The analyst must declare in his certificate of analysis that he has followed’ the prescribed method of analysis, when such method is given, but the defence may give evidence that the prescribed method is incorrect. A copy of the result of any analysis of an article taken by an inspector may be supplied to the person from whom the sample was obtained, or to the manufacturer, on payment to the Board of a fee not exceeding 10s. 6d. ; such report may not be used for trade purposes or advertisement.251 THE ANALYST.The penalties for offending against this Act shall not exceed $20 for the first offence, $50 for the second, or $100 for any subsequent offence. Imprisonment, with or without hard labour, may be given to any person convicted of selling food so adulterated as to be injurious to health. Interference with official seals or marks, obstruction of officers, etc., is punishable by a, fine not exceeding 220. A guarantee may be used as a defence to a, prose.cution, with certain restrictions; the person giving the guarantee must be resident in New South Wales. The Advisory Committee appointed shall consist of the President of the Board of Health, a professor of chemistry, a bacteriologist, a medical practitioner, a medical officer of health, the senior analyst in the Department of Public Health, a represen- tative of the Pharmacy Board and of the Chambers of Commerce and Manufactures, and not more than three persons conversant with trade requirements. This Board shall prescribe standards, methods of analysis, prohibit the use of any specified substance in articles of food, etc., and generally attend to the carrying out of the @ * a + @ @ provisions of the Act. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9093400248

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 251 REVIEWS. TECHNICAL METHODS OF CHEMICAL ANALYSIS. Edited by G. LUNGE. English London: Gurney I n addition to these two parts, each of which is really a volume, two other volumes are in preparation. Presumably, as no indication of the issue of further tomes is given, these four volumes are in tended to cover the ground defined by the title. The two parts with which we are at present concerned include such diverse subjects as the analysis of sulphuric acid and alkali, aluminium salts, calcareous cements, sewage, soils and air. Each important subdivision has been allotted to a contributor selected as an expert in the matter in question, so that the object of the work as a whole is to present to the technical chemist a series of analytical monographs conveying the best and most highly specialised information.Edition edited by C. A. KEANE. Vol. I., Parts 1 and 2. and Jackson. Price 3 2 12s. 6d. net. Let us examine to what extent this object has been obtained. Of the care and pains which have been bestowed on collecting a vast quantity o matter there can be no doubt. That in several cases (notably in the chapter on potassium salts) in which descriptions of methods elaborated at the headquarters of the industry have been secured for publication the editor and contributor have done work unique of its sort must be gladly gdmitted. But in spite of these solid merits, the book as a whole (the part which is at present the whole) is disappointing. It shows a want of that critical faculty-nearly the same thing as a sense of proportion-which is necessary for the selection of what is of high importance from the trivial and insignificant.There is a lack of discrimination between matters of fundamental interest and those trifling and tedious modifications of accepted processes whereby every Chemikmzt proves his deplorable fecundity. Correlative with these defects are various positive errors that could scarcely have occurred had the contributor responsible for the item known his subject, not as a receptive student might, but as a, master should.252 THE ANALYST, But in spite of’these manifest defects, the book is valuable. Methods which had just become known when the chapter was written duly appear ; all sorts of out- of-the-way processes, useful as records of what has been done, and possibly providing an idea for improvement, are set down.Full and detailed description of processes which from their nature are arbitrary is not spared. As a fund of information the book has substantial merits, and for a chemiqt who can decide by his own knowledge whether a process is likely to be practicable or not is well worth adding to his collection of literary plant. BERTRAM BLOUNT. RAPID METHODS FOR THE CHEMICAL ANALYSIS OF SPECIAL STEELS, STEEL-MAKING ALLOYS, AND GRAPHITE. By CHARLES MORRIS JOHNSON, Chief Chemist to the Park Steel Works of the Crucible Steel Company of America. 1909. Pp. vi + 221. New York: J. Wiley and Sons. London: Chapman and Hall, Limited. Price 12s. 6d. net. This book is a collection of methods used by the author in the analysis of ordinary steels, special steels, and ferro-alloys.The processes are described in all the detail usually met with in American chemical literature, and contain a good deal of original and useful matter. Its chief defect is the entire absence of any systematic arrangement. Thus, the simpler ordinary determinations of carbon, phosphorus, sulphur, manganese, and silicon are described in the latter end of the book, which commences abruptly with qualitative tests for chromium, tungsten, nickel, and molybdenum. Chapter 11. describes the analysis of vanadium steel and ferro-vanadium, and here the author shows that as little as 0.1 per cent. of titanium can be detected in the presence of ten times as much vanadium by means of a modification of the peroxide test. A method is given for the exact determination of phosphorus, which the author states may be underestimated to the extent of seven-eighths of the actual amount present when the ordinary rnolybdate method is used in presence of much vanadium.Subsequent chapters deal with the analysis of titanium steel and ferro- titanium, tungsten powders, tungsten and chrome-tungsten steel, molybdenum powders, ferro-chrome, chrome ore and carbonless chrome, aluminium in steel, copper in steel and pig-iron, etc. Some of the processes are very good and useful, others are unnecessarily long and tedious-as, for instance, the method for determining copper in metallic copper (Chapter VIII., Part III.), which appears rather curiously in this book. Chapter IX., on the rapid determination of nickel in the presence of Cr, Fe, and Mn, is good.On the other hand, the ‘‘ rapid ’’ volumetric method for determining manganese by potassium ferricyanide, given in the next chapter, seems far behind the sodium bismuthate method in simplicity, elegance, and rapidity. Determination of carbon by direct conibustion in an ordinary gas furnace, a, furnace with blest, and an electric furnace, are well described, and many useful hints and details are given. The advantage of the author’s special form of absorption apparatus is, however, not clear, as the gas only bubbles through the potash once ; also, as the attached drying- tube is directed to be filled with pieces of ordinary, and not freshly fused anhydrous stick potash, whilst the last tube on the drying train contains P,O,, one does not see how constant weighings are possible.The limitations of the colour test for carbon are well described in Chapter XII., and some valuable observations on the annealing I t is essentially a practical book.THE ANALYST. 253 of steel are given in Chapter XIV. From the form assumed by the carbon or carbide when dissolving the steel in nitric acid, the author claims to be able to pronounce unfailingly the degree of annealing which the steel has undergone ; also to detect the presence of chromium. In describing the analysis of graphite and graphite crucibles, the existence of silicon carbide (up to 20 per cent.) in old pots is pointed out. Such pots have a green fracture. I n looking through the book one is struck by the large quantities of reagents sometimes directed to be used.Thus, owing to the unnecessarily large volume of liquid in which sulphur is precipitated, the addition of no less than 60 C.C. of a saturated solution of barium chloride is prescribed. Again, owing, no doubt, to the author’s practice of mixing paper pulp with his precipitates, the number of washings stated to be necessary is exceedingly large. For example, in the process of deter- mining titanium in ferro-titanium the number of washings directed to be given at various stages of the single determination exceeds 160; the author quite usually directs that a precipitate is to be washed thirty times. This is essentially a book for the steel-works chemist; but there is much information in it which will be found of value by all chemists whose practice includes the analysis of iron and steel.SQUIRE’S COMPANION TO THE BRITISH PHARMACOP~IA. J. and A. Churchill, London. The appearance of a new edition of this well-known work is of some significance, for it may be taken as indicating that a fresh edition of the British Pharmacopceia is not to be expected in the near future. Although nominally a companion to the Pharmacopceia of 1898, the volume before us contains st large mass of fresh material, and has the advantage over its predecessor of embodying much of the well-deserved criticism of the official publication which has accumulated during the last ten years. To the readers of this journal the changes and additions are of special impor- tance. For the first time the attempt is made to review the tests set forth in the foreign Pharmacopceias as well as in our own, and wherever possible to give the results of the application of those tests to authentic specimens of the articles referred to.The present volume contains 1,417 pages as against the 560 of its predecessor, the index occupying no less than 54 pages, a very large portion of the added material relating to analytical processes and results. To give some idea of the extent to which this is the case, it may be mentioned that no less than four and a half pages are entirely devoted to the testing of opium-the United States Pharmacopceia, 1880 ; the present British Pharmacopoeia process, with which it is almost identical ; the official German and United States processes, also Dott’s method for the assay of the crude opium, being fully described.In addition to this,:nearly two pages in each case is allotted to the testing of the extract and the tincture of this substance. Two pages are given to the assay of belladonna plasters, Bird’s process and that of the United States Pharmacopceia being dealt with in detail, and two pages each in addition are devoted to the testing of the liquid extract of belladonna and bella- donna plasters. A method of determination is given. L. ARCHBUTT. Pp. xlii+1417. Price 14s.254 THE ANALYST. The standards fixed by our own or by foreign Pharmacopceias find prominent mention, and at the beginning of the book is a table showing the strength of the more powerful standardised drugs and preparations, from which it is interesting to note that out of 37 preparations dealt with, the British Pharmacopceia fixes official standards for 15, while the German, French, and American Pharmacopceias fix limits for 20, 19, and 27 respectively.One of the features of the work of most value to the practising analyst is that it contains the results of the analysis of authentic specimens of all the more important drugs and preparations. The specific gravity and total solids of every official tincture and extract are to be found under the appropriate heading. A further improvement lies in the attention paid to the microscopic characters of the vegetable drugs, the diagnostic structures of each drug, and in many cases of its commoner adulterations also, being briefly noted. In addition to the more or less special work, the book is a manual in brief of general analytical chemistry in as far as it is applied to the nzateria nzedica.Five pages are devoted to “ indicators of neutrality,” inappropriately, though conveniently, included under which is starch mucilage, and in them the method of making up, the mode of employment, and the special uses of ten indicators, are clearly set forth. The preparation and uses of standard solutions, the commoner analytical processes employed for the analysis of fats and oils, are all clearly and practically treated, and although this portion of the book will appeal less to the professional analyst, it is evidence of the desire, which is conspicuous on every page, to make the work as thorough and complete as possible. All the chief features of the earlier editions are to be found in the present one, but to the Public Analyst, and to anyone concerned in the analysis of drugs, the volume before us may be considered as a new work, and, as regards the analytical side of the subject, it is safe to say that there is no single volume in the English language dealing with drugs which contains more information within its covers.Of course, no unofficial publication can rid the Public Analyst of the incubus of the British Pharmacopceia, a volume made legally binding on certain persons by an Order in Council passed years before the present Food and Drugs Acts existed, and which now has to be employed in a manner never intended by its original authors and for a purpose which could never have entered their heads.Nevertheless, this volume will go a long way towards lightening his burden by supplying him with records of very numerous analyses, by affording him facilities for comparing the British Pharmacopceia standards, where they exist, with those of other countries, and also by furnishing in many cases information as to the means officially adopted in other countries for ascertaining the strength or purity for which here no official method of assaying is prescribed. C. H. CRIBB. A SHORT HANDBOOK OF OIL ANALYSIS. By AUGUSTUS H. GILL, S.B., Ph.D. Fifth edition, revised and enlarged. 1909. Philadelphia and London : J. B. Lippincott Company. Price 7s. 6d. net. One’s first impression on reading this book is that the author is too ambitious. I n about 1.10 small pages of large type he endeavours to compress the followingTHE ANALYST.255 subjects : Part I. Physical and Chemical Tests ; Burning Oils, Lubricating Oils, Animal and Vegetable Oils; Examination of an Unknown Oil. Part TI. Derivation, Description, and Examination of certain Oils ; Petroleum Products, Oils and Fats, Drying, Semi-drying and Non-drying Oils, Marine and Terrestrial Animal Oils, Waxes and Waste Fats. Petroleum Products is dismissed in three pages, and Cotton-seed Oil in one page. Such a complex and difficult matter as the examination of oils is too large a subject to be dealt with so briefly, and that much of the matter is too superficially touched upon is very evident in reading the book. A few of the many omissions which occur are-P. 43 : (‘ Antifluorescents.” The author omits mention of nitric acid and aniline yellow (oil soluble), both of which are used.P. 49 : I n his list of ‘ ( Tests most Commonly Employed for the Identifi- cation of these (Animal and Vegetable) Oils,” the author omits refractive index, viscosity, and hexabromide test, though the last is mentioned later under the heading (‘ Linseed Oil.” P. 89 : I n the list of oils, “ Chinese wood oil ”-a most important oil-is omitted. It is quite true that the page is headed ‘‘ Lubricants,” but as oleic acid and linseed oil are included, Chinese wood oil would not be out of place. I t is referred to later in the book. Some of the i7zacczwacies are-P. 9 : The authors refer to “opaque” as a “ colour.” P. 19 : The definition of “ fire-test ” is loosely worded.‘‘ The fire-test of an oil is not the temperature at which it will give off vapours which when ignited will burn continuously, but the lowest temperature,” etc. P. 76: Identification of unsaponifiable matter. I t is here stated that the specific gravity of hydrocarbon oils is 0.855 to 0930, and that resin and tar oils would consequently be detected by the higher gravity. This is incorrect, as a fraction of Borneo oil having a gravity of 0.970 to 0.990 is used to blend with lubricating oils. P. 87. For cylinder oils, an addition of a drying oil, such as linseed, or a semi-drying oil, such as cotton-seed oil, cannot be recommended, while ‘‘ blown rape ” oil (which usually contains 4 to 10 per cent. of free fatty acid) is too acid an oil for use at high temperatures. P. 105 : The specific gravity of boiled oil and of blown oils (p. 127) can scarcely be described as ‘‘ constants,” seeing that they are most variable, and can be made to anything one pleases. On p. 87, last line, ‘ l Table X.” is a misprint for At the end of the book there is an appendix, containing twelve pages of tables and a few pages of oil specifications, and, finally, there is the index, which is some- what incomplete, and might well be enlarged. I t is only natural that the author, being (assumedly) American, should describe methods which are used in his country. In this country, however, they are useless. For instance, the chapter dealing with the Flashpoint of Burning Petroleum Oil is of no interest to English chemists, as we have our Board of Trade official apparatus and method. There is much that is useful and interesting in this book, but it is doubtful whether it will appeal to the majority of chemists in this country, who will probably prefer to consult a more detailed work, though the fact that this is the fifth edition seems to show that it has many readers in America. This is obviously inadmissible. Table XI.” L. MYDDELTON NASH.

ISSN:0003-2654    

DOI:10.1039/AN9093400251

出版商:RSC    

年代:1909

数据来源: RSC