摘要:

THE ANALYST. DECEMBER, 1904. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE monthly meeting of the Society was held on Wednesday evening, November 2, in the Chemical Society’s Rooms, Burlington House. The President (Mr. Thomas Fairley) occupied the chair. The minutes of the previous meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs. Percy Edgerton, 61, Cornhill, E.C., Analytical and Consulting Chemist, Gas Examiner to the London County Council and to the District Councils of Sunbury and Hampton; James McLeod, F.I.C., The Laboratory, Govan G-as Works, Glasgow, Senior Chemist to the Glasgow Gas Trust; George Arthur Pingstone, P.O. Box 445, Bulawayo, Analyst to the Bulawayo Municipal Council, Assayer to the Bank of Africa, Ltd., and to the African Banking Corporation, Ltd., etc.; and Arthur William Thorp, 2, Crofton Park, Yeovil, Analyst to Messrs. Aplin and Barrett, Yeovil, were read for the first time. Mr. H. S. Hammond was elected a member of the Society. The PRESIDENT said that he had to perform the sad duty of announcing that since the last meeting the deaths had occurred of two members of the Society, Mr. Alfred H. Allen and Mr. William Chattaway. Mr. Allen had been one of the founders of the Society, and had taken a very active part in its work and proceedings during the quarter of a century of its existence. He had been the Society’s President, had served almost continuously as a member of its Council, and had been an active worker on many of its committees, the Editorial Committee especially. Over and above and independently of all this, Mr. Allen’s book on “Commercial Organic Analysis ” had a world-wide reputation, and would have been quite sufficient to earn for him the highest approbation. Mr. Chattaway, at the beginning of his career, had been Mr. Allen’s assistant. He also had been an active worker on the Society’s Council and committees. The Honorary. Secretaries had been requested by the Council to write to Mrs. Allen and to Mrs. Chattaway, expressing the Society’s sorrow and sincere sympathy with them in their bereavement. The following papers were read : “The Detection and Estimation of Small Quantities of Maltose in the Presence of Dextrose,’’ by Julian L. Baker and W. D. Dick ; and ‘‘ The Use of Palladium-Hydrogen as a Reducing Agent in Quantitative Bnalysis, ” by Alfred C. Chapman. A double surface condenser was shown by Mr. Herbert E. Burgess.

ISSN:0003-2654    

DOI:10.1039/AN9042900345

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

346 THE ANALYST. ON THE USE OF PALLADIUM-HYDROGEN AS A REDUCING AGENT IN QUANTITATIVE ANALYSIS. BY ALFRED C. CHAPMAN. (Read at the Meeting, November 2, 1904.) SEEING that the chemical activity of the hydrogen ‘‘ associated with ” palladium in the so-called palladium-hydrogen was recognised by Graham more than thirty years ago, it is not a little strange that so few investigations should have been made for the purpose of ascertaining the possibility of utilizing this interesting substance in analytical processes involving reduction changes. As a source of pure hydrogen, as an absorbent in gas analysis, and occasionally as a means of obtaining hydrogen in a conveniently weighable form, palladium and palladium-hydrogen are not infrequently employed in the laboratory ; but as an analytical reducing agent the latter substance is, so far as I am aware, rarely, if ever, made use of.I n 1885 a thesis was presented to the University of Berne by Schwarzenbach and Kritschewsky dealing with this subject, and was apparently sent by the authors to Fresenius, who published an abstract of it in the Zeitschrift fur analytische Chemie (xxv., 374, 375). I have not been able to obtain access to the original communication, but the above-mentioned abstract appears to have been a full one, and shows that the authors experimented with a number of reducible substances, and found that in several cases quantitative results could be obtained. Prior to this (1871), Bottger had shown in the course of a communication to the Naturforscher Versammlung of Rostock that potassium ferricyanide could be reduced to ferrocyanide, but does not appear to have done more.At the time when the investigation-of which an account is given in this paper- was commenced I was not aware of the work which had been done by the above- mentioned authors; but as I have been unable to confirm some of their results, I have thought it well to repeat, as well as to extend, their observations. The palladium used in my experiments was the pure metal supplied by Messrs. Johnson and Matthey, and was employed in the form of foil of such thickness that a piece 2 inches square weighed about 8 grammes. A piece of thick palladium wire was welded to this for the purpose of supporting it in an electrolytic cell, and the foil was bent so as to enable it to be more readily introduced into the flask or other vessel in which the experiment had to be carried out.The palladium was in all cases charged by being made the negative electrode in an ordinary cell containing dilute sulphuric acid, the current being obtained either from the main through a suitable resistance or from accumulators. When fully charged (as evidenced by the rapid disengagement of hydrogen in the cell) the metal was washed, and at once introduced into the solution under examination, which was then boiled gently in a flask or covered beaker for the necessary time. Experiments showed that when charged electro- lytically the palladium ‘ I took up ” in all cases from 800 to 1,100 times its volume of gas, but the chemical activity of the hydrogen appeared to be more dependent on the physical condition of the metallic surface than upon the actual amount present.I t was found, for example, that after having been used for a number of times theTHE ANALYST. 347 reducing action became distinctly less marked, but could be restored by heating the metal to redness (preferably in a current of hydrogen) and recharging. IRON. For experiments with this metal a solution of pure ferric chloride was prepared, containing 0*010137 gramme Fe in 1 C.C. Ten C.C. of this solution were diluted to about 100 C.C. with distilled water, from 10 to 20 C.C. of 25 per cent. sulphuric acid added, and the mixture boiled gently with the charged palladium. After complete reduction, which usually occurred with the above quantities in from twenty to thirty minutes, the metal was removed and washed, and the iron titrated in the usual way with standard potassium bichromate solution.The following results were obtained : Found. Present. Fe ... ... ... 0.1002 gramme 0.1022 ,, 0.1002 ,, 0.1013 gramme 0.1002 ,, In the following experiments weighed quantities of iron wire (99.8 per cent. Fe) were taken, converted into ferric chloride, and reduced with the cbttrged palladium as above : Found. Taken. Fe ... ... . . . 0.1005 gramme 0,0998 gramme 0.1208 ), 0.1205 ,, 0-1084 ,, 0.1025 ,, 0.1025 ,, 0.1025 ,, The following results were obtained with solutions oE ferric sulphate (containing no chlorine) acidified with sulphuric acid, and reduced as above : Found. Taken. Fe ... ... . . . 0,0505 gramme 0-0500 gramme 0.0991 ,, 0~1000 ,, In technical analysis it happens very frequently that iron and aluminium are weighed together, either as hydroxides or phosphates, and it is in such cases a great convenience to be able to estimate the iron volumetrically, and to calculate the aluminium by difference.The following experiments were therefore made for the purpose of ascertaining whether phosphoric acid or aluminium interfered in any way with the accuracy of the palladium-reduction process : Series 1.-Ferric Phosphate dissolved in Dilute HCl. Time of reduction, about thirty minutes. Fe ... ... ... 0.0500 gramme 0.0500 gramme Found. Present. 0.0494 ,, 0*0500 ,, 0-0500 ,, 0.0500 ),348 THE ANALYST. Series 2.--E’ewic Phosphate with Aluminium Phosphate dissolved in HCI. Fe ...... ... 0.0247 gramme 0,0250 gramme Found. Present . 0.0247 ,, 0-0250 ,, From the above experiments it will be seen that ferric can be completely and readily reduced to ferrous salts by charged palladium, and it will be obvious that, as none of the products of the reducing agent remain in the solution to be titrated, the end-reaction with ferricyanide is sharply marked. It is interesting in this connec- tion to note that whilst palladium, when charged, is quite unacted upon by iron solutions, the uncharged metal dissolves readily in acid solutions of ferric chloride, the iron being at the same time reduced to the ferrous condition. I n the two following experiments known weights of pure iron were taken, dissolved in dilute hydrochloric, with the addition of a little nitric acid, evaporated twice to dryness with hydrochloric acid, and precipitated with ammonia.The ferric hydroxide was thoroughly washed to remove traces of nitrate, and dissolved in dilute hydrochloric acid. Into the pure ferric chloride solutions so obtained weighed pieces of uncharged palladium foil were introduced, and the liquids boiled until no further action occurred. The undissolved palladium was then removed, washed, dried, and weighed. The following results were obtained : Pd dissolve& Theory for Equation given Below. Fe taken. 1 ... ... ... 0.100 gramrue 0.0945 gramme 0.095 gramme The above numbers show that the reaction takes place in accordance with the 2 ... ... ... 0-210 ,, 0.2020 ,, 0*200 ,, equation : Pd + 2FeC1, = PdC1, + 2FeC1,. On the other hand, when the charged palladium was used the loss was less than 1 milligramme in seven hours.CHROMIUM. Acidified solutions of chromates were found to be completely reduced to the corresponding chromic compounds by palladium - hydrogen. In the following experiments known volumes of standard potassium bichromate solution were diluted with water, acidified with sulphuric acid, and boiled with the charged palladium in the usual way. After reduction the chromium was estimated as Cr20, : Found. Present. Cr ... . . . 0.1771 gramme 0-1768 gramme. 0.1771 ,, 0.1773. ,, 0.1769 ,, 0,1771 ,, COPPER. When a dilute acidified solution of cupric chloride was boiled for some time in contact with charged palladium the colour gradually disappeared, and on testing the solution so obtained with potassium iodide, with potassium thiocyanate, and withTHE ANALYST.349 ammonia, it was found that complete reduction to the cuprous state had occurred. When stronger cupric solutions were employed the cuprous chloride separated out in the crystalline state, the crystals being frequently of fair size, and often adhering to the surface of the palladium. This separation could, however, be prevented by adding to the copper solution before reduction a sufficient quantity of sodium chloride. Attempts were made to titrate these cuprous solutions with standard permanganate and bichromate solutions, but without success, the results being uniformly low and the end-points uncertain. I n other experiments the reduced cuprous solution was added, with proper precautions, to an excess of recently-boiled ferric chloride solution, but attempts made to titrate the ferrous salt formed were not successful. Titrations with iodide solutions in various ways also gave unsatisfactory results.To test the completeness of the reduction, the cuprous solutions, after treatment, were poured into a solution of potassium thiocyanate in excess, and the precipitated cuprous thiocyanate weighed either directly on a tared paper or after conversion into cuprous sulphide. It may be added that the precipitate was'in all cases pure white-whether the solutions were cold or warm-and that there was no sign what- ever of the formation of any of the cupric compound. The following results were obtained : Found. Taken. c u ... ... . . . 0.099 gramme 0-100 gramme 0.100 ), 0.100 ,, 0.099 ,, 0.100 ,, 0.116 ,, 0.117 ,, When the charged palladium was allowed to remain in contact with a cold aqueous solution of cupric sulphate for some hours it became coated with a deposit of metallic copper, and small patches could occasionally be observed in the experi- ments with the chloride carried out in the usual way.When uncharged palladium is heated in an acidified solution of cupric chloride, the solution gradually acquires, first, a deep olive-green, and then a reddish-brown colour, and is found to contain appreciable quantities of palladium, the cupric salt having undergone reduction at the same time. Experiments were made similar to those described above in the case of ferric chloride, the quantities of palladium dissolved by soh tions containing known weights of cupric chloride being determined. The following are the results obtained : Theory for Equation given below.Cu taken. Pd dissolved. 1 ... . . . 0.2110 gramme 0.1720 gramme 0.1767 gramme 2 ... ... 0.2025 ,, 0.1700 ,, 0.1695 ,, 3 ... ... 0.1180 ,, 0.0990 ,) 0.0985 ,, The above numbers are, therefore, closely in agreement with those required by the equatiion- 2CuC1, + Pd. = 2CuC1+ PdCl,.350 THE ANALYST. MERCURY. On heating charged palladium for some hours in an acid solution of mercuric chloride, a dull gray film formed on the surface of the metal, which blackened on the addition of ammonia, showing that slight reduction to mercurous chloride had occurred. When this film was removed by rubbing, the surface of the palladium was found to present a number of brilliant spots, indicating, apparently, that metallic mercury had been formed.Dilute acidified solutions of mercuric chloride appear to be without action on the uncharged metal. TIN. With stannic chloride very slight reduction to the stannous condition occurred. ARSENIC ACID. Even after boiling for three hours with fully-charged palladium, the arsenic acid had not undergoqe any appreciable reduction to arsenious acid, and in the cme of neither compound could arseniuretted hydrogen be detected in the evolved gas. MANGANESE. Very dilute acidified solutions of potassium permanganate were cornplotely reduced to manganous salts, but when the quantity of permanganate exceeded a few milligrammes the reduction to manganous salt was imperfect, hydrated oxide of manganese separating in the form of brown flakes or powder.POTASSIUM CHLORATE. A solution containing 1 gramme of pure recrystallized potassium chlorate per 100 C.C. was used. The following table will show the results obtaihed in six experi- ments, the time of contact with the charged palladium being one hour in each case, and a reflux condenser being attached to the reduction flask : Experiment. Condition of Solution. Chlorine taken. Chlorine found. 1 neutral ... 0.0723 gramme 0.03363 gramme 2 ... acid (2 drops 25%'H2S0,)' 0.0723 ,, 0-04525 ,, 3 ... ,, (5 C.C. 25% H,SO,) ... 0.0723 ,, 0.05971 ,, 5 ... ,, (5 drops 25 C.C. H,SO, every 15 minutes) 0.0723 ,, 0.04550 ,, 6 ... ,, (10 C.C. 25% H,SO,) 0.0723 ,, 0.06778 ,, I t will be seen that the reduction of the chlorate was not complete in any case, the best result being 94 per cent.of the theoretical. I n the case of the neutral solu- tion and of those to which very little acid was added the reaction was very imperfect, and the hydrogen from the charged palladium is therefore less effective than the nascent hydrogen obtained by employing zinc and dilute sulphuric acid or a copper- zinc couple. POTASSIUM PERCHLORATE. 4 ... ,, 9 9 , 9 ... 0-0723 ,, 0.04671 ,, Perchlorates in solution are well known to be very stable, and to undergo On boiling acidified solutions of pure potassium reduction with extreme difficulty.THE ANALYST. 351 perchlorate with charged palladium, only traces of chloride were formed even after some hours.BROMATES AND IODATES. Attempts made to reduce bromates and iodates to the corresponding halides in neutral solutions were only partially successful, and even after a treatment lasting several hours the greater part of each of these salts was found to have remained unat t ac ked. POTASSIUM NITRATE. Five C.C. of a 1 per cent. solution of pure potassium nitrate were diluted to about 100 C.C. with water, acidified with HC1, and treated with the charged palladium in the usual way. Even after boiling for two hours it was found that only about 10 per cent. of the nitrogen had been converted into ammonia, and the experiments were therefore abandoned. POTASSIUM FERRICYANIDE. A solution containing 1 gramme of the pure recrystallized salt per 100 C.C. was employed in the following experiments.Known volumes of this solution were diluted with water, made alkaline with caustic potash, and boiled in contact with the charged palladium in small flasks or covered beakers. When the reduction was complete (with the quantities mentioned below, fifteen to twenty minutes was found to be sufficient) the palladium was removed and washed, the solution strongly acidified with sulphuric acid, and titrated in the cold with standard permanganate in the usual manner : Found. Taken. K,FeC,N, ... . . . 0.2007 gramme 0.200 gramme 0.2006 ,, 0.200 ,, 0.2500 ,, 0.250 ,, 0-2500 ,, 0-250 ,, 0.2303 ,, 0.230 ,, I n carrying out this method, it is well that the ferricyanide solution should be made only slightly alkaline, and that the treatment with palladium should not be continued longer than is necessary. Occasionally a slight trace of iron oxide (or hydroxide) separates during the boiling, and as this somewhat diminishes the sharpness of the end-point in the permanganate titration, it is better to filter the reduced solutions in all cases.I have assured myself by very careful experiments that this does not in the least interfere with the accuracy of the method, provided that the above-mentioned conditions are observed. It will be seen, then, from the above numbers that ferri- cyanides can be completely and readily reduced to ferrocyanides, and as the methods at present adopted in analytical operations for effecting this reduction are com- plicated and leave much to be desired, I think the palladium-hydrogen process will be found very useful.VANADIUM. The reduction of solutions of vanadium pentoxide for the purpose of volumetric estimation by permanganate is usually effected by sulphur dioxide, the pentoxide being reduced definitely by this reagent to. the state of tetroxide. I t has long been t352 THE ANALYST. known that with zinc and dilute acid the reduction of the pentoxide proceeds approximately, but not definitely, to the dioxide, and this method is, therefore, incapable of being made use of in its simple form. Gooch and Gilbert (Amer. Joiirn. Sci., xv., 389) have recently shown that it is possible to reconvert the lower oxides so formed to the state of tetroxide by silver sulphate, but as this method is somewhat troublesome, and as in the sulphur dioxide reduction there is always a possibility of not completely expelling the excess of the gas by boiling, I was hopeful that the charged palladium might have carried the reduction of the pentoxide down to a point corresponding sharply with the formation of one of the lower oxides.Unfortunately, however, this does not appear to be the case. The results obtained show, in fact, that reduction proceeds beyond the stage of tctroxide, but that it does not stop sharply a t a point corresponding with the formation of any of the lower oxides, and, consequently, cannot be used for the purpose of volumetrically estimating vanadium. Pure recrystallized ammonium metavanadate was used in my experiments, and it was found that, when the charged palladium is introduced into hot acidified solutions of this salt, the yellow colour rapidly changes to green, and soon after becomes blue, showing that reduction to V,O, is readily effected. Unfortunately, as I have indicated above, the reaction continues slowly after this point has been reached, and renders the process useless for quantitative purposes.MOLY BDENU 31. I n these experiments specially-prepared molybdenum trioxide was employed, the purity of which was determined by (1) reduction in hydrogen at a red heat, (2) con- version into lead molybdate, and (3) reduction with zinc and hydrochloric acid. Weighed quantities of this compound were dissolved in a little caustic soda or ammonia, diluted with water, acidified, and treated with the charged palladium in the usual way. On boiling, the solution acquired a greenish colour, soon becoming greenish-brown.On titration with permanganate, it was found that only one-third of the molybdenum trioxide had apparently undergone reduction, but the palladium was coated with a brownish-black deposit (? hydrated MOO,). Other experiments made in this way having given similar results, the trioxide was dissolved in hot concentrated sulphuric acid, and the solution after dilution treated with the charged metal as before. I n this case no deposit formed on the surface of the metal, and the solution rapidly acquired a deep reddish-brown colour. On titrating this at the end of three hours with potassium permanganate, it was found that reduction had proceeded slightly beyond the stage of dioxide, the result corresponding with 0.104 gramme MOO,, as against 0.100 gramme taken.I n many other experiments conducted in a similar manner, it was found that, as in the case of vanadium, the reduction could not be carried to a definite stage, and only by chance could so good a result as that given above be obtained. In many cases the reduction proceeded to a point between the sesquioxide and dioxide, whilst in others it did not quite reach the latter stage. CERIUM. For the purpose of these experiments, pure chloride of cerium was obtained from Hydrated ceric dioxide was prepared from this Kahlbauin and carefully examined.THE ANALYST. 353 by the addition of an alkaline solution of sodium hypochlorite, and the yellow precipitate so obtained dried, after thorough washing, to a constant weight at 100" C.0.2 gramme of this compound yielded on ignition 0.1725 gramme CeO,, as against 0.1728 gramme required for the compound 2Ce0,.3H20. When weighed quantities of this hydroxide were dissolved in dilute acid, and the solution heated with the charged palladium, reduction to the cerous salt occurred ; but attempts to titrate the resulting solution with permanganate failed, owing to the slowness with which the reaction appears to proceed arid the uncertainty of the end-point. I t was thought that this difficulty might possibly be overcome by adding to the reduced solution a known excess of potassium bichromate, and then titrating back with standard ferrous- ammonium sulphate. It was found, however, that a volume of the latter solution precisely equal to that of the bichromate taken was required, showing either that the ceric oxide had not undergone any reduction, or that this oxide was itself capable of oxidizing the ferrous solution.The latter explanation was found to be the correct one, and indicated a means not only of proving the complete reduction of ceric to cerous oxide by the charged palladium, but also of volumetrically estimating cerium. This method is still under investigation, and the results will be communicated to the Society shortly, but the following numbers may be given here. A weighed quantity of the hydrated dioxide was dissolved in dilute sulphuric acid, and titrated directly with an TG solution of ferrous-ammonium sulphate : Found. Taken. 2Ce0,.3H20 . . . . . . 0.0984 gramme 0.100 gramme . I .... 0.1006 ,, 0.100 ,, The essential reaction involved may be expressed by the equation : 2Ce0, + 2FeS0, + H,SO, = Ce,O, + Fe,(SO,), + H,O. I t follows from the preceding that a solution of ferrous iron may be used for the purpose of ascertaining whether the charged palladium has completely reduced the ceric salt to the cerous state, and it was found that after treatment with the metal the ferrous solution was entirely unacted upon, and that even 1 drop of an FG iron solution constituted an excess which could easily be recognised by testing with ferricyanide. The investigation with which this paper is concerned was undertaken for the purpose of ascertaining to what extent palladium-hydrogen could be co?zvc&ntZy cmcl with advantage employed in analytical processes involving reduction changes. I have not, therefore, thought it desirable to proceed further with those substances -e.g., bromates, iodates, etc.-which are attacked with considerable difficulty, for even if complete reduction could be secured by employing a very large amount of the charged metal and heating for a very long time, the process would be too trouble- some to be of much practical use, and would present no advantage over existing methods.In those cases, however, in which reduction is readily brought about, the method is an admirable one, both in respect of simplicity and accuracy. The cost of the palladium is only a question of initial outlay, and, save in cases where a con- siderable number of reduction experiments would have to be carried out simul- taneously, need not be considered.354 THE ANALYST.The “ charging” of the metal is most readily effected by means of the main current passed through a suitable resistance, if direct, or through a transformer, if alternating. I n laboratories which do not possess an electrical installation, an accumulator constitutes a convenient and economical source of current. I t may be well to point out that only a small proportion of the total hydrogen is “ evolved ” in any of these experiments, and that, consequently, very little clxrrent suEces to recharge. Attempts were made to carry out some of the reductions under increased pressure, but the results were, as might perhaps have been foreseen, less satisfactory than those obtained in the ordinary way. I feel that I cannot conclude this paper without alluding very briefly to the bearing which the results appear to have upon the nature of ( ( palladium-hydrogen,” although such a discussion is perhaps somewhat out of place in a communication dealing with analytical processes.I t will be observed that I have throughout avoided the use of the words ( ( occluded ” and ‘‘ combined,” inasmuch as considerable differences of opinion still exist as to the nature of the substance to which we give the name “ palladium-hydrogen.” It is well known that Graham regarded i t as an alloy containing “the volatile metal hydrogenium,” and that subse- quent observers, including Dewar, and Troost, and Hautefeuille, considering it to be a compound, have assigned to it such formulz as Pd,H, and PdZ,H.More recently the subject has been very carefully examined by Mond, Ramsay, and Shields, who appear to regard the evidence they have obtained as, on the whole, opposed to the theory of chemical combination. I t is noteworthy that the question has throughout been attacked almost entirely from what may be termed the physical side, conclusions for or against the existence of a chemical compound having been based upon the results obtained in the investigation of such properties as vapour pressure of palladium-hydrogen at different temperatures, the heat of occlusion,” and h e influence of increased pressure on the quantity of hydrogen absorbed. The formula Pd,H,, on the other hand, was assigned to palladium-hydrogen because it represents fairly closely the actual composition of the fully-charged metal.The hydrogen in palladium-hydrogen may be simply occluded or condensed in the pores of the metal, or it may occur in the form of a solid solution, or it may exist in actual chemical combination, or, finally, it may be present in two or more of the above states. This is not the place to enter into a close examination of thefie views, even if I had obtained sufficient new experimental evidence to justify me in doing so ; but I may, perhaps, be permitted to say that the observations which I have made during the progress of my investigation appear to me to favour the view that the hydrogen exists at least partly in a state of chemical combination, and probably in two forms. It must, of course, be remembered that at the temperature of my experiments (approximately 100” C.) only a part of the hydrogen is ‘( evolved,” but of this conipara- tively little (often not more than 5 per cent.) is concerned in the chemical reducing changes involved. In accordance with our present views it is the atomic, or “nascent,” hydrogen alone that is capable of bringing about such changes, and a portion at least of the hydrogen must, therefore, be in this condition at the moment of separation. It is true that our knowledge of the precise nature of ‘‘ occlu~ion’’ is comparatively slight ; but it is, I think, much more probable that hydrogen whichTHE ANALYST.355 is evolved in the chemically active or atomic condition has resulted from the splitting up of a compound than that it has been formed in the process of being driven out of the pores of the metal in which it was condensed or liquefied, or while being liberated from a state of solution. I have obtained other evidence which points, I think, in the same direction, and I may possibly deal with this on another occasion.I t gives me much pleasure, in concluding, to gratefully acknowledge the capable assistance rendered to me in this work by my assistants, Mr. H. A. Thiersch and Mr. P. Whitteridge, B.Sc. DISCUSSION. The PRESIDENT (Mr. Fairleyj said that this peculiar alloy, or whatever it might be, of palladium and hydrogen had since its discovery been one of the most interesting of substances, whether from an analytical or from a purely scientific point of view. He had calculated what the apparent volume of the hydrogen in it might be, and had found that palladium absorbed, roughly speaking, about 1,000 times its volume of hydrogen, and in so doing expanded about one-tenth of its volume.Calculated from exact data, Dewar::: found that the density of the hydrogen worked out to a mean value of 0.62 as compared with water. The pressure required to produce this result would be something like 10,000 atmospheres, so that obviously there was here something very wonderful, assuming-which was a very large assumption, bearing in mind the electric theory of matter-that palladium really filled up its own space. The action of ordinary hydrogen on silver solutions has been studied by Bunsen, Russell, and others (Joz~rrc. C'hem. SOC., 1874, p. 3). Under ordinary circumstances a certain proportion of the silver present in a nitrate solution is precipitated by hydrogen previously purified by careful washing with excess of silver nitrate. But the whole of the silver cannot be so precipitated, as the reaction is a reversible one.I t was interesting, comparing this reagent with others, to note some differences in its action. The reduction of ferric salts by means of sulphites, for instance, took place with great facility in the hands of some persons, while others experienced much difficulty. The point simply was that if the excess of acid in the ferric solution was kept very minute reduction was readily obtained, whereas if there were a large excess of acid one had to go on adding sulphite for some time before the reduction was complete. Apparently, with palladium-hydrogen an excess of acid did not interfere with the reduction. I t would be interesting to extend the investigation to many of the organic colouring matters and such bodies as were readily reduced to leuco-compounds. In all probability palladium-hydrogen would prove as useful for such substances as for metallic oxides.He was not quite clear whether in the earlier experiments the palladium wag charged by first heating it to redness and then cooling it slowly in a current of hydrogen, though no doubt, apart from the question of convenience, the same results would be obtained as by the method adopted by Mr. Chapman. Mr. HERBERT E. BURGESS inquired whether Mr. Chapman had tried the action of palladium-hydrogen on any organic substance-for instance, for the reduction of .< I'YOC.Chem. SOC. 1897, p. 192.356 THE ANALYST. an aldehyde to an alcohol. A large field for research seemed to be open in this direction. Mr. HEHNER said that possibly the comparative failure which Mr. Chapman had met with in certain cases-that, for instance, of chlorates-might be turned into success if a trace of a ferrous salt were present. Some years ago, in an investigation on the subject of chlorine determination, he (Mr. Hehner) had found that chlorates were readily reduced in acid solution by ferrous compounds. If a trace of iron were present with the palladium-hydrogen, the reducing action would be continuous, for the iron would go on reducing, the resulting ferric salt being itself reduced by the palladium-hydrogen.Mr. A. J. MURPHY inquired whether, before abandoning the attempt to reduce nitrates, Mr. Chapman had made experiments with such quantities as would be present in ordinary water. I t would be interesting to know whether there was any chance of palladium-hydrogen proving a successful rival to the copper-zinc couple, because occasionally waters were met with which were rather stubborn, and required for complete reduction a much longer time than the one, two, or more hours usually regarded as sufficient. Mr. CHAPMAN, referring to the early experiment of Bunsen, of which the President had spoken, said that he also had some recollection of a statement that silver salts were reduced by hydrogen, but he should like to know (possibly someone present did) whether the experiment was made under such conditions as to preclude the possibility of any impurity in the hydrogen.He thought that for all practical purposes it might be taken that it was only the so-called “nascent ” hydrogen that possessed this particular kind of activity ; but he spoke subject to correction, as he did not remember the particulars of the experiment in question. We heartily agreed with the suggestions that had been made as to the application of this reducing agent to some of the reducible organic colouring matters. He had tried its action on acetic acid, and had found that after several hours’ boiling with fully-charged palladium a trace of alcohol was formed. He believed it had been stated that nitrobenzene could be reduced to aniline in this way, but he had not confirmed that, and, in fact, had made no experiments with organic substances except the single one with acetic acid.He was very much indebted to Mr. Hehner for his suggestion. No doubt a lirace of ferrous salt would cause the reduction to be complete in some of the other cases. He had, however, concerned himself more particularly with the action of palladium- hydrogen from the scientific point of view; and it was only in the case of those substances which were reduced easily and readily that he had considered it worth while to work out the process fully. If it proved troublesome, complicated, likely to take a long time, and especially if it necessitated the introduction of some other substance as an intermediary, he did not consider that it would possess any advantage over existing methods. In all the four cases in which he had recommended it it was an excellent process. Iron was readily reduced, there were no products from the reducing agent, the end reaction was sharp, and the whole process was simple and cleanly. In the case of chromium (in which it was, perhaps, not quite so necessary) it worked equally well. With ferricyanides-for which at present there was no simple reducing process-it worked excellently, and it also gave good results withTHE ANALYST. 357 cerium. Probably in some of the other instances conditions could be found in which complete reduction would take place, but it was, perhaps, scarcely worth while pursuing the matter further in such cases, because satisfactory processes were already available. The nitrate solution used for these experiments had been a strong one, and he had not made any experiments with natural waters. He had always found the copper-zinc couple very satisfactory for quantities up to, say, 1 grain or 2 grains of nitric acid per gallon. I t was, however, quite possible that with such small quantities of nitrates as occurred in natural waters the reduction with palladium-hydrogen might be complete. That answered Mr. Murphy’s question with regard to nitrates. For larger quantities he invariably used the Crum process.

ISSN:0003-2654    

DOI:10.1039/AN9042900346

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE ANALYST. 357 RESULTS O F EXPERIMENTS ON T H E EFFECT O F BORAX ADMINISTERED WITH FOOD. BY H. W. WILEY. THE following is an abridged account of Circular No. 15 issued by the United States Department of Agriculture and the circular is itself a digest of a much larger buIletin presented to Congress in accordalzce with an authority from that body conferred on the Secretary of Agriculture to investigate the influence upon health and digestion of various substances added to foods either as preservatives or colouring matters and to establish principles which should be a guide to their use. I t is pointed out that an important; point of distinction between modern preservatives and the long-established ones-salt sugar vinegar and wood-smoke-is that in the small amounts used they are almost without taste or odour and their presence in a food product would not be noticed by the consumer unless specifically proclaimed.In determining che plan of the investigation it was decided for well-considered reasons neither to employ artificial methods of digestion nor to experiment upon the lower animals but to employ the human organism itself. As it was impossible to insure absolute control over a number of experimentees a number of young men employed in the Civil Service were selected. These volunteered for the experiment, and were simply placed upon their honour to obey certain rules and regulations imposed on them whilst the experiments lasted. They were allowed to follow their usual vocations. Applicants who were in the habit of consuming alcohol mere excluded but the moderate use of tobacco was allowed.The hours of meals were fixed as follows Breakfast 8 a.m. luncheon 12 a.m. dinner 5.30 p.m. these being the customary meal-times of those employed in the service. The meats selected were roast beef beefsteak veal pork chicken and turkey fish and oysters; also eggs were served twice a week milk and cream fresh vegetables and fruits of the season, and others preserved by sterilization only. Soups were purchased from a large manufactory. The greatest pains were taken to secure absolute freedom from antiseptics of the whole of the food consumed. Coffee and tea were allowed i 358 THE ANALYST. moderate uniform quantities. Custards rice pudding and ice cream were given at regular times. A liberal supply of fruits was incorporated with the food-supply.The bill of fare was varied every day but recurred regularly in seven-day periods. The dining-room arrangements were made in an inexpensive manner but so contrived as to insure a neat and attractivc table. Three divisions were made of each series of observations-namely fore period preservative period and after period ; the time assigned to each of these varied somewhat and the total time of the three extended from thirty to seventy days. During the entire time of observation the rations of each member of the table were carefully weighed or measured and the excreta collected. The object of the fore period was to determine as nearly as possible the quantity of food required to maintain the body-weight at nearly a constant figure, and to determine the normal metabolism as a basis of comparison with that of the preservative period.Preceding the fore period the quantities of food freely chosen by each individual were noted so that some idea might be formed of the proper amount to be weighed or measured. If it was evident that too much food had been habitually consumed keeping the body in a plethoric state the rations were cut down somewhat in order that this condition might be removed. The quantity of the ration was therefore varied either by increase or decrease until at the end of about ten days there was no very marked daily change in weight. I t was found impracticable, however to secure an absolute constancy of body-weight since climatic conditions, slight differences in the amount of exercise and variations in the quantity of excreta, all combined to produce variations in weight (as ascertained at any given period of the day) which are more or less independent of the actual quantity of food consumed.I n order that these daily variations might be eliminated from considera-tion in the comparison of data the average weight for the fore period was taken as the initial point. The quantity of the ration having been thus determined by the observations of the fore period the preservative period was entered upon. During this time the quantity of ration previously determined was given without variation except in case of sickness or some unavoidable condition and to this ration a certain quantity of the preservative to be studied was added.Borax was selected as the first preservative to be experimented with both because it is probably the most important of the commonly used preservatives and also because it lends itself to purposes of demonstration the most readily. The pre-servative was exhibited in two forms-namely borax and boric acid - as it was thought possible that the soda entering into the former might produce some modifi-cation of the results. During the first part of the experiments here described the borax or boric acid was mixed with the butter. In later periods of the study it was deemed advisable. for reasons given hereafter to administer the preservative in capsules. Preliminary experiments had shown that there was no objection to this method though it is different from the actual method of consuming preservatives when added to foods in the ordinary way.I n the administration of the preservative small quantities were first given approximately as much as would be consumed in eating foods preserved with borax such as butter and meat. These quantities were progressively increased for the purpose of reaching if possible the limit of toleration of the preservativ THE ANALYST. 359 by each individual. For each variation of the quantity given a separate study of the digestive processes as influenced by the preservative was made. At the end of the preservative period the after period began during which practically the same quantities of food were given as in the preservative period, the preservative however being omitted. The object of this after period was to restore the individual as nearly as possible if there had been any disturbance of his physical state to the condition precedent to the beginning of the experimental period.During the entire time from the beginning of the fore period to the end of the after period the foods were weighed or measured and analysed and the excreta collected and analysed. The whole of the persons experimented on were placed under medical super-vision being visited by a medical man twice a week who submitted them to a careful physical examination symptoms of any disturbances in their physical state being inquired into. Those cases where persons were unable to continue their services during a whole period were duly noted in the details of the experimental work. Any changes in the relative number of corpuscles of the blood or in the blood-colouring matter were noted but this was not commenced at the beginning of the experiment and does not cover the whole time of the work.The body-temperature was taken daily sub lingua as also was the rate of the pulse any alteration in these being verified by a second observer in addition to the subject himself. The weights of the body were ascertained by means of a platforni scale with agate bearings and of a delicacy sufficient to register easily differences of weight of 10 grainmes when carrying a man of average weight. The subjects were weighed without clothes and it is not safe to assume that the weight of clothing remains constant. In the general discussion of the influence of weights it mas deemed advisable to take the average weight for a period of days rather than the separate weight for any one day.Aside from the usual difficulties connected with analytical practice which must always be taken into consideration there are some special points in connection with a work of this kind which must be mentioned. These difficulties are connected chiefly with the collection and analysis of the excreta. The principal object in the analysis of the excreta as is evident is to establish the relation between certain ingested elements and those which appear in the excreta. Certain forms of food are more or less completely changed in passing through the body and are oxidized and manifested as heat and energy. The fats and carbohydrates are types of food of this kind.Certain other elements in foods. while they undergo marked changes of combination during digestion assimilation and excretion appear in the excreta in practically the same quantity in which they are found in the food. Among these substances may be particularly mentioned nitrogen sulphur and phosphorus. In a state of equilibrium where the body is exercising all of its functions in a normal manner and where there is neither increase nor decrease in body-weight, the quantities of nitrogen sulphur and phosphorus which are excreted should be the same as those which are ingested in the food. This should not be construed to * 360 THE ANALYST. imply that the actual elements eaten on one day appear in the excreta of the next day. Were it practicable in experiments such as these to collect absolutely every particle of emergent nitrogen for instance the balance between the entering and departing nitrogen should be complete.In these experiments however no attempt was made to collect any of the nitrogen except that removed from the body in the urine and faxes. This of course represents nearly all of the nitrogen excreted but not quite all. The same statement may be made with reference to the sulphur and phosphorus. I t is evident however that if a relation can be established between the total amount of these substances entering the food and that leaving the body in the urine and faxes any disturbance of that relation by the addition of an abnormal con-stituent to the food such as a preservative can be easily detected.Therefore for the purposes of these investigations the fact that complete collection of these elements from the body is not secured is not a valid objection to the deductions which are made from the data. Nevertheless it should be pointed out with clearness and frankness that in the conditions in which these experiments were made there are possibilities of error which must not be overlooked. Carelessness on the part of the observer himself in the collection of the excreta a violation of the pledge in regard to the conduct of life or an error in analysis would each tend to render the results of less value. That such errors have been wholly excluded from the data submitted is not likely. On the other hand errors of this kind which may have been introduced could not have been purposely made in order to modify the final results of the investigation.Hence it is fair to assume that such errors are to a certain extent compensatory and that they do not affect seriously the conclusions based upon the data as a whole. Those who have worked in investigations of this kind however will understand the great difficulties which attend them as well as the care which has to be exercised in their conduct and will be the more ready to excuse any unavoidable error which may have crept in either in the conduct of the work or the morale of those who were subjected to the experiment. Another important factor which must be considered in the interpretation of the data which have been obtained in these experiments is the effect of regular habits of living uniform quantity of diet and general control of the appetite upon the physical well-being of the subject.I t is usually considered by physiologists and physicians that regular habits of life conduce to health and strength. This theory has been corroborated by the results of the experimental work here detailed. While it is true that in many instances during the progress of the investigation the experimentees were made temporarily ill by the quantities of the preservatives administered it is nevertheless, an interesting fact to note that at the end of the year after the final after period had been passed they appeared to be and declared themselves to be in better physical condition than when they entered upon the experimental work seven months before.This fact as has already been stated must not be neglected since it is evident that the tendency toward a good physical state and good health produced by the This is far from being the case THE ANALYST. 361 regular habits of life might counteract the unfavourable tendency of any exhibited preservative so that at the end of the observation if the results were judged only by the condition of the subject at that time they might be pronounced negative or even helpful whereas in point of fact the preservative might have produced injurious effects. Self-restraint temperance regularity of exercise regularity in hours of sleep and hours of work are believed to have favourable effects and these were manifested in a marked degree throughout the whole of the experimental work.That the personal attitude of the individual experimented upon influences to a certain degree the progress of digestion is undoubtedly true. Every physician and physiologist is familiar with the marked effect which mental states produce upon the bodily functions. Cheerful surroundings good company and in general an agreeable environment tend to promote the favourable progress of digestion; a reversal of the conditions of environment have exactly the opposite effect. The question therefore arose in connection with the experimental work as to the advisability and possibility of preventing the mental attitude from producing any effect. A careful consideration of all the conditions of the problem made it clear that it would be impossible to conduct the experiments in any way which would exclude from the knowledge of the participant the fact that preservatives were added to the food.I t was fully understood that he was employed for this purpose and the very moment that the observation began upon his daily life by weighing the food and collecting the excrete he would be aware of the fact that he was under observation, and was probably partaking of preservatives. The question also arose whether or not the preservatives should be given in capsules openly or whether they should be concealed in the food itself. Both of these methods received a thorough experimental trial. When the preservative was mixed with the food in such a way as to conceal its physical appearance a certain dislike of the food in which it was supposed to be was manifested by some of the members of the table.Those who thought the preservative was concealed in the butter were disposed to find the butter unpalatable and the same was true with those who thought it might be in the milk or the coffee. When on the other hand, the preservative was given in the capsules with the full knowledge of the subject much less disturbance was created. In fact after a day or two when the subject hecame used to the fact that he was taking a preservative it was apparent that the efYect of the mental attitude was not at all noticeable. All the foods offered were relished because they were known to contain no preservative while the preservative itself exhibited in the form of a capsule imparted no bad taste or other disagreeable effect.If an experiment of this kind were to be continued only a few days it is evident that the mental attitude of the subject would be a matter of much concern; but when from thirty to seventy days are employed in one series of observations and especially when the observations are continued for many months this effect rapidly wears away, and probably does not influence the final results in any appreciable manner. The young men were cautioned to avoid discussing the development of any symptoms which they might notice among themselves and were urged not to dwell These effects may be either favourable or unfavourable 362 THE ANALYST. upon any indications of abnormal conditions which they might experience but to keep their minds employed on their usual vocations and to avoid thinking as much as possible about the experiments which they were undergoing.I n most cases this course of procedure had its desired effect ; and from the general deportment of those upon whom the experiments were made it may be stated with a considerable degree of confidence that the mental state as a whole had very little influence upon the course and progress of digestion. The great difficulties of correctly studying the extensive data which these experiments have given and drawing therefrom the proper conclusions are fully realized. The utmost care must be exercised in these cases to remove all possible personal bias and to free one’s self in so far as possible from the weight of authorities which have been consulted. Public opinion also must not be forgotten in this respect especially when it is considered that it is almost universally believed by the great majority of people that added preservatives are always injurious and in many instances poisonous.But even when personal bias weight of authority and public opinion are eliminated from the problem it is still a most difficult one. So many elements enter into its study so many conditions difficult to control so many idiosyncrasies are to be reckoned with so many external causes influencing health are beyond control that it is difficult in many cases to decide where variations are noticed as to the exact or even the apparent cause which has produced them. The problem therefore has been attacked with a full knowledge of its dieculty and with the desire to be conservative and free from dogmatism.I t would probably be better if all the detailed data which have been secured could be printed in con-nection with this discussion so that the critical reader might be able in every instance to refer to the original figures. Enormous space however would be occupied by the data; and the fact that in most cases they would be of little use in detail has led to the decision to publish only summaries with such detail as may be necessary to point out the way in which the general data have been obtained. If as may appear later on all points of the problem have not been elucidated the failure has not arisen either from lack of desire or froin want of industry in the conduct of the experiment. It is to be attributed rather to the limitations placed upon the observers either by lack of experience or by lack of knowledge how to properly classify digest and study the data at their disposition.A serious attempt has been made to present these data in their full significance and in no case has any tampering therewith been counselled, desired or permitted. The unfortunate fact that many of the data are contradictory must be accepted without question. As the judge and the jury in the light of contradictory evidence seek to decide which is the more trustworthy so have the data herein contained been interpreted with a view if possible to give the greater weight to those which deserve the greater credit. Of interest in connection with the other purposes of this investigation is a study of the relation of the weight of food consumed to the body-weight which was made in detail during the first series of observations.This study was made of each individual article of diet and included a statement of the ratio of the weight of food, including the water consumed and the ratio of the weight of the dry matter in the food to the body-weight. During the fore period first series of observations th THE ANALYST. 363 average daily weight of the moist food including water drunk was 4.20 per cent. of the total weight of the body; during the preservative period 44.22 per cent. and for the after period 4.21 per cent. That is in about twenty-four days the average healthy young man would consume a quantity of moist food including water drunk, equal to his own weight. I t is seen by the above that the administration of the preservative caused very little variation in the weight of food consumed compared with the weight of the body.Reduced to water-free basis the quantity of food consumed in relation to the weight of the body is as follows : Per cent. Fore period . . . . 0.96 Preservation period . . . 0.99 After period . . . . . . 1.01 These data show that there is very little difference between the total quantity of dry matter in the food during the three periods. The total quantity of dry matter in the food consumed daily is in round numbers 1 per cent. of the weight of the body. For a man weighing 150 pounds therefore the quantity of dry matter daily consumed in the food is about 1.5 pounds. I t is also interesting to note that the daily ratio of the moist food including the water drunk is a little more than four times as great as that of the dry food.Similar data for the other series of observations are recorded but the further discussion of the problem is not deemed necessary. I n every series there was a marked tendency on the part of boric acid and borax to diminish slightly the weight of the body although this tendency was in some instances checked during the after periods and a portion of the loss of weight was regained. I n general however there was a tendency to continue the loss of weight during the after periods. The borax and boric acid taken into the stomach during the progress of these experiments were excreted almost entirely by the kidneys. In the first series of experiments 83.05 per cent.were thus excreted in the second series 82.85 per cent., in the third series 63-87 per cent. in the fourth series 82.96 per cent. and in the fifth series 75-17 per cent. During the course of observation 607.4 granimes of preservative were given either in the form of boric acid or the equivalent in borax, of which 468-69 grammes were excreted in the urine or 77.16 per cent. of the whole. These numbers include the data for Series III. where the quantity of the preserva-tive recovered in the urine appears to be abnormally low. I n round numbers it may be said that 80 per cent. of the boric acid and borax taken into the system in foods is excreted in the urine. I t is probable that the rest is chiefly excreted with the perspiration. A careful study of the effect of the preservative administered upon the composi-tion of the faeces shows a slight tendency to increase the amount of water therein.There is however no tendency of any marked nature even when the preservatives are given in large quantities to excite diarrhea. The administration of the pre-servative produces a slight increase in the weight of dry matter in the faeces. Only small quantities are found in the faeces 864 THE ANALYST. There is only a slight effect produced as a whole as determined by the data of experiment upon the excretion of nitrogen. The individual variations are somewhat marked showing the danger of depending too positively upon data from only one or two persons. A slight tendency is shown however on the part of the preservative to decrease the excretion of nitrogen which tendency becomes more marked after the withdrawal of the preservatives.For instance the average nitrogen balance of the four series of observation (excluding Series 11.) during the fore periods is 1.009, during the preservative periods 1.12 and during the after periods 1.74 grammes per day. Expressed as a percentage the combined data show an excretion of 94.2 per cent. of nitrogen taken in the food during the fore periods 93.6 per cent. in the preservative periods and 90-1 in the after periods. The general sumniary of all the experiments with borax and boric acid indicates the largest elimination of nitrogen in the fore periods an intermediate amount in the preservative periods and the smallest elimination in the after periods.This relation is either produced by causes other than the administration of the preservative or the effect of the pfeservative continues after its administration has ceased and even after the preservative itself has ceased to be excreted from the body. It is not impossible that such an influence may be exerted. The retarding influence of the preservative probably increases with the length of the experiment especially in those cases in which the amount of preservative administered is progressively increased. When the administration of the preservative is discontinued the elimina-tion of nitrogen is probably at the lowest point (if depressed by the preservative), and yet during the first days of the after period (at least while the preservative is still in the system) the amount of nitrogen eliminated is probably as low as on the preceding days.There may be a tendency of the preservative in the large amounts in which it is administered to increase the formation of difficultly soluble compounds of nitrogen and by that means if no other retard its elimination from the body. A study of the data relative to the influence of boric acid and borax upon the metabolism of phosphorus reveals many contradictory results. When however all the data are collected into one expression it is found that the influence of these bodies added to the food is distinctly marked on the metabolism of phosphorus and phos-phoric acid. There is a distinct tendency shown by them to increase the quantity of phosphoric acid excreted during the period of the administration of the preservative.In the combined data of Series I. III. IT. and V. the average percentage of phos-phoric acid taken in the food eliminated during the fore periods of observations is 97.3 during the preservative periods 103-1 per cent. and during the after periods 97-0 per cent. The influence of boric acid and borax upon the metabolism of fat is not very marked. There is a slight tendency shown to decrease the elimination of fat in the faxes during the administration of the preservative and a tendency to recover is shown during the after periods. The percentage of fat ingested in the food eliminated during the fore periods is 4.1 during the preservative period 4.0 per cent. and during the after periods 4.2 per cent. These data show that almost no disturbance in the metabolism of fat is caused by the administration of the preservative.The collected data of all the series (except Series 11.) show that 6.4 per cent. o TAE ANALYST. 365 the combustible matter in the food is eliminated unburned during the fore periods, 6.6 per cent. during the preservative periods and 7.0 per cent. during the after periods. These data show a slight tendency on the part of the preservative to interfere with the combustion of the food in the body and this tendency is continued in even a more marked manner during the after periods. The solids summary for all of the series (except Series 11.) shows that the average quantity of solids in the food during the fore periods is 631.5 grammes during the preservative periods 627.6 grammes and during the after periods 614.1 grammes.The average daily quantity of solids appearing in the faxes in the fore periods is 25% grammes in the preservative periods 28.6 grammes and in the after periods 28.3 grammes. The average quantity appearing in the urine during the fore periods is 64-48 grammes during the preservative periods 59-37 grammes and in the after periods 56.20 grammes. The average balance of total solids during the fore periods is 544.701 grammes during the preservative periods 539.875 grammes and during the after periods 530.123 grammes. These data show a marked tendency on the part of the preservative to increase the total solids excreted in the fteces and to decrease the total solids excreted by the urine. There is a distinct tendency manifested by the preservative to interfere with the processes of digestion and absorption.Inasmuch, however as the total quantity of solids administered in the food varied slightly in the different periods a fairer interpretation is obtained by comparing the percentages of the total solids exhibited in the food eliminated by the fzeces and urine respectively. In this comparison it is found that the total percentage of solids in the food eliminated in the fzces during the fore periods is 4.1 during the preservative periods 4.6 and duirng the after periods 4.6. The percentage of solids in the food eliminated in the urine during the fore periods is 10.2 during the preservative periods 9.5 and during the after periods 9.1. These percentages indicate also very strongly the influence exerted by the preservative mentioned above.I t must be remembered also in this connection that practically 80 per cent. oE the preservative administered is recovered in the urine increasing to that extent the total solids thus eliminated. I n spite of this however there is a marked decrease in the total solids in the urine and a marked increase in the total solids in the faeces. The combined data of the four series (excluding Series 11.) show that the percentage of nitrogen ingested in the food eliminated in the urine during the fore periods is 85.7 during the preservative periods 85.1 and during the after periods 81.1. This shows a tendency on the part of the preservative to diminish the percentage of nitrogen excreted in the urine and this tendency is continued in a very marked manner in the after periods.The data of Series IT. III. and V. show a marked tendency on the part of boric acid to increase the acidity of the urine. In no case during the administration of boric acid was an alkaline reaction observed. I n the case of the urine the marked acidity imparted to it by boric acid is continued in most cases throughout the after periods. The data of Series IV. and V. on the contrary show a marked tendency on the part of borax to diminish the acidity of the urine and in several instances this substance imparted to the urine an alkaline reaction. These facts indicate that a large part of the borax and boric acid administered is excreted unchangedin chemicd composition 366 THE ANALYST.Very little effect is produced by these preservatives upon the volume of urine, although there is a slight tendency manifest to decrease the amount. There is a slight tendency also manifested during the administration of the preservatives to decrease the total solids in the urine. I n this connection however it must be considered that the season of the year has a marked effect upon the amount of urine secreted the tendency being to secrete larger quantities in cold weather than in warm. Combining the data of Series I. III. IV. and V. for those members completing the series we find that the average daily amount of urine secreted during the fore periods per individual is 969 c.c. during the preservative periods 960 c.c. and during the after periods 952 C.C.These data show almost no effect of the preservatives on the quantity of urine secreted but there geems to be a slight tendency to decrease the amount secreted in the preservative and after periods. I n those few cases where there was normally a mere trace of albumin in the urine it is shown by the data that the general tendency of the preservative used is to increase the trace of albumin in the urine and this increase is manifested also during the after periods. Microscopical examinations of the urine were made for the following substances : Uric acid crystals ; urates ; oxalate of lime ; phosphates (a) crystalline phosphates (b) amorphous phosphates ; epithelium cells of all kinds ; leucocytes ; red blood - cells; casts (a) hyaline ( b ) finely granular ( c ) coarsely granular, ( d ) epithelial ( e ) other forms ; mucous cylindroids ; mucous strands.The microscopic examinations were made at three periods during each series, except in Series I. during which time the microscopic supervision of the urine had not been instituted. The examinations were made once during the fore period once or more during the preservative period and once near the close of the after period. Reviewing the data as a whole in regard to the appearance of these microscopical bodies in the urine the facts which appear prominently are the great variations in the number and character of these microchemical bodies. They occur constantly in some cases in very much greater abundance than in others. There are a few cases -in fact quite a number-where the relative abundance of these bodies seems to be increased during the administration of the preservative.There is a smaller number of cases in which the contrary fact occurs. I n the greater number of cases however, the administration of the preservative appears to have had no influence upon the relative abundance of these bodies. The data therefore as a whole cannot be regarded as conclusive respecting the influence of the preservative upon the number or kind of microchemical bodies occurring in the urine, There was no regular influence established relating to the effect of the preservative in increasing or decreasing the number of corpuscles in the blood. The data in individual cases are often contradictory and a general summary of them leads to no conclusive result.CONCLUSIONS. In the consideration of the action of preservatives of a mineral nature such a13 borax and boric acid it must be remembered that mineral substances play a double riile in animal and plant nutrition. First they may serve as real foods necessary t THE ANALYST. 367 the formation and nutrition of the tissues. In the second place they are necessary to the functional activity of the various organs of the body irrespective of any paxt they may take in direct nutrition. Hence the introduction of saline bodies which may or may not be of an anti-septic character may within certain limits have a favourable influence upon health and digestion. At the same time it should not be forgotten that all excess of such bodies iniposes upon the excretory organs an additional burden which while it might not impair their eEciency even for a number of years might finally produce a condition of exhaustion which would be followed by serious consequences.Especially is this remark true of the kidneys which appear to be a general clearing house for all the surplus of saline matters ingested in the foods. I t is admitted by all who have examined the subject in a critical way even by the users of preservatives that in certain maximum quantities the limit of toleration is reached in each individual and positive injury is done. But it is also well recognised that many if not all of the usual foods when used in large excess produce injurious results. The many cases of disease produced by overeating or by eating improperly-prepared or poorly-cooked foods or by eating at unusual times are illustrations of this fact.Upon this basis and upon the further statement that when used in extremely small quantities the preservatives in question cannot be regarded as harmful is founded the principal argument in favour of the use of the preservatives, aside from the fact that the foods themselves axe kept in a better and more whole-some state. I t is only proper to give to this argument full consideration and not to brush it aside as illogical and irrelevant. I t is evident that any attempt to determine experi-mentally the effect of extremely minute quantities of any preservative even when used continuously would not be likely to lead to any definite result. I n the fore-going data we have illustrations of the fact that even large quantities of the preservative employed-larger by far than would probably ever be found in any food product-do not always act in such a way as to permit of definite interpretation.The claim therefore that the use of such preservatives is justified when the amount is extremely small and when even these small amounts are used only at intervals and not continuously is worthy of careful consideration. An illustration which is pertinent may be taken from the particular preservatives with which the foregoing experiments have been made-namely boric acid and borax. One of the food products to which these preservatives are very commonly added is butter. This statement should not be taken to imply that in butter prepared for domestic use in this country borax is found to any considerable extent.When butter however is to be transported over long distances and necessarily kept a long while the addition of borax is very frequently practised. The dietetic data which have been accumulated in the course of this experiment show that the quantity of butter consumed daily varies from 30 to 70 grammes. Suppose as a maximum we say that the quantity of butter consumed in any one case daily is 100 grammes and that it contains 1 gramme of boric acid or an amount of borax equivalent thereto. The maximum quantity of boric acid used in a day in this case would be 1 gramme. I n point of fact however it would rarely if ever reac 368 THE ANALYST. this amount but even in those cases where butter is eaten freely probably 8 gramme would be about the maximum quantity consumed.Further than this 1 per cent. of boric acid or its equivalent in borax in butter is a very large quantity. Probably as a rule not more than one-half of 1 per cent. is employed. In this case the quantity of boric acid likely to be consumed by any one individual in a day would be reduced to 4 gramme. I n the case of meats preserved by borax although larger quantities are eaten than of butter it is not likely that any larger quantities of borax would be consumed. Thus it appears that those who habitually eat butter and meat preserved with borax might be consuming 4 gramme or a little more of boric acid per day. But preserved meats are not regularly eaten and hence the quantity mentioned is likely to be over-estimated.I t would be unwise to affirm in a case of this kind in the light of the data obtained by the experiments that such a minimum consumption oi borax and especially when not a continuous one would prove deleterious within any reasonable time of observation. The question then arises Does the absence of such proof or the impracticability of obtaining it serve as a justifiable excuse for the use of this preservative ? This question ought not to be decided alone because the principle of the decision must stand not only for boric acid and borax but for every preservative used in foods. I n other words whatever principle is established for judgment as to the use of boric acid in small portions must also be applied to the use of every other preser-vative used in foods.The principle must also be still further extended so that whatever may be established as regards butter or meat must be admitted in respect of every other substance used in food. Hence before admitting the full force of the argument based on minimal quantities the full significance of such an admission must be considered and the practically unlimited extent of its application acknowledged. This leads to the discussion of the fact that in the majority of cases the labour of freeing the system from added preservatives falls principally upon the kidneys. In the method of life in vogue in this country the kidneys are already hard-worked organs. Americans probably eat more freely than the citizens of alniost any other country with the possible exception of England.Large quantities of nitrogenous foods are consumed. In the breaking down of the nitrogenous tissues the kidneys are the chief organs for the excretion of the d6bris. The addition of any further burden therefore no matter how minute is to be deplored. If however the principle be admitted that injurious substances may be used in such small quantities as to be practicallyharmless then we find the way open for loading upon the kidneys many different functions in addition to those which they now discharge. If they may be justly called upon to eliminate the small quantities of boric acid added in food they cannot logically be freed from the necessity of eliminating also minute quantities of salicylic acid saccharin sulphurous acids and sulphites together with the whole list of the remaining preservatives which are eliminated principally through the kidneys.It would be useless to contend that the occasional consumption of small quantities of boric acid in a sausage in butter or in preserved meat would produce even upon delicate stomachs any continuing deleterious effect which could be detected by any of the means at our disposal; but naturally it seems that thi THE ANALYST. 369 admission does not in any way justify the indiscriminate use of this preservative in food products implying as it would the equal right of all other preservatives of a like charact,er to exist in food products without restriction. I t appears therefore that there is no convincing force in the argument for the use of small quantities unless it can be established that there is only a single pre-servative used in foods that this preservative is used in only a few foods that it will be consumed in extremely minute quantities and that the foods in which it is found are consumed at irregular intervals and in small quantities.On the other hand the logical conclusion which seems to follow from the data at our disposal is that boric acid and equivalent amounts of borax in certain quantities should be restricted to those cases where the necessity for them is clearly manifest and where it is demon-strable that other methods of food preservation are not applicable and that without the use of such a preservative the deleterious effects produced by the foods themselves, by reason of decomposition would be far greater than could possibly come from the use of the preservative in minimum quantities.I n these cases it would also follow, apparently as a matter of public information and especially for the protection of the young the sick and the debilitated that each article of food should be plainly labelled and branded in regard to the character and quantity of the preservative employed. The most interesting of the observations which were made during the progress of the experiments was in the study of the direct effect of boric acid and borax when administered in food upon the health and digestion. When boric acid or its equivalent in borax is taken with the food in small quantlities not exceeding Q gramme (79 grains) a day no notable effects are immediately produced. The medical symptoms of the cases in long-continued exhibitions of small doses or in layge doses extending over a shorter period shov in many instances a manifest tendency to diminish the appetite and to produce a feeling of fulness and uneasiness in the stomach which in some cases results in nausea with a very general tendency to produce a sense of fulness in the head which is often manifested as a dull and persistent headache.In addition to the uneasiness produced in the region of the stomach there appear in some instances sharp and well-located pains which, however are not persistent. Although the depression in the weight of the body and some of the other symptoms produced persist in the after periods there is a uniform tendency manifested after the withdrawal of the preservative toward the removal of the unpleasant sensations in the stomach and head above mentioned.The administration of boric acid to the amount of 4 or 5 grammes per day, or borax equivalent thereto continued for some time results in most cases in loss of appetite and inability to perform work of any kind. In many cases the person becomes ill and unfit for duty. Four grammes per day may be regarded then as the limit of exhibition beyond which the normal man may not go. The administration of 3 grammes per day produced the same symptoms in many cases although it appeared that a majority of the men under observation were able to take 3 grammes a day for a somewhat protracted period and still perform their duties. They commonly felt injurious effects from the dose however and it is certain that the normal man could not long continue to receive 3 grammes per day 370 THE ANALYST.I n many cases the same results though less marked follow the administration of borax to the extent of 2 grammes and even of 1 gramme per day although the illness following the administration of borax and boric acid in those proportions may be explained in some cases by other causes chiefly grippe. The administration of borax and boric acid to the extent of 8 grainiiies per day yielded results markedly different from those obtained with larger quantities of the preservatives. This experiment (Series V.) conducted as it was for a period of fifty days was rather a severe test and it appeared that in some instances a somewhat unfavourable result attended its use. On the whole the results show that 4 gramme per day is too much for the normal man to receive regularly. On the other hand, it is evident that the normal man can receive ij gramme per day of boric acid or of borax expressed in terms of boric acid for a limited period of time without much danger of impairment of health. I t is of course not to be denied that both borax and boric acid are recognised as valuable remedies in medicine. There are certain diseases in which these remedies are regularly prescribed both for internal and external use. The value which they possess in these cases does not seem to have any relation to their use in the healthy organism except when properly prescribed as prophylactics. The fact that any remedy is useful in disease does not appear to logically warrant its use at any other time. It appears therefore that both boric acid and borax when continuously administered in small doses for a long period or when given in large quantities for tt short period create disturbances of appetite of digestion and of health

ISSN:0003-2654    

DOI:10.1039/AN9042900357

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

370 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER J 0 U R N ALS. FOODS AND DRUGS ANALYSIS. The Influence of Various ‘‘ Fining ” Materials on the Composit,ion of Wine. K. Windisch and T. Roettgen. (Zcit. Untersuch. Nahr. P L ~ Gemm?uittd, 1904, viii., 279-283.)--Analyses are given of wines both before and after the latter had been treated with “fining” materials, such as casein, milk, wood charcoal and animal charcoal. The results show that casein slightly increases the amount of mineral matter in the wine, but is without influence on the tannin and nitrogenous matters. Milk also slightly increases the quantity of mineral matter present in the wine, whilst it removes a considerable portion of the tannin, owing to the albumin it contains. By treating wine with animal charcoal, a distinct diminution in the amount of tannin takes place, but no nitrogenous matters are precipitated.Wood charcoal only slightly diminishes the tannin contents of the wine; it increases the mineral matter to a small extent, but is without influence on the nitrogenous matter. The assumption that “ fining ” materials considerably alter the composition of wines is probably dueTHE ANALYST, 371 to the very bulky sediment which is obtained. Experiment shows that a solution 0.01 gramme of casein, added to 100 C.C. of wine, produces a voluminous precipitate, which settles to form a layer of appreciable thickness. This precipitate, however, weighs but little more than 0.01 gramme. w. P. s. Margarine containing Ammonia. K. Fischer and 0. Grunert. (Zeit.Unter- such. Nahi.. u?zd GeTzzLssmittel, 1904., viii., 414-416.)-During the examination of a sample of margarine, it was noticed that the aqiieous layer obtained on melting the sample was strongly alkaline in its reaction. This alkalinity was due to the presence of ammonia, the quantity of the latter contained in the margarine being 0.017 per cent. I n other respects the sample was of normal quality. Further tests showed that no appreciable amount of the ammonia was c.ombined with fatty acids, w. P. s. the probability being that it was present as the carbonate. Quantitative Estimation of Cellulose in Foods and Faeces. Oscar Simon and Hans Lohrisch. (Zeit. Phys. Chem., 1904, xlii,, 55 ; through Chem. Zeit. Rep., 1904, xxi., 254.)-This process is based upon the insolubility of cellulose in 50 per cent.potash solution. Ten grammes of the finely-powdered substance are heated on a water-bath for one hour with 50 per cent. KOH. After cooling, 3 to 4 C.C. of hydrogen peroxide are added, and, if necessary, further heated until the greater part of the cellulose is in solution. The mixture is again cooled, one-half volunie of 96 per cent. alcohol added; should the mixture of the liquids not be complete, 6 to 7 C.C. of concentrated acetic acid are added, Precipitation of the dissolved cellulose is complete ; proteids, etc., remain in solution. When cold the precipitate is filtered off, thoroughly washed with water and dilute acetic acid, finally with alcohol and ether, and weighed. The nitrogen never exceeds 1 per cent. The nature of the cellulose has great influence on its solubility ; potato cellulose is largely soluble, wheat cellulose less so, while prepared celluloses, as cotton or filter-paper, are quite insoluble.H. A. T. The Proteids of Wheat Gluten. J. Konig and P. Rintelen. (Zezt. Unter- such. Nahr. 7cnd Geizussnaittel, 1904, viii., 401-407.) - The following method is proposed for the separation of the various proteids extracted from gluten by 65 per cent. alcohol. Of these, a portion, the so-called gluten-fibrin, is soluble in 90 per cent. alcohol; another portion, mucedin, is soluble in 40 per cent. alcohol, whilst gliadin is insoluble in the latter spirit. Gluten-casein is practically insoluble in any of these alcoholic solutions. The details of the method are as follows: 2 to 3 grammes of the washed gluten are moistened with absolute alcohol and finely divided, after which the mass is treated in a cylinder with alcohol and ether to remove fat.The small amount of proteid dissolved by the absolute alcohol is precipitated on adding the ether, and is collected and added to the cake of gluten. The latter is now placed in a linen bag, suspended in a cylinder, and covered with 65 per cent. alcohol. The The gluten is then lightly pressed, air-dried, and again powdered.372 THE ANALYST. solvent is frequently renewed, a considerable quantity-several litres-being used for the extraction. To the clear alcoholic extract obtained sufficient absolute alcohol is added to bring the alcoholic strength up to 90 per cent. A white precipitate is obtained, which may be made to settle or collect together by cooling the solution in ice-water and shaking.After filtration, the filtrate is evaporated, the residue, which also contains sugars and fat, is rubbed down with water, again dried, and extracted with ether. The residue of gluten-fibrin so obtained may still contain a little fat. To remove this, the mass is dissolved in dilute alcoholic potash, the solution shaken out with ether, and the alkaline solution exactly neutralized with hydrochloric acid and evaporated. The precipitate, consisting of gliadin and mucedin, obtained from the 90 per cent. alcohol solution, is dissolved in 65 per cent. alcohol, using sufficient of the latter to form a practically saturated solution. One-half the alcohol is now distilled off', and the residual liquid allowed to cool.Gliadin separates out and adheres to the sides of the flask. The clear solution is poured off and evaporated to two-thirds its original volume. On cooling, a mixed precipitate of mucedin and gliadin is Obtained, which is rejected. The clear solution separated from this precipitate, on evaporation, yields a residue consisting of mucedin. Analyses of these three proteids, separated from various glutens, are given. From the differences in their compositions, and in their solubilities in alcohol, the author concludes that they are actually three separate compounds and not one, as has been suggested by other observers. w. P. s. Detection of Artificial Colouring Matters in Mustard. P. Bohrisch. (Zezt. Uiztersmh. Nahr.uizd Geimssnzittcl, 1904, viii., 285, 286.)--The usual test for aniline colours, consisting in steeping woollen threads in a solution of the substance under examination, fails in the case of mustard. Kven pure samples dye the threads yellowish, the coloration becoming almost bright yellow on treatment with ammonia. If, however, the dyed woollen threads be washed with water, all the yellow colora- tion is removed, should the sample consist of genuine mustard. When aniline colours are present, the bright yellow colour remains. . The presence of turmeric in mustard may be detected by treating 10 grammes of the dry sample with 30 C.C. of absolute alcohol, allowing the mixture to stand for twelve hours, and then filtering. Strips of filter-paper are partially immersed in the alcoholic filtrate, and the yellow zone obtained is tested with boric acid solution.Should turmeric be present, the characteristic red coloration is obtained on dyeing the strip. Pure mustards give a yellowish-brown to gray-brown band on the strip of paper. w. P. s. Alteration i n the Composition of Asparagus when stored in Water. E. Windisch and P. Schmidt. (Zed. U I ~ ~ C I . S Z L C ~ . N ~ L Y . und Geizussmittel, 1804, viii., 352-355.)-As cut asparagus rapidly loses its freshness when kept, it is a market custom to store it in water in a dark cellar. To ascertain what changes take place during this treatment, the authors carried out a number of experiments.THE ANALYST. 373 Saponifica- tion T'alue. The results show that the asparagus absorbed a considerable amount of water- 12.16 per cent.in five days-whilst at the same time some of its constituents were dissolved out. I n five days 5.02 per cent. of the extractive matters, 6.30 per cent. of the nitrogen, and 8-36 per cent. of the mineral matters contained in the original asparagus were extracted by the water. By coating the cut surfaces of the sticks with paraffin the extraction was considerably diminished, but the absorption of water by the asparagus was not affected. When kept in the open air in a cool room the asparagus lost 23.10 per cent. of water in six days. Stored for the same time in an ice chest, the loss only amounted to 9.68 per cent. w. P. s. Essential Oil, l'er Cent. Refractive Index of Clove Oil. W. H. Simmons. (Chem. News, xc., 146.)- The author recommends the determination of the refractive index, together with the specific gravity and percentage of phenols, in the examination of clove oil.The refractive index for pure oils is approximately proportional to the amount of eugenol present, for which n,20" = 1.5412. A. G. L. Very pale yellow Yellowish-brown Pale yellow Yellowish-brown With greenish tint Pale yellow >, Copaiba Balsam from Surinam. L. van Itallie. (Jozmz. Pharm. C h k , 1904, xx., 337-346.)--hccording to Pool, this balsam is always very fluid when fresh, and thick products are due to resinification or adulteration. Seven samples examined by the author gave the following results : Very fluid Syrupy Very fluid Syrupy - - Very fluid Sample. A ... B ... c ... D ... E ... F ... G ...Colour. Consistency. Specific 0.9066 0.9599 0.9096 0.9611 0.9600 0.9535 Acid Talue. 15.7 59.19 14-65 59 a00 33.8 53.5 - 26.1 77.4 25.2 75-8 45.4 43.2 - ~ 69.1 42.3 71.6 41.0 52.3 61.7 - The essential oil was determined by heating the balsam on the water-bath and finally in the oven at 110" C. The balsam is not completely soluble in 5 parts of absolute alcohol, but dissolves readily in chloroform, petroleum spirit and carbon bisulphide. When shaken with a third of its volume of 10 per cent. ammonia solution, an emulsion is formed, from which, on stand- ing, drops of essential oil separate. On shaking the Surinam balsam with an 80 per cent. solution of chloral hydrate, the essential oil separates out on the surface, but the solution of the resin does not assume a special colour, such as Blauch found to be the case with Gurjun balsam.A very characteristic reaction for the Surinam balsam is the blue coloration obtained on adding a drop of sulphuric acid to a mixture of 1 drop of the balsam with 1 C.C. of acetic anhydride. The essential oil was found to contain a sesquiterpene alcohol (C,,H,,O) giving the reactions of cholesterol derivatives, a small amount of cadinene, and at least two374 THE ANALYST. sesquiterpenes. The liquid portion of the essential oil, after separation of the alcohol crystals, was a viscous liquid, which became light yellow on standing. It had the following characteristics : Specific gravity at 15" C.,* 0.9052 ; saponification value, 6.7; acetyl value of saponified oil, 28.4; and specific rotation, a,,= -10.3 in 100-millimetre tube.When distilled under normal pressure, the principal part passed over between 240" and 270" C., only a few drops distilling below 240" C. Between 2'70' and 280" C. a small amount of a pale-green empyreumatic product was distilled, whilst the residue in the flask was a dark-brown substance which solidified on cooling, and dissolved in ether, forming a solution with a strong green fluor- escence. C. A. M. Some Colour-Reactions of Strychnine and Brucine. C. Reichard. (Chem. Zeit., 1904, xxviii., 977-979.)-The following reactions are described : On adding a drop of a solution of a strychnine salt to a drop of dilute solution of cupric nitrate and evaporating the mixture, the edges of the solution as it dries become deep green in colour ; the addition of stannous chloride to the dry residue changes the green colour to4 violet, which latter coloration again beconies green when dry.A solution of strychnine nitrate treated with a drop of platinum chloride and concentrated sulphuric acid gives a, dark-red coloration on warming the mixture ; brucine similarly treated gives a yellow coloration. When drops of hydrogen peroxide, a solution of strychnine, and sulphuric acid are mixed, a blue solution is obtained having yellow edges. After a time the blue colour changes to yellow ; ether does not dissolve this latter colouring matter. Sulphuric acid, strychnine, and titanic acid yield, on warmiiig, a blue coloration, changing to yellow on standing or further heating, and a similar coloration is obtained with the same reagents in the case of brucine, but the addition of water discharges the colour, whilst the strychnine coloration remains yellow on dilution.A drop of a solution of a strychnine salt mixed with potassium hydroxide and evaporated gives a residue, which is turned blue by stannous chloride ; brucine similarly treated yields no coloration. Solutions of strychnine, when mixed with potassium or ammonium persulphate and hydrochloric acid, remain colourless, whilst brucine gives a bright-red coloration, only becoming colourless after I a long time. This last reaction is very useful for detecting the slightest trace of brucine in solutions of strychnine. On heating, the strychnine mixture turns yellow. w. P. s. A New Method for the Detection of Saccharin.E. von Maler. (Farmax. JOWL, 1904, 1089 ; through Chenz. Zeit. Rep, 1904, xxii., 270.)-Schmidt's method, in which the sulpho group of the saccharin is replaced by a hydroxyl group by fusion with caustic alkali, and the resultant potassium salicylate detected by ferric chloride, is unsatisfactory. Not only must the temperature of fusion be care- fully regulated, but the presence of any salicylic acid in the substance would also render the reaction inaccurate. 15" 15 * Probably Ls, Init w.iLtcr teniperature not given.TEE ANALYST. 375 The author fuses the substance with metallic potassium or sodium, converting the sulpho group into sulphides, which can be detected by sodium nitroprusside. H. A. T. Report and Itecommendations with Reference t o the Tests for the Detection of Arsenic in the Drugs of the British Pharmacopmia.W. R. Dunstan and H. H. Robinson. (Presented to the Phawn. Committee of the Gen. Med. Co~c?aci~, May, 1904.)-The results of investigations regarding the validity of the present tests for arsenic, and the best processes to be adopted in the next edition of the British Pharmacopceia, are given in this report. With the desire that the standard process should be such as could readily be applied by a qualified pharmacist without com- plicated apparatus, the test chosen is that proposed by Mayenqon and Bergeret (Comptes Rend., 1874, lxxix., 118), which depends on the production by arseniuretted hydrogen of a stain on paper soaked in mercuric chloride. The Marsh-Berzelius test was excluded, as requiring complicated apparatus, extreme purity of the reagents employed, and continuous attention during its performame. Precise instructions are given for carrying out the test recommended, and for its application to certain drugs. The stain decided on as the standard for comparison, and as showing that a drug contains an inadmissible amount of arsenic, is that given by 0.012 milligramme of the element arsenic, which is equivalent to 0-016 milligramme of arsenious oxide. The limiting quantity of arsenic which should be regarded as rendering a drug impure is fixed at 3 parts of arsenic per million, or :& grain of arsenious oxide per pound. This limit applies only to drugs administered in small doses. Tartaric and citric acids should not contain more than & grain of arsenic per pound. The following limits are proposed for drugs which are not readily freed from arsenic in their manufacture : Iron, 0.03 per cent. ; antimony sulphides, 0.03 per cent. ; phosphorus, 0.02 per cent. Ferrous sulphate, and those iron drugs which are made from it, fall under the general limit, as they can be obtained free from arsenic. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9042900370

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

TEE ANALYST. 375 ORGANIC ANALYSIS. The Fatty Oil of the Seeds of “Carthamus Tinctorius.” G. Fendler. (Communication of Pharm. Inst. of Berlin University to Chem. Z e d , 1904, lxxiv., 867.)-This oil, procured by extraction of the seeds with ether, is of a golden yellow colour, and, though at first inodorous, rapidly becomes rancid. In thin films the oil dries completely within six days, the gain in weight being : ,? 40 8 , ... ... 4.3 ,, 9 , 64 9 7 . . . 6.4 ,, ,) 136 9 , ... ..- 7-5 ,, After 18 hours ... . . . 0.6 per cent. The constants are : Specific gravity, 0.9266 ; melting-point, - 5’ C. ; Reichert- Meissl number, 0.0 ; saponification number, 191.0 ; iodine number (Hubl), 142.2 ; unsaponifiable matter, 0-708 per cent. ; Zeiss butyro-refractometer at 40’ C., 65 ; free376 THE ANALYST.fatty acids (as oleic acid), 5.84 per cent., figures well agreeing with those given by Benedict-Ulzer (Analyse der Fettej. The fatty acids have the following constants : Specific gravity, 0.9135 ; melting- point, 17" C. ; saponification number, 199.0 ; mean molecular weight, 251.8 ; acetsyl acid number, 154.5 ; acetyl number, 52.9 ; acetyl saponification number, 207.4 ; iodine number, 148.2. H. A. T. Analytical Notes on Mineral Oils. Rudolf Nettel. (Chem Zeit., 1904, lxxiv., 867.)-For the determination of water in crude oil, 100 C.C. of the oil are mixed with an equal volume of benzene in a separating funnel, shaken for five minutes with 50 C.C. of -& HCl, and then allowed to stand at 65" for half an hour. The greater part of the acid separates; 25 C.C.are drawn off, and titrated with & alkali. The water present in the oil acts as a diluent of the Fc acid, and the difference between the observed and the original acidity gives the percentage of moisture. Two determinations on the same sample gave the following figures : A. 25 C.C. & HC1 required 23.7 C.C. & NaOH-2.6 per cent. of water. B. 25 C.C. ,, ,, 23.8 C.C. ,, =2*4 per cent. ,, In a sample of dry oil 25 C.C. ihi HC1 required 24.98 C.C. & NaOH, indicating coin- plete absence of moisture. After addition to this sample of 6.2 per cent. of distilled water, 25 C.C. required 21.9 C.C. & NaOH, equal to 6.4 per cent. of water. For the determination of the solidifying-point of lubricating oils, the author drops a grain of shot (diameter, 14 millimetres) from a standard height into the oil at each successive lowering of the temperature by I" C., the point at which the shot remains on the surface being taken as the solidifying-point of the oil.H. A. T. Analysis of Otto of Rose. W. H. Simmons. (Chemist and DyzLgqist, 1904, lxv., 703.)-In continuation of his previously published work on the iodine absorp- tion of Otto of rose (ANALYST, 1904, 175) the author has applied the process to several samples of this season's oil, with results which fully confirm his former opinion as to the value of this test in judging the purity of Otto of rose. Five oils, which from their other constants appeared to be genuine, had iodine values varying from 189 to 192. Five other samples of a, suspicious character gave values from 199 to 209.To test the value of the refractive index for detecting adulteration in Otto of rose this constant was determined for thirty-six samples, twenty-three of which there was every reason to believe were genuine, the other thirteen being of doubtful quality. The genuine oils had refractive indices, varying from 1.4592 to 1.4654, whilst the other samples gave values from 1.4615 to 1.4770. X sample purposely adulterated with 25 per cent. of artificial Otto gave a reading of 1.4655, and another, containing 15 per cent. of palmarosa oil, 1.4612. These results show that the generally accepted limits, 1.4600 to 1.4650 or even 1.4670, are too wide for the constant to have much value, as they cover many adulterated samples. On the other hand, the iodine valueTHE ANALYST.377 readily revealed the adulteration in the last-mentioned samples, the values being 215 and 205 respectively, and, in fact, was the only figure which did so. w. P. s. The Estimation of Tanning Matter without the Use of Hide Powder. H. Wislicenus. (Zeits. f. a?~gezu. Chem., 1904, xxv., 801.)-Instead of hide powder the arxthor uses aluminium oxide or hydroxide, prepared by the action of dilute caustic soda upon aluminium in the presence of mercury. I t is claimed that this absorbent is cheap and easily prepared in a uniform condition, that it is rapid in its action, and yields concordant results. For the preparation of the porous alumina absorbent 100 grammes of aluminium filings in grains of about 1 millimetre diameter are shaken with a 5 per cent.aqueous caustic solution, and as soon as hydrogen begins to come off freely the liquid is poured away and the filings washed well under the tap. After this treatment with caustic soda and washing has been repeated, a little mercuric chloride solution is added, and the filings are washed again. The aluminium-mercury couple is then allowed to stand with an equal quantity of water, to which some ether and alcohol may be added. The heat set free by the oxidation causes the liquid to evaporate, and a dry mass is obtained, from which fine aluminium hydroxide can be separated by sifting through a fine sieve. The material may either be dried in a desiccator, in which case it has the composition Al(OH),, or it may be ignited, and so con- verted into A120,.In making an estimation, 2.5 to 3 grammes of the hydroxide, or 2 to 2.5 grammes of the oxide, are gradually added, with constant shaking, to 50 to 100 C.C. of the tannin solution. The whole is then allowed to stand for some hours until the liquid is clear, and a drop of it gives no colorat'ion with an iron solution. The material absorbs far more rapidly than hide powder. The alumina may now be filtered off on to a tared filter, washed with cold water, dried, and weighed. The amount of tannin is given by the gain in weight of the powder; the estimation can be checked by burning off the tannin and reweighing the alumina, but there is danger of losing some of the fine powder during the ignition. As an alternative, the total extract and " non-tannin " may be estimated by evaporation, as in the hide powder process.Sugars are not absorbed by the alumina powder; gallo-tannic acid is, biit can be removed almost completely by washing with hot water. Comparative experiments showed that in the case of commercial tannins and chestnut extracts the results are almost identical with those obtained by the hide-powder process, but that with pine and oak bark and oak wood the agreement is not so good. A. 111. On the Presence of Hydroquinone in the Bear-Tree. G. Rivihe and G. Bailhache. (BUZZ. SOC. Chzm., 1904, xxxi., 1104-1107.)-The authors have isolated hydroquinone from the leafy buds of the pear-tree, from 3 to 5 grammes per kilo. being found. The material was digested for several days with cold alcohol, the alcoholic extract evaporated, and the residue treated with boiling water and filtered378 THE ANALYST.from the chlorophyll and resins. The filtrate was shaken with ether at intervals for forty-eight hours, and the ethereal extract on evaporation left a mass of crystals of impure hydroquinone, which, when purified, gave all the usual reactions. C. A. MI. Determination of Lecithin in Plants. E. Schulze. (Chem. Zeit., 1904, xxviii., 751, 752.)-The author mentions that both the ethereal and the alcoholic extracts of the plant should be used for the determination of the lecithin, as the latter is dissolved by both solvents, I t is also shown that absolute alcohol extracts no phosphorus- containing compound other than lecithin from plants or seeds. With regard to the statements that lecithin is slowly decomposed at temperatures above 60" C., and that this temperature should not be exceeded during the alcohol extraction, it should be pointed out that a considerable proportion of the lecithin exists in plants in combina- tion with albuminous substances, and that the treatment with alcohol has for its purpose the breaking-up of these compounds.Whether this is attained at a temperature below 60" C. remains to be proved experimentally. I t is usually assumed that 100 parts of lecithin contain 3.84 parts of phosphorus corresponding to the phosphorus contents of distearin-lecithin, or the average amount of phosphorus (3-94) contained in dipalmitin, distearin, and diolein-lecithin is taken as the factor for calculating the phosphorus found in lecithin.Lecithin, however, occurs in combination with other fatty acids, lecithin compounds, containing from 2-52 to 2.3 per cent. of phosphorus, have been obtained from rye, barley, and malt. The correct factor is, therefore, not accurately known. w. P. s. Analysis of Tobacco. R. Kissling. (Chem. Zeit., 1904, xxviii., 775, 776.)-The folIowing methods are given for the determination of nicotine, resins, and non-volatile organic acids (citric, malic, and oxalic) in tobacco. Nicotine.-Ten grammes of the powdered tobacco are mixed with 10 grammes of powdered pumice stone and 10 grammes of sodium hydroxide solution (50 grarrirnes per litre). The somewhat moist mass is extracted with ether in a suitable apparatus for several hours. After slowly evaporating off the ether, the residue is dissolved in dilute potassium hydroxide solution and steam-distilled. Each 100 C.C.of distillate is separately titrated with standard sulphuric acid, using luteol as indicator, the fifth distillate being usually free froin nicotine. One molecule of sulphuric acid corresponds to 2 molecules of nicotine. Resins.-Thirty grammes of tobacco are extracted with light petroleum spirit for eight hours, and the residue from the petroleum spirit extract dried at 80" C. for two hours and weighed, This residue, consisting of resin, wax, nicotine, and volatile fatty acids, is dissolved in absolute alcohol and cooled to 0" C. The wax separates Out, and is collected on a filter. After evaporating the alcohol from the filtrate, the latter is acidified with sulphuric acid and steam-distilled to remove volatile acids.The distillation residue is then rendered alkaline, and again steam-distilled to drive off the nicotine. The resin is finally obtained from the residue in the flask in the usual way.THE ANALYST. 379 The tobacco which has been extracted with petroleum spirit is now freed from the latter, and extracted with ether. I t is sufficient to treat with hot water the small amount of resin, etc., obtained to remove nicotine, and then to dry the residue of resin at 90" C. The tobacco, after removing the ether, is extracted a third time with 99 per cent. alcohol. The extract, after evaporating the alcohol, is acidified and steam- distilled. The resin is then separated from the aqueous residue, dissolved in alcohol, filtered, evaporated and dried at 100" C.The amounts of resins obtained by the author from six samples of tobacco (Brazilian and Havana) were : petroleum-spirit- soluble, 3.50 to 8.63 per cent. ; ether-soluble, 0.39 to 1.19 per cent. ; alcohol-soluble, 1.71 to 2-68 per cent. Non-uoZatile Organic Acids.-A mixture of 10 grammes of tobacco, 10 grammes of powdered pumice stone, and 10 grammes of dilute sulphuric acid (20 per cent.) is extracted with ether for twenty hours. The residue obtained from the extraction after distilling off the ether is dissolved in water, and made up to 100 c.c ; 50 C.C. of this solution are titrated with barium hydroxide solution, and the barium salts separated by adding alcohol to the solution until it contains 20 per cent. of alcohol.The mixture is quickly filtered, and the precipitate consisting of almost pure barium citrate washed with 20 per cent. alcohol. On adding sufficient alcohol to the filtrate to bring the strength of the latter up to 70 per cent., barium malate is precipitated. The oxalic acid is determined in the remaining 50 C.C. of the solution by the usual methods. The following results were obtained in the above-mentioned samples of tobacco : oxalic acid, 1.84 to 2-77 per cent. ; malic acid, 1.53 to 3.95 per cent. ; citric acid, 3.25 to 7.33 per cent. All the results are calculated on the dry tobacco. w .P. s. On the Treatment of Urine before the Determination of Urea. C. Frabot. ( A m . de Chim. anal., 1904, ix., 372, 373.)-Urine treated by means of lead acetate, phosphotungstic acid (Moreigne's reagent), etc., gives the characteristic blue coloration when tested by the method described in the abstract on p.384. The author, there- fore, concludes that in the ordinary methods of treatment the uric acid is not completely precipitated. C. A. M. Volumetric Determination of Methylene Blue. L. Pelet and V. Garuti. (BUZZ. SOC. Chim., 1904, xxxi., 1094-1097.)-The method is based on the precipitation of the methylene blue by means of certain acid dye-stuffs that combine with it to form more insoluble compounds, the end-point of the reaction being shown by the change of colour in the solution. The most suitable dye-stuffs were found to be crystalline Ponceau, carmine in the state of the sodium salt, orange pyramine, and cotton brown. Certain acid yellows-e.g., yellow naphthol S.-yielded an insoluble derivative, but it was nearly impossible to distinguish the change of colour at the final point of the reaction.In the determination a definite volume of the solution of methylene blue is treated with the solution of the reagent, which is added, little by380 Ponceau. Carmine. THE ANALYST. Orange pyramine. Cotton Brown. little, until the change of colour is seen in the stain made by a drop of the liquid on filter-paper. The solutions of acid colouring matters are first standardized on 8 solution of pure methylene blue before being tried on commercial samples. The following results were obtained with two samples, of which definite quantities were weighed and allowance made for the proportion of ash and moisture present : No.1 No. 2 I I Amount found by Titration with ~ _ _ _ ~ - ~ ~ _ _ - Gramme. (tramme. Gramme. Grainine. Gramme. 0.684 0.688 0.684 0.677 0.668 0.705 0.699 0.687 0.703 0.699 The conipound formed with crystalline Ponceau has the formula C,,H,,N,S,07, and contains 2 molecules of blue to 1 of Ponceau, whilst the carmine compound probably has a composition corresponding to the formula C,,H,,N,SO,,. The error in the determination is within about 3 per cent. c. -4. M. Parchment-paper Containing Boric Acid. K. Windisch. (Zezt. U?itersmh. Xahi.. imd Gemssnzittel, 1904, viii., 417.)-Out of 124 samples of parchment-paper examined, only 17 were quite free from boric acid (or borax), whilst 101 samples gave a strong, and 6 samples a feeble, reaction for boric acid.I n four cases the quantity of this acid was determined, the amounts found varying from 0.384 to 1.130 grarunie per 100 grammes of paper. This investigation was undertaken because faint traces of boric acid were detected in the outside parts of a sample of margarine, whilst the interior of the same contained none. The paper in which the sample was wrapped probably contained boric acid. An experiment was then carried out, in which margarine was wrapped in paper containing boric acid, so kept for a few days, and then tested. The result showed that margarine readily takes up boric acid from these wrappers, the outer layers of the sample having absorbed as much as 0.0186 per cent. of boric acid in ten days. w. P. s. The Effect of the Alkalinity of Glass on the Accuracy of Kjeldahl Nitrogen Determinations. K. Barelt and H. Schoenewald. ( Woclzeizsclw. Bmuemi, 1904, 523 ; through Chem. Zeit. Ilep., 1904, xxii., 969.)-In these experiments a long air-cooled tube of soda-glass was used as condenser for the distillation of water under conditions similar to those of the Kjeldahl process, and the distillation con- tinued for from one-half to three hours. With an old tube which had been frequently employed for this purpose, the error only once exceeded 0.4 per cent. (calculated as albumin). Using new glass this figure was greater by some 0.1 to 0.15 per cent. (of albumin), and the authors suggest that all glass should be thoroughly steamed before use.THE ANALYST. 381 Attention is drawn to the fact that in an actual ammonia distillation the error would be greater, owing to the solubility of the alkalies in steam containing ammonia. H. A. T.

ISSN:0003-2654    

DOI:10.1039/AN9042900375

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE ANALYST. 381 INORGANIC ANALYSIS. H. A. Guess. (Trans. Am. Inst. Min. Eng., 1904; through Chem. Zeit. Rep., 1904, xxi., 287.)-The author suggests a chromic acid method as being superior to the usual titration with ammonium molybdate or ferrocyanide. Excese of standard potassium chromate is added to the lead solution, filtered, and to the filtrate 25 C.C. of 50 per cent. HC1 and 0.5 gramme KI are added. The liberated iodine is then titrated with thiosulphate, and this gives the excess of chromic acid. For a more rapid method 1 to 5 grains of the ore are heated with 3 to 5 C.C. of HNO, and 15 C.C. of HCl. To the mixture, evaporated to 8 C.C. and rendered alkaline with ammonia, excess of 80 per cent. acetic acid is added. Should any lead remain undissolved, concentrated ammonium acetate is added until solution is complete.After filtration, an excess of chromate is added, the whole again filtered, and the precipitate washed with 0.5 per cent. acetic acid. The filtrate is then titrated as above. Commercial Lead Analysis. Great accuracy is claimed for this method. H. A. T. The Assay of Alloys of Platinum, Gold, and Silver. A. Hollard and L. Bertiaux. (Bull. SOC. Chinz., 1904, xxxi., 1030-1034.)-The ordinary method of assaying makes no allowance for the solubility of the gold in acids or for the reten- tion of lead by the silver button obtained by cupellation, though the determination of the platinum and gold together by cupellation with lead and silver and treatment of the button with sulphuric acid gives accurate results. The loss in the determina- tion of gold on cupelling about 0.3 gramme of the alloy containing 0.2 gramme of gold and 0.1 gramme of platinum in the presence of 3 parts of silver, and treatment of the button with 20 C.C.of nitric acid of specific gravity 1-16 (20" Bif.), and then with 30 C.C. of nitric acid of specific gravity 1-28 (32" B6.), amounted on the average to 0.002 gramme. This amount ought, therefore, to be added as an empirical factor to the weight of gold obtained. Silver.-The following method is recommended : The finely-divided alloy is treated with aqua reyia consisting of 1 part by volume of nitric acid and 5 parts of hydro- chloric acid, and the solution evaporated to the consistency of a syrup on the water- bath. The residue is taken up with nitric acid and the liquid evaporated to dryness, this being twice repeated to eliminate the hydrochloric acid.Finally, the residue is taken up with 2 C.C. of nitric acid, 2 drops of hydrochloric acid, and several C.C. of water, and the liquid boiled, when the mixture ought practically to dissolve. The solution is now diluted to about 100 C.C. and again boiled, and the silver chloride collected, washed, and dissolved in 30 C.C. of a 20 per cent. solution of potassium cyanide. This solution is diluted to 150 c.c., and electrolysed with a feeble current382 THE ANALYST. (0.1 amp8re) in the authors’ small apparatus. dilute nitric acid and tha silver determined volumetrically. Lastly, the deposit is dissolved in C. A. M. The Separation of Palladium by Acetylene. H. Erdmann and 0.Makowka. (D. Chem. Ges. Ber., 1904, 2694; through Chem. Zeit. Rep., 1904, xxi., 253.)- Palladium is unique among metals in being precipitated from an acid solution by acetylene gas or by water saturated with acetylene. I n a strongly acid solution the separation is quantitative. The flocculent precipitate is pale brown in colour, very soluble in ammonia, is not explosive, and, on ignition, yields pure palladium. The authors state that the presence of copper does not interfere with the reaction. H. A. T. The Determination of Carbon and Sulphur in Iron and Steel. A. Mueller. (Chem. Zeit., 1904, lxviii., 795.)-The author has designed an improved and more compact form of the Corleis apparatus for carbon deter- mination. I n that apparatus any carbon given off as hydrocarbon vapour passes through a platinum combus- tion tube, and is absorbed by soda-lime as CO,. The platinum capillary combustion tube is given the shape shown in Fig.2, thus great heating surface is obtained in a small space. The short connecting portion takes up all strains, so that the life of the tube is much prolonged. A special compound gas-absorber is used for drying the gas. The lower, spiral part of this contains phosphor-sulphuric acid, and the short, straight portion (above the small bulb) is filled with glass-wool and phosphorus pentoxide. Long rubber connecting-tubes for the cooler are avoided by making the standard out of a piece of wide tube, into which a smaller is inserted. For the determination of sulphur, the gases pass through a combustion tube of quartz glass, and are finally absorbed in cadmium acetate solution.This apparatus, which has proved most satisfactory, is manufactured by Messrs. C. Gerhardt, Marquart’s Lager Chemischer Utensilien, Bonn, The construction can be seen from the figure. EL A. T.THE ANALYST. 383 A Method of Determining Chromium and Iron in the Presence of each Other. (Zeit. anal. Chem., 1904, xxxiv., 506-508.)-This is based upon the fact recorded by Zimmermann that chromic salts are quantitatively reduced by zinc and sulphuric acid to chromous salts, and also on the fact that ferric salts are reduced by sulphur dioxide to ferrous salts, whilst chromic salts remain unaltered. The solution of the mixed salts, which must not contain more than 0.05 gramme of chromic oxide, is treated with sulphur dioxide, the excess of which is expelled by boiling the liquid, while a current of carbon dioxide is passed through it.After cooling, the amount of iron is determined by titration with standard permanganate solution. The solution is now treated with zinc and sulphuric acid, and heated on the sand-bath until it assumes a clear blue colour, after which it is again oxidized by permanganate, as in Zimmermann’s method (Liebig’s Am., 1882, ccxiii., 322), the amount of chromium being obtained from the difference between the two titrations. The reactions underlying the method are shown in the following equations : B. Glasmann. II. REDUCTION. (a) Cr,O, + Ee,O, + SO, = SO, + 2Fe0 + Cr20,. ( b ) Cr,O, + 2Fe0 + H, = 2Cr0 + 2Fe0 + H,O. 11. OXIDATION.( a ) Cr,O, + 2Fe0 + 0 = Ee,O, + Cr,03. ( b ) 2Cr0 + 2Fe0 + 0, = Cr,O, + Fe,O,. The test results given show that the method is extremely accurate, and the author considers that it will be found valuable in the analysis of chrome iron stone and chrome iron ores. C. A. M. A Rapid Method of Determining Metallic Aluminium in Aluminium ( A m . de Chim. mal., 1904, ix., 381, 382.)-This is an Powder. application of Webl’s method of analysing zinc powder, and is based on reaction : E. Kohn-Abrest. 3Fe,(SO,), + 2A1= AlJSO,), + 6FeS0,. I n the determination 0.5 gramme is heated with an excess (20 grammes) of ferric sulphate and about 50 C.C. of water in a flask through which a current of carbon dioxide is made to pass throughout the reduction. The flask is kept on the water- bath for about an hour, after which time the aluminium powder will have completely disappeared and the ferric sulphate have been almost dissolved.After rapid cooling in a current of carbon dioxide, solution will be complete, and the liquid can now be acidified with 20 C.C. of concentrated sulphuric acid, then diluted to 250 c.c., and an aliquot portion titrated with standard permanganate solution containing, c.g., 3.163 grammes per litre, 1 C.C. of which corresponds to 0.00062968 gramme of aluminium. A commercial sample of the powder yielded by this method 91.4 per cent. of aluminium. The author has found that the bulk of the silicon in aluminium powder is present in the state of silica, and of the other common impurities only iron in the metallic state would affect the results.C. A. M.384 THE ANALYST. A Colour Reaction of Tungsten. C. Frabot. ( A m . de C h i w anal., 1904, ix., 371, 372.)-The blue coloration produced on adding a few drops of a solution of uric acid, followed by sodium hydroxide solution to tungstic hydrate (WO:,.H,O), is due to the formation of the intermediate blue tungsten oxide by reduction. The reaction is capable of detecting 1 part of uric acid in 100,000, and conversely can be used for the detection of tungsten in metallurgical compounds, such as ferro-tungsten. For this purpose the tungsten should be converted into tungstic acid by slow ignition in a current of air and the residue tested after elimination of other metals. Traces of tungsten can be detected in this way in the presence of a large excess of silica.Molybdenum, which gives an analogous reaction, can be separated from tungsten before applying the test for the latter. C. ,4. M. Borax of Abnormal Composition. L. Spiegel. (Chem. Zed,, 1904, xxviii., 750, 751.)--A sample of borax examined by the author gave consistently abnormal results on titration with + acid. As the borax had been previously fused, it was at first supposed that this had altered its composition, but experimental proof was obtained that such was not the case. A complete analysis of the sample showed that it consisted of sodium triborntc. E’urther experiments were carried out to ascertain under what conditions the triborate is formed. I t was found that aqueous solutions of borax containing an excess of boric acid deposit crystals of sodium triborate.The above sample was the only abnormal one in a large number of samples of commercial borax examined, showing that the substitution of the triborate for the ordinary biborate occurs but seldom. w. P. s. Standardization of Permanganate Solution. F. Dupr6. (Zeits. f. nngew. Chem., 1904, xxv., 815.)-The author states that iron wire, ferrous ammonium sulphate, and oxalic acid are all unsatisfactoryfor this purpose when a high degree of accuracy is required. Treadwell’s electrolytic iron method is very reliable, but is tedious, and requires special apparatus, which in many technical laboratories is unavailable. The author finds that Volhard’s iodometric method is as accurate as Treadwell’s, and far more rapid. riceording to Volhard, the potassium perman- ganate should be recrystallized repeatedly to free it from perchlorate, but Dupre found that samples as purchased were already free from this impurity. To a solution containing 0.5 granime of potassium iodide in 1LO C.C. of water, 5 C.C. of pure hydrochloric acid are added, and 20 C.C. of the permsnganate solution are run in with constant stirring. Iodine is set free in accordance with the equation KMnO, + 5KI + 8HC1= 51 + 6KC1+ MnCl, + 4H,O, and is titrated directly with decinormal thiosulphate solution, using starch as indicator. The thiosulphate solution should be kept for at least a, week before using, in order to give time for all the carbonic acid present to react with the thiosulphate. When the whole of this carbonic acid has disappeared the solution will retain its strength indefinitely. A. If.

ISSN:0003-2654    

DOI:10.1039/AN9042900381

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE ANALYST. 385 APPARATUS. ‘‘ Spray ’’ Absorber. Romuald Nowicki. (Chem. Zeit., 1904, liv., 644.)-The apparatus has a double container, the two chambers of which may be filled with different absorbing liquids. The inlet tube reaches almost to the bottom of the vessel, and finishes with a jet bent upwards, and inserted in the end of a vertical spiral tube. From this jet, under the influence of suction, the gas is “sprayed” through the spiral, creating and carrying with it a current of the absorbent. The gas is thus constantly brought in contact with fresh solution, and a correspondingly increased efficiency is obtained. Made by Messrs. Rohrbeck’s SUCS., Vienna. H. A. T. New U-Tube. Romuald Nowicki. (Chem. Zed., 1904, lii., 622.)--In this form of U-tube the connecting-tubes are not attached to the outer, but to the inner, sides of the respective limbs.At the point of contact they are bent out at right angles, and there fused together. Owing to their lateral projection, the U-tube can be laid OD the balance-pan. The tube is considerably stiffened, and a series can be built up in much smaller space than with the usual form. H. A. T. Obtainable from W. J. Rohrbeck’s Nachf., Vienna. 1 2 3 New Pipette. Carl Meyer. (Chem. Zeit., 1904, lvi., 665.) -A new pipette, consisting of a graduated outer tube (Fig. 1) containing a glass rod, the lower end of which is ground into the outlet of the outer tube. Tube and rod are joined at the top by a closely-fitting piece of rubber tubing. With the rod raised, the pipette can be filled by suction at the lateral tube, and the desired quantity run out by slightly pressing the rubber tube, thereby lifting the rod.Obtainable from R. Kirchner and Co., Ilmenau. H. A. T. Laboratory Apparatus for Steam Distilla- tion. E. Pozzi-Escot. (BUZZ. SOC. Chim., 1904, 932; through Chem. Zeit. Rep., 1904, xix., 217.) -This apparatus consists of a double flask, the construction of which is obvious from the figure. The inner container is about 300 millimetres in length; the outer flask is of the usual 1-litre size. acids in fermented liquids. It is especially suitable for the determination of volatile H. A. T. A386 THE ANALYST. New Laboratory Apparatus. W. Pip. (Chevz. Zeit., 1904, lxx., 818.)- To avoid using various-sized rubber corks when filtering with flasks of different sizes - under reduced pressure, the author uses a stout " washer " or pierced disc of stout rubber.Placed on the neck of the flask, and the funnel loosely inserted in the central hole, the pressure caused by the partial vacuum in the flask is quite sufficient to insure an air- tight joint. For filtering excessively hygro- scopic substances a double funnel is suggested. The top of this funnel is enclosed, with the exception of a central aperture sufficiently large to admit of the passage of the filter-paper. Connected by a rubber cork to this is a separating funnel, fitted at the top with an ordinary drying tube. The liquid to be filtered is placed in the L-. -1_1_1_ 2 - L1_.__ _ 1 _ - 1 1 1 1 '1 ' I 1 m, I . _ I > separar;or, wmcn is men ciosea ~y me arying mme. ' m e apparatus is made by Messrs. Max Kaehler, of Martini, Berlin, W. H. A. T. Special Flask for the Preparation of Standard Solutions. A. Goske. (Chem. Zeit., 1904, lxviii., 795.)-The long neck of the litre flask is graduated in C.C. from 920 C.C. to 1,000 c.c., thus simpli- fying the dilution of slightly concentrated standard solutions. I t renders unnecessary the use of 8 separate vessel for the original preparation of the solution, or of measuring tubes, etc. The apparatus is made in 1, 2, and 5 litre sizes by Messrs. H. Goeckel, Berlin, W. H. A. T.

ISSN:0003-2654    

DOI:10.1039/AN9042900385

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE ANALYST. 387 H I G H C O U R T O F J U S T I C E . KING’S BENCH DIVISION. (From the ‘‘ Times ” of November 7, 1904.) (Before the LORD CHIEF JUSTICE OF ENGLAND, MR. JUSTICE KENNEDY, and MR. JUSTICE RIDLEY .) HULL v. HORSNELL. THIS was a case stated by Justices for the County of Sussex for the opinion of the Court on certain questions of law raised upon the hearing of an information against the appellant under the Food and Drugs Act, 1875, heard at Bexhill in April of this year. The information was preferred by the respondent, and charged that the appellant, James Hull, did on February 19, 1904, unlawfully and wilfully sell to the respondent “ a certain article of food-to wit, bottled peas-which to the knowledge of the said James Hull was mixed with a certain ingredient called sulphate of copper, which ingredient was injurious to health, contrary to the Sale of Food and Drugs Acts, 1875-1899, in such case made and provided.” The case stated that the respondent, an inspector under the Sale of Food and Drugs Act, purchased of the appellant, a greengrocer carrying on business at Bexhill, a bottle of preserved peas for the purpose of analysis.The respondent divided the peas so purchased into three parts, and sent one part to the Public Analyst, who gave his certificate as follows : “ I, the undersigned, Public Analyst for the administrative county of East Sussex, do hereby certify that I received from yourself on February 20 (per registered parcel post) a sample of bottled peas No. 14 for analysis (which then weighed about 4+ ounces), and have analysed the same, and declare the result of my analysis to be as follows : I am of opinion that the said sample is adulterated with sulphate of copper to the extent of at least 1.87 grains per pound.Observations.-The copper salt has doubtless been added to improve the colour of the peas.’’ The respondent proved that the bottle containing the peas bore the following label : “ English Garden Peas. Colour preserved with a small quantity of Sulphate of Copper. Preserved in Kent.-Petty, Wood and Go., London.” The Public Analyst was called for the prosecution, and he proved: (a) That sulphate of copper was a poisonous substance and injurious t o health ; ( b ) that sulphate of copper was used to preserve the colour of the peas ; ( c ) that he had never known anyone personally, or heard of anyone, injured by eating peas containing copper, but that he, the Public Analyst, suffered from colic if he ate coppered peas ; ( d ) that out of eight samples examined by him during the previous quarter seven contained copper.On behalf of the appellant it was contended that the information did not disclose any offence under the Sale of Food and Drugs Act, because it did not allege that the admixture of the ingredient called sulphate of copper rendered the article of food-namely, the peas-injurious to health, but lllerely that the ingredient itself was injurious to health, and that, therefore, the information was bad in law, and the appellant could not be convicted upon it. It’was also contended, on behalf of the appellant, that the certificate of the Public Analyst did not disclose any offence, and was insufficient, and did not comply with the requirements of the Sale of Food and Drugs Act.On behalf of the respondent it was contended that the information did disclose an offence under the Act ; that it is sufficient to constitute an offence under the latter part of Section 3 of the Sale of Food and Drugs Act, 1875, if the ingredient itself which is mixed with the article of food is injurious to health, and it is not necessary to show that the ingredient renders the article of food injurious to health. I t was also contended that the Analyst’s certificate was suficient, being in the form provided by the schedule to the Sale of Food and Drugs Act, and that the Finest English Marrowfat Peas.388 THE ANALYST. certificate need not disclose any offence.It -was contended, also, that the insufficiency (if any) was remedied by the Public Analyst being called as a witness to give evidence of the facts. The justices stated that they were of opinion that sulphate of copper, which was an ingredient in the peas, is injurious to health, and they therefore convicted the appellant, being of opinion that the ingredient necessarily rendered the whole article sold injurious to health. The questions for the opinion of the Court were : (1) Whether the information disclosed an offence under the Sale of Food and Drugs Act, and was valid in law ; (2) whether the Public Analyst's certificate was sufficient and valid in law; (3) whether the justices were right in law in convicting the appellant. Rlr.Horace Avory, K.C., and Mr. Bonsey appeared for the appellant ; Mr. Bosall, K.C. and Mr. Henriques for the respondent. The LORD CHIEF JUSTICE, in delivering judgment, said that if the justices had convicted the appellant of an offence under Section 3 of the Sale of Food and Drugs Act, 1875, on the groulid that the added ingredient-sulphate of copper-was injurious to health, :tnd not on the ground that the peas, by reason of the addition of the sulphate of copper, were rendered injurious to health, he was clearly of opinion that the conviction would be wrong. He had no doubt that in order to constitute an offence under the second part of Section 3 the article of food sold must be found to be injurious to health. Speaking for himself, he thought that the justices had, in fact, found the article itself-namely, the peas-was injurious to health. As, however, there might be some doubt as to whether they had so found, lie thought that the case ought to be sent back to them with instructions that if they had so found the conviction should stand, but that if they had found not that the peas were injurious to health, but that the sulphate of copper was, the conviction should not stand.Mr. Avory had taken a second point-namely, that the conviction could not stand because the certificate of the analyst was insufficient. His Lordship read the certificate and continued: I t was contended that at the end of the finding the analyst should have added the words " which rendered the article injurious to health," since the certificate, as it stood, did not show on the face of it that any offence had been committed. H e did not agree with that contention. The analyst could not know with what offence the person would be charged. I n his opinion, a certificate was sufficient if it wasone which was in accord- ance with the terms of the schedule, and set out the description of the goods sent for analysis, the weight and the other requirenients of the schedule. He was of opinion that the certificate given by the analyst in this case was sufficient. MR. JUSTICE KENNEDY and MR. JUSTICE RIDLEY concurred. INSTITUTE OF CHEMISTRY OF GREAT BRITAIN AND IRELAND. EXAMINATION IN BIOLOGICAL CHEMISTRY, OCTOBER 25 TO 28, 1904. THE following candidates passed : Fi%ZZozo .- Clark, Robert Macfarlane, B.Sc. (Glasgow ). Associates : Arnaud, Francis William Frederick ; Kinnersley, Henry Wulff' ; Riley, Louis John Eczekiel. Candidates for the Associateship : Handcock, Walter Augustus ; Henley, Francis Richard, MA. (Oxon.). The exaininer was Prof. Adrian John Brown, N.Sc. (Birmingham), F.I.C.

ISSN:0003-2654    

DOI:10.1039/AN9042900387

出版商:RSC    

年代:1904

数据来源: RSC