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JULY 1913. Vol. XXXVIII. No. 448. THE ANALYST. OBITUARY. M. A. ADAMS F.R.C.S. F.I.C. IT falls once more to the lot of the writer to give expression to his great sorrow at the loss of a dear friend and colleague a prominent member and past President of the Society of Public Analysts. Matthew Algernon Adams passed away 76 years of age on April 29 at Bearsted Kent. He studied medicine at Guy’s Hospital, hearing chemistry lectures by Odling and Taylor. After having been house-surgeon to the Public Dispensary in Leeds he settled soon after 1860 as a medical practitioner in Maidstone. He specialised in ophthalmic surgery in which he excelled and earned an almost international repute. Hard-working and well-read he had wide scientific interests with a predilection for chemistry.In 1874 while the Sale of Food and Drugs Bill was under Parliamentary discussion Adams worked for some time in the laboratory of J. A. Wanklyn and was in the same year appointed Public Analyst for the county of Kent. He held that position till 1911 when he was succeeded by his former assistant] then partner L. W. Stansell. He also was analyst for Rochester and Maidstone. He was one of the medical men who when the Food and Drugs Act compelled local authorities to appoint public analysts developed in an iatro-analytical era into chemists. A number of them-like Letheby Hassall Tidy Wanklyn Stevenson Hill, Adams and Cameron became distinguished both as sanitarians and as analysts. At that time the exercise of the small amount of knowledge available for food analysis could easily be added as an appanage to a medical practice.Delicate questions involving an accurate knowledge of the chemistry of food had not yet arisen and there was fair reason why appointing authorities should entrust to the doctors who to them were the apostles of all that was scientific the duty of controlling the food-supply. Chemistry and the processes carried on in laboratories are even now after a genera-tion impenetrable mysteries to local administrators. At that time as now the doctor to the popular mind represented the knowledge of nature from medicine to sstronomy from geology to sewage-treatment from sanitation to adulteration, Many of the medico-chemists-Adams among them-rendered splendid service and the now independent profession of chemistry owes them a deep debt of gratitude.In Germany the modern chemist developed from the apothecary; in England upon a less chemical but broader humanitarian medical basis. Adams was born in i836 in London 306 OBITUARY M. A . ADAMS Adams for many years regularly attended the meetings of the Society. His capacity for clear exposition at the meetings his sound common sense in the Council, his geniality and kindness in the Chair greatly endeared him to the members. An observation made by him in 1884 that cooked (not raw) apple-pulp contained a substance reacting with iodine like starch enabling the ready distinction of apple in mixtures with other fruits has been found exceedingly useful in the microscopical examination of jams. About 1880 and for some years afterwards an amount of controversy which now seems hardly intelligible raged round the composition and analysis of milk.Wanklyn had some years before stated upon somewhat slender data that milk, apart from a considerable variation in the fat percentage was of remarkably constant composition the amount of ( 6 solids-not-fat ” ranging from 9.0 to 9.3 per cent. While this statement had never met with acceptance by Continental chemists public analysts had adopted Wanklyn’s methods of milk analysis and his figures almost without criticism. The method adopted by Wanklyn for the separation of fatty and non-fahty constituents was inconceivably crude and consisted in the direct extraction of the hard horn-like and impervious masses of casein and sugar obtained by the evaporation of milk in small basins with a few successively applied portions of ether.Of course anyone now can see that the whole of the fat could not thus be extracted. Workers like Vieth then at the Aylesbury Dairy Company trained in other schools, had always insisted upon a subdivision of the solids by gypsum or other powdered mineral matter But no one had realised how widely the discrepancies of analysis of the same sample of milk could be in various otherwise competent hands until a celebrated milk case heard in Manchester in 1885 caused the appointment by the Society of a Milk Committee to investigate the matter. Portions of the same milk were distributed and analysed by the members of the Committee each one at first following his own laboratory method. The discrepancies were relatively enormous.While various proposed modifications were being investigated Adams’s mechanical genius solved the question in the simplest possible manner. By merely distributing a weighed quantity of milk over strips of blotting-paper and thus subdividing the solids over a very large surface the direct extraction of the fat became easy and complete. It is true that Adams at first overlooked the fact that all blotting-paper contains substances which partly under the influence of the action of the milk, become soluble in ether and thus add to the apparent percentage of fat-an error at once detected and corrected by Vieth. But we owe to Adams the simple solution of a problem which at that time was of urgent importance and it can truly be said that from the introduction of the Adams method accurate milk-analysis takes its date, and that it at once swept away all previously published results.It has become the standard method by which all other methods of fat-estimation in milk are judged and regulated. The observation in itself was a small one but it has affected each one of the fifty thousand milk analyses annually made by English and Scottish public analysts. Living in the midst of the Kentish hop industry Adams was greatly interested in the chemistry of the hop. He worked out a process for preserving new hops and preventing them from undergoing deteriorating changes which vastly affect thei PROCEEDINGS OF THE SOCIETY O F PUBLIC ANALYSTS 307 price. He also devised a process for the distinction of hop-bitter from quassia and other bitter substances in malt beverages, He was President of the Society of Public Analysts in 1889 and 1890 and a Fellow of the Institute of Chemistry and of other chemical and scientific bodies.To his activity as Medical Officer of Health and Sanitarian no detailed reference need be made in the ANALYST. His services to the Borough of Maidstone in the suppression of diphtheria and smallpox and at the time of the terrible outbreak of typhoid fever in 1897 secure him the lasting gratitude of his fellow-citizens. For many years I was in intimate and very frequent contact with him in London and at his home in Bearsted where in the middle of lovely Kentish scenery he had built himself a house on a hill affording a wide panoramic outlook. The kindest memories will ever connect him with many of my colleagues and myself who had deplored that as a result of a serious illness some nine years ago he had been compelled to forego attendance at our meetings. OTTO HEHNER

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DOI:10.1039/AN9133800305

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年代:1913

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PROCEEDINGS OF THE SOCIETY O F PUBLIC ANALYSTS 307 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE monthly meeting of the Society was held on Wednesday evening, June 4, in the Chemical Society’s Rooms, Burlington House. The President, Mr. L. Archbutt, F.I.C., occupied the chair. The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs.U. R. Evans, B.A., C. W. Birch, and H. W. Gill, B.Sc., A.I.C., were read for the second time ; and certificates in favour of Messrs. John Joseph Eastick, A.R.S.M., F.I.C., analytical and consulting chemist, 2, St. Dunstan’s Hill, London, E.C., and J. F. Millar, chemist to the Cawnpore Sugar Company, Ltd., Cawnpore, India, were read for the first time.Mr. F. S. Sinnatt was elected a member of the Society. The following papers were read : ‘‘ An Electro-chemical Indicator for Oxidisers,” by Eric K. Rideal, B.A., and Ulick R. Evans, B.A. ; “The Estimation of Tannin in Tea,” by Henry L. Smith, B.Sc., F.I.C. ; ‘‘ The Detection and Estimation of Nickel by means of a-Beneildioxime,” by F. W. Atack, M.Sc. ; ‘‘ The Analysis of Various East-Indian Tanned Hides,” by M. C. Lamb; ‘‘ A General Method for the Detection of Caramel,” by P. F. Thompson; and a ‘‘ Note on the Sterilisation of Rag Flock Samples,” by Lester Reed, F.I.C.

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DOI:10.1039/AN9133800307

出版商:RSC    

年代:1913

数据来源: RSC

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308 F. H. AND P. V. DUPRE: CONSTANT TEMPERATURE APPARATUS. BY F. H. AND P. V. DUPRG. (Read at the Meeting, May 7, 1913.) HAVING for some years past had occasion to carry out work which necessitated a very accurate regulation of temperature, in some cases for many hours at a time, and not having been able to find anything on the market which was entirely satisfactory, we have designed an apparatus which has proved extremely efficient.The object we set before ourselves was to design something that would give a wide range of temperatures, with a very high degree of accuracy, for any length of time required, and not requiring supervision. We also wished, if possible, to avoid the use of an inflammable liquid, and to obtain this large range of temperatures without any modification of the apparatus or alteration in the liquid with which it was filled. This object we think we may fairly claim to have attained.I n the first place, we will describe the construction of the apparatus and the principle of its action ; secondly, a description of our method of using it ; and, thirdly, what we consider to be its advantages and the degree of accuracy obtainable.The apparatus, which is based on the principle that the temperature of the steam given off by water, boiling under constant pressure, is constant, consists of a boiler, which is about one-third full of water, a reflux condenser, a water-jacketed pressure bulb, and a screw valve, marked A, B, C, D respectively in the figure. When the screw valve is shut, the whole apparatus is absolutely air-tight. A fusible metal safety plug is supplied.When the boiler is heated by a gas flame, or by any other suitable source of heat, the steam generated drives all the air from the boiler over into the pressure bulb, thus causing a definite pressure in the latter, depending on the total amount of air present originally in the whole apparatus, the steam being condensed and returned to the boiler.This pressure determines the temperature of the steam evolved in the boiler, and so long as sufficient heat is supplied to keep the water boiling withoutCONSTANT TEMPERATURE APPARATUS 309 producing more steam than can be dealt with by the condenser, the temperature remains practically constant. Within these limits the amount of heat supplied to the boiler has very little effect on the temperature, and as the type of condenser which we use can deal easily with the amount of steam produced in a two-gallon still by a gas burner consuming 20 cubic feet of gas per hour, it is obvious that a very large variation in the size of the gas flame employed is permissible." As the pressure in the bulb will obviously be affected by changes of temperature, the water supplied to the condenser is first passed through the jacket of the pressure bulb. As it is necessary for the temperature of this water to remain constant, it should be taken either from a large cistern, or, preferably, from the main direct. Method of Use.-The exact temperature required can readily be obtained as follows : When temperatures of above 100" C.are'required, the screw valve is opened so a8 to fill the apparatus with air at atmospheric pressure. The valve is then closed, the cooling water turned on, and the gas lighted. After a short time all the air in the boiler is driven over into the bulb, the relative volumes of boiler and bulb being SO arranged that this will give the maximum pressure, and consequently the maximum temperature, for which the apparatus is constructed. If this temperature is higher than that required, the valve is cautiously opened and air allowed to escape until the desired temperature is reached. The valve is then screwed down tightly, when the temperature will remain constant so long as the amount of heat supplied to the boiler is within the limits laid down above.Moreover, the apparatus may be allowed to cool, and provided that the vaIve is not opened, and the temperatureof the cooling water is unchanged, on applying heat again, the same temperature will be reached and maintained. If temperatures below 100" C.are required, the apparatus is exhausted to such a degree that a temperature lower than that which is actually required will be produced.The valve is then cautiously opened and air allowed to enter the apparatus until the required temperature is attained. The valve is then tightly closed, when the same conditions as previously described will obtain. If an ordinary high-pressure, water-jet pump is employed and the apparatcs exhausted when cold, a temperature of about 35" C. will be obtained. If lower temperatures than this are required, the apparatus can be further exhausted when the water is boiling, care being taken to have the water boiling as gently as possible so as to avoid any steam being sucked out of the apparatus; in this way a tempera- ture of about 27" C.will be obtained. We have made a number of experiments and find that, without taking any precautions to screen the apparatus from draughts, etc., or to regulate the gas- supply, the maximurn variation will be less than +0*05" C.however long the apparatus is going, or at whatever the temperature at which one is working, always provided that the temperature of the cooling water is unaltered. At temperatures of * As an experiment the amount of gas supplied t o the burner was measured : it was found to be a t the rate of 9-7 cubic feet per hour, the temperature of the apparatus being 71" C.The gas was turned down, the rate being then measured, and found to be 3.7 cubic feet per hour ; the temperature then fell to 70.85" C.310 F. H. AND P. v. D U P R ~ : 100" c. a variation of 1' C. in the temperature of the cooling water makes a difference of about 0.1' C. in the temperature of the apparatus ; at lower temperatures variations in the temperature of the cooling water make rather less difference than this, at higher temperatures rather more. With a regulated gas-supply, and with cooling water direct from the main, we have been able to keep the temperature constant for about an hour at a time, within +O.O0lo C.We believe it would be quite possible, by suitable modifications, to insure a variation of not more than this for longer periods.With the apparatus we have had made any temperature between 25O and 145' C. can be maintained. Higher temperatures than these can be obtained by making the apparatus stronger ; lower temperatures we have not experimented with.* Advantages.-(l) The avoidance of any inflammable liquid, or of one which might change its boiling-point, owing t o decomposition caused by prolonged heating.(2) The attainment of the whole range of temperatures with one apparatus, con- taining only one liquid, and with no other manipulations than those mentioned ebove. (3) Extreme regularity of temperature. (4) Automatic regulation of temperature, no supervision whatever being required when once the apparatus is properly going. (5) The temperature at which the apparatus has been set is reached very quickly. The water can be turned on, the gas lighted, and the bath left with bhe knowledge that at any time after, say, fifteen minutes a constant temperature will be reached.As the apparatus cannot possibly go higher than it is set for, there is no need to watch it while the temperature is rising.(6) If the bath has been going continually, and the temperature is the same at the beginning and at the end of any period, however long, it is certain that the temperature has remained constant during the whole of that period within the limits mentioned above. For example, if the temperature is right when leaving it in the evening, and is sfill right the next morning, there is no fear that the temperature may have varied during the interval.(8) As a com- paratively high temperature may be employed, the apparatus is but little affected by draughts, temporary cooling of any part, etc. (9) When a cold body is intro- duced into the apparatus, its temperature is very quickly raised owing to the large amount of heat given up by the condensed steam.(10) The apparatus cannot get out of order while out of use. (11) Constant temperatures are maintained for any length of time. (12) Alterations of room temperature or of barometric pressure have no influence on the apparatus. (13) No regulation of the heating flame is required unless extreme accuracy is necessary. (14) The temperature can be changed, and a new constant temperature obtained in a very short time.We have also devised a small piece of apparatus to facilitate the adjustment of the temperature. It is simply a means of estimating the quantity of air entering or leaving the apparatus, by causing it to pass through water, enabling the bubbles of air to be counted. The adjustment is a very delicate one, as a large number of bubbles are required to alter the temperature by 1' C.We are indebted to Messrs. Baird and Tatlock, of London, for assistance in the construction of this apparatus. * The exact form of the apparatus depends on the purpose for which i t is required ; the form shown in the figure is intended for heat test work. (7) There is no need of a stirring device.CONSTANT TEMPERATURE APPARATUS 311 DISCUSSION.Mr. HEHNER remarked that the arrangement, as shown, the design of which was rmst ingenious, appeared to be limited in its utility to the heating of small tubes, such as test-tubes. Mr. F. H. DUPRE said that, although the apparatus shown was made only for heating test-tubes, the boiler might be made spherical, with a compartment which could be opened, and within certain limits its size could be varied considerably.The advantage over the ordinary water-oven was that a temperature of, say, 130' C. could be maintained just as well as 100' C. could be in an ordinary water-oven that was boiling hard. Mr. W. T. BURGESS asked if the authors could give a little more information as to how the readings would be affected by any variation that might occur in the initial temperature of the cooling water, upon the constancy of which the efficiency of the apparatus must depend.Mr. DUPRE said that it was certainly necessary that the temperature at which the cooling water was admitted should be constant, and it was therefore desirable to draw it either from a very large cistern or, as they did, from the main. In tests which they had made, extending over periods of about three weeks, they had found the temperature of the water drawn from the main to vary only to the extent of about a hundredth of a degree during the day.Dr. STEVENS said that if the boiler could be made in the form of a jacketed pan, which could be kept at 130' to 140' C., it would probably be much more useful. It would seem, however, to be easier to maintain a constant temperature in a boiler of the shape shown than when the boiIer formed the jacket of a pan, since in the latter case the space to be kept at a constant temperature would be much larger. The variation in the ordinary jacketed pan would not be more than 0.5' C. either way with a gas regulator. Mr. DUPRE said that the difliculty in the case of a jacketed pan would be due to the pressure. At 145" C. the pressure would be between three and four atmo- spheres, while at 3 5 O C. it would be only about an inch, and in either case the apparatus would have to be very strong in order to avoid leakage at the joints. If the pan could be satisfactorily constructed, the temperature could probably be kept constant within 0.5' C. A spherical vessel of reasonable size would, of course, be easy to make. A cylindrical water-oven of a reasonable size could also be made.

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DOI:10.1039/AN9133800308

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年代:1913

数据来源: RSC

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312 HENRY L. SMITH THE DETERMINATION OF TANNIN IN TEA. BY HENRY L. SMITH, B.Sc., F.I.C. INVESTIGATION CARRIED OUT UNDER THE SOCIETY’S ANALYTICAL INVESTIGATION SCHEME. (Read at the Meeting, June 4, 1913.) CONSIDERABLE doubt has been thrown on the accuracy of the permanganate process of estimating tannins, as it depends on the assumption that only tannins are precipitated by the saline gelatin solution, The nature of the tannin in tea is not known with any certainty, and different permanganate equivalents have been used by various workers.Results are given sometimes in terms of gallotannic acid and sometimes in terms of oxalic acid, the latter being stated to have very nearly the same equivalent as quercitannic acid. Tea tannin resembles quercitannic acid rather than gallotannic acid in the readiness with which insoluble anhydrides are formed.The work described in this paper is an attempt to apply the cinchonine method as devised by A. C. Chapman (J. Inst. Brewing, 1907, 13, 646, and 1909, 15, 360) for the estimation of tannin in hops to the estimation of the tannin in tea. The method employed is substantially the same as that described by Chapman.I t depends on the complete precipitation of tannin by means of a saturated solution of cinchonine gulphate, the cinchonine tannate being weighed. Caffeine is also precipitated to some extent by tannins, and it was found necessary to remove this alkaloid before precipitating with cinchonine. If the caffeine is not removed, some is carried down with the cinchonine tannate, and cannot be removed by washing with more cinchonine sulphate solution, nor by digestion of the dried precipitate with chloroform.The filtrate from the cinchonine tannate always gave a colour and precipitate on the addition of ferric salts, but after washing with a half-saturated solution of cinchonine sulphate, further washings gave no such colour. This colour was not the typical bluish-black obtained with gallic acid, but was somewhat greenish.To ascertain what substance remained in solution which gave the colour, tea infusions were precipitated with lead acetate, and the precipitate collected and washed. I t was then suspended in water and decomposed by means of sulphuretted hydrogen and filtered. The filtrate was boiled to remove sulphuretted hydrogen, concentrated, and dialysed. But little tannin passes the dialyser.The liquid outside the dialyser was evaporated to dryness and extracted with dry ether. The residue after evaporating the ether was very small. From several experiments insufficient material was obtained to purify in order to determine the melting-point. Under the microscope crystals were seen that closely resembled gallic acid, crystallised from ether. A solution of the substance in water gave no precipitate with gelatin nor with cinchonine sulphate.With ferric chloride a bluish-black colour was obtained. The filtrate was concentrated and treated with a large volume of alcohol and again filtered. The Other tea infusions were treated with gelatin and filtered.THE DETERMINATIOX OF TANNIN IN TEA 313 alcohol was then distilled off and the residual liquid filtered.Lead acetate was then added, the lead compound collected and decomposed in the usual way with sulphuretted hydrogen. The filtrate from the lead sulphide was then evaporated to dryness and extracted with dry ether. The residue, after distilling off the ether, was evidently not a pure substance, and attempts at purification failed.The whole dissolved readily in water and in alcohol, and somewhat less readily in ether ; benzene dissolved nothing. Under the microscope crystals could be seen that differed from gallic acid and from the crystalline residue previously mentioned. Ferric salts gave a greenish colour, which changed to violet and then red on the addition of sodium bicarbonate.It reduced ammoniacal silver nitrate, but not Fehling's solution. With lead acetate it gave a light buff precipitate, but with gelatin and with cinchonine sulphate it gave no precipitate. The substance showed signs of melting at about 197' C., but did not completely melt at 220" C. In its chemical behaviour it resembled protocatechuic acid or some derivative of it. A very small quantity of a substance giving similar reactions was obtained from the filtrates from a number of quantitative experiments with cinchonine sulphate.Barium carbonate was added to the filtrate and the precipitated cinchonine and barium sulphate filtered off. The filtrate was concentrated to small bulk, made just acid with sulphuric acid and extracted with ether. On distilling off the ether the substance was left.Nothing resembling tannin, and giving a precipitate either with gelatin or with cinchonine sulphate was found in these filtrates. Cinchonine sulphate, therefore, appears to quantitatively precipitate the tannin of tea under proper conditions. The substances not precipitated, and which give colours with ferric chloride, are not tannins. Determination of Nitrogen in the Precipitated Cinchonine Tamate.-The nitrogen in a number of preparations of cinchonine tannate from tea was determined by combustion with copper oxide.I n some cases the substance was collected from several quantitative experiments, In others the substance was prepared on a larger scale, and, after washing, was pressed on a porous plate and finally dried at 100" C.to constant weight, The following results were obtained : Tea. Indian A Indian B Indian C Ceylon ... China A China B China C Weight of Substance. Grm. Percentage of Nitrogen. ... 0.3856 ... 445 ... 0.4143 ... 4.44 0.2979 ... 4.40 ... 0.2964 ... 4-29 0.6602 ... 4.29 ... 0-3975 ... 4.32 0-4353 ... 4.31 ... 0-3806 ... 4.33 0.6573 ... 4.37 ... 0.6197 ... 4.28 ... 0.6907 ...4-22 The average percentage of nitrogen is 4-32 in the cinchonine tannate. The This is also the figure The variations figure 4.3 has been used in. calculating the tannin in tea. adopted by Chapman in his analyses of cinchonine lupulo-tannate.314 HENRY L. SMITH: in the percentage of nitrogen may be due either to the presence of tannins of different molecular weight, or to the formation of anhydrides. Attempts were made to extract the tannin and prepare cinchonine tannate from it.Different results were obtained according to the method employed for extraction. The lead compound obtained by precipitating tea infusions with lead acetate was decomposed by means of sulphuretted hydrogen. The filtrate was heated to remove sulphuretted hydrogen and filtered when cold.Two methods were then employed : (1) The liquid was extracted with ethyl acetate and the ethyl acetate removed by distillation under reduced pressure. The residue was yellowish-brown, and dissolved readily in water. Cinchonine tannate prepared from this gave the following results : 0.5199 grm. gave 21.0 C.C. N at 11" C. and 758 mm. N=4*75 per cent. 0.4585 grin gave 18.6 C.C.N at 6-45" C. and 748 mm. N=4*74 per cent. (2) After boiling off the sulphuretted hydrogen the solution was dialysed for twelve hours, then concentrated and filtered. The cinchonine tannate from this gave the following results : 0.3015 grm. gave 10.6 C.C. N at 15" C. and 761 mm. N=4.08 per cent. 0.7021 grm. gave 24.7 C.C. N at 1 3 O C. and 747 mm. N = 4.04 per cent. In preparing both these specimens of tannin a, considerable amount of precipi- tate formed, which was removed by filtration. On keeping a solution a day anhydrides were precipitated.From these results alone it is not possible to state that different tannins exist in tea, as it is very possible that the methods of extraction caused changes in the nature of the tannin. Estiiitatioiz of Tamin by Means of Cinchonine Sulphate.-The decoctions were prepared by boiling 10 grms.of the tea in 800 C.C. water for half an hour, filtering hot, and washing the leaves with 200 C.C. boiling water. When cold, thevolume was adjusted to 1,000 C.C. Digestion at 100" C., and allowing the liquid to cool in contact with the leaves before filtering, gave low results. The decoction, on cooling, is always somewhat turbid, especially in teas of high tannin con- tent.But little actual precipitation occurs, they can, however, be filtered bright. This removes some tannin, as the particles causing the turbidity contain both tanninand caffeine. Fifty C.C. of the cold decoction were treated with four suc- cessive amounts of 30 C.C. of chloroform, which was found to be sufficient to remove practically all the caffeine.The liquid became clearer on removal of the caffeine. The liquid was then evaporated to about one-third its bulk, and 50 C.C. of a saturated solution of cinchonine sulphate added while still hot and clear. I t was allowed.to stand some hours, and then filtered through asbestos in a Gooch crucible. The prepared crucible was previously washed with a half-saturated solution of cinchonine sulphate and dried at 100" C.The precipitate was also washed with hslf- saturated cinchonine sulphate solution and thoroughly drained with suction. I t was found advisable to dry the precipitate over sulphuric acid first, and to save time a vacuum desiccator was used ; finally it was dried to constant weight at 100" C. If the damp precipitate was dried in the oven it fused, and it was difficult to get constant results, but if first partially dried over sulphuric acid fusion did not occur.Consistent results can be obtained by this method, as shown in the analyses of tannin in a few typical teas in the table.THE DETERMINATION OF TANNIN I N TEA 315 The cinchonine precipitate is assumed to contain 4.3 per cent.N, and as cinchonine contains 9-52 per cent. N, the precipitate will contain 45.1 per cent. cinchonine and 54.9 tannin, provided that it is anhydrous. The precipitate has been assumed to contain 55 per cent. of tannin, a8 the process is not of such accuracy as to warrant the use of the figure 54.9. In some cases the tannin has also been estimated by the permanganate method, Procter’s modification of Loewenthal’s process being employed.The results are calculated as oxalic acid. After detannating the decoction with gelatin and the acid salt solution, the filtrate gave no colour with ferric chloride ; but on carefully neutralising, a, greenish- black colour was obtained. I t will be noticed that the figures in terms of oxalic acid are always low.Whether this is due to the permanganate equivalent of the tannin being incorrect or some other reason, it is not possible to decide in the present state of our knowledge of the tannins of tea. Tea. Indian A ... Indian B ... Indian C ... Ceylon ... ... China A .. . China B ... China C ... Moisture. - 6.60 6-25 7.95 8-15 10.10 - Precipitate from 50 C.C. Decoction. Percentage of Tannin by Cinchonine.15.1 16.9 16.5 14.5 11.6 13.5 12.0 Percentage by I<Mn04 as Oxalic Acid. 13.9 15.8 - 12.4 9.1 - 9.0 DISCUSSION. Mr. A. CHASTON CHAPMAN said that in the case of the tannin of hops precipitation with quinine was not nearly so satisfactory as precipitation with cinchonine, the cinchonine precipitate being more insoluble and the results more concordant. He was interested to see that the cinchonine precipitate obtained with tea tannin was so similar in composition t o that yielded by hop tannin, because in some respects these two tannins appeared to differ rather widely.He also had found, in the case of hop tannin, that something always came through the filter which gave a coloration with ferric chloride, but he had demonstrated that this was not tannin.As to the deter-316 F. W. ATACK: THE DETECTION AND ESTIMATION OF mination of nitrogen, while cinchonine itself yielded all its nitrogen readily by the Kjeldahl process, the results in the case of this cinchonine tannate were always low ; and even by theDumas process it was difficult to get all the nitrogen unless cuprous chloride were used. The difficulty of determining tannin lay not so much in the actual estimation of the tannin, as in getting it into solution without decomposition. He should have expected Indian tea, judging from its flavour, to contain more tannin than Mr.Smith had found to be the case. Mr. CHASTON CHAPMAN said that the object of his work on the determination of tannin in hops had been to ascertain whether the proportion of tannin was really of any practical consequence. I t used to be supposed that the higher the proportion of tannin the greater was the value of the hops for brewing purposes, and that the tannin diminished on storage ; but on investigation it was found that there was no connection between the proportion of tannin and the brewing value of the hops, and that the tannin did not diminish, but remained practically constant.He had made a few experiments on the application of the method to tannin materials, and the results appeared to be satisfactory, but he had not gone very far in that direction. Mr. E. R. BOLTON asked whether Mr. Smith had determined the theine in any of these samples. I t had been suggested that the ratio of tannin to theine was an important factor in the valuation of tea. Mr. SMITH agreed that the ratio of caffeine to tannin was more important than the actual percentage of tannin. He had not applied the method to any other material than tea, with the exception of one experiment made with coffee, which was negative in value.

ISSN:0003-2654    

DOI:10.1039/AN9133800312

出版商:RSC    

年代:1913

数据来源: RSC

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316 F. W. ATACK: THE DETECTION AND ESTIMATION OF THE DETECTION AND ESTIMATION OF NICKEL BY MEANS OF a-BENZILDIOXIME. BY FREDERICK WILLIAM ATACK, M.Sc. TECH., B.Sc., A.I.C. (Read at the iweeting, June 4, 1913.) THE use of dimethylglyoxime as a reagent for nickel was first suggested by Tschugaeff (Bey., 1905, 38, 2520). The reagent was applied by Kraut (Zeitsch. angew. Chem., 1906, 19, 1793) for the gravimetric determination of small amounts of nickel.I t s general application for the gravimetric estimation of nickel is due to 0. Brunck (Zeitsch. angew. Chem., 1907, 20, 834 and 1844), who gave details of the estimation of nickel in presence of cobalt, iron, manganese, chromium, and zinc, and later (Stahl u. Eisen, 1908, 28, 331j applied the reagent to the deter- mination of nickel in nickel steel and in chromium nickel steel.The method of weighing the nickel dioxime precipitate on filter-papers was used by A. Iwanicki (ibid., 1908, 28, 1546; 1909, 29, 1154). H. Wdowiszewski (ibid., 1908, 28, 960; 1909, 29, 358) and F. Ibbotson (Chem. News, 1911, 104, 224) have suggested the ignition of the nickel precipitate. In his ‘‘ Report on Gravimetric Methods for the Determination of Nickel in Nickel Steel” (ANALYST, 1910, 35, 97), E.L. Rhead found the dimethylglyoxime method to be the most convenient one available for theNICKEL BY MEANS OF U-BENZILDIOXIME 317 estimation of nickel in presence of iron. La. V. W. Spring (ANALYST, 1911, 36, 524) recommends the dimethylglyoxime reagent for the determination of nickel in nickel- zinc alloys and in German silver.A new reagent for nickel is now proposed which has decided advantages over the dimethylglyoxime reagent-viz., a-benzildioxime. This reagent is available for the detection and estimation of nickel, giving an intense red precipitate which consists of the nickel salt, C,8H,,N,0,Ni, one hydrogen atom in each of two molecules of the dioxime being replaced by metal.This compound was described by Tschugaeff (Zeitsch. anorg. Chem., 1905, 46, 144), but the reaction does not appear to have been applied as a qualitative test or for the gravimetric determination of nickel. QUALITATIVE APPLICATION OF THE REAGENT. An alcoholic solution of a-benzildioxime has been found to constitute a very delicate test for the presence of nickel, being an even more characteristic reagent for nickel than the dimethylglyoxime reagent suggested by Tschugaeff. For qualitative purposes a 0.02 per cent.solution of the reagent is dissolved in alcohol to which 5 per cent. of dilute ammonia solution has been added. This solution is quite stable, and has been kept for several months. The reagent can also be used in acetone solution.In either case the solution to be tested is made ammoniacal before addition of the reagent. The new reagent appears to have several distinct advantages over the dimethylglyoxime reagent. Several series of comparative tests have led to the following conclusions : Nickel only Present.-It was found possible to detect immediately less than 1 part of nickel in 2,000,000 parts of water, using a volume of 5 c.c., corresponding to 0.002 mgrm.of nickel, by means of a-benzildioxime, which gave a copious pre- cipitate, whereas it was necessary to allow a corresponding test with dimethyl- glyoxime to stand twenty-four hours before the coloration appeared. In general it may be remarked that the new reagent invariably gives an almost immediate reaction if sufficient nickel is present.The rapidity with which the reaction occurs with a-benzildioxime admits of the reagent being applied conveniently as a ring-test. The results with both dimet hy lgl yoxime and a- benzildioxime (a-diphen ylgly oxime) are seriously affected by the presence of large amounts of nitrates. I n Presence of Cobalt.-Whereas freshly prepared ammoniacal cobalt solutions (free from nickel) containing 1 part of cobalt in 50,000 parts of water give an intense reddish-violet coloration and pinkish meniscus with dimethylglyoxime, the same solution was found to give only a faint yellow coloration with the a-benzildioxime reagent.I n presence of 100 times the amount of cobalt the direct detection of nickel in ammoniacal solution of concentration 1 of nickel in 1,000,000 of water is easy by means of the new reagent, a copious precipitate being obtained almost immediately from a total volume of 10 C.C.The reaction is much more characteristic than with dimethylglyoxime, with which no precipitate was obtained after standing three days, although the colour was then certainly different, though not distinctively so, from a blank containing the same amount of cobalt.The solution efl'ect of the presence of cobalt on the nickel dimethylglyoxime reaction was mentioned in Brunck's318 F. W. ATACK: THE DETECTION AND ESTIMATION OF original paper. Larger amounts of cobalt must be oxidised by shaking in ammon- iacal solution before carrying out the test. In Presence of I~on.-Slavik (Chewt. Zeit., 1910, 34, 648) has shown that ferrous salts give an intense pink colour with dimethylglyoxime in ammoniacal tartaric or, preferably, citric acid solution-a method which the present writer has found very satisfactory for the rapid detection of small amounts of iron in presence of titanous and similar salts.Hence it is necessary to oxidise ferrous salts before testing for nickel with the dimethylglyoxime reagent. If occasion should arise for the detection of nickel in presence of ferrous salts, the a-benzildioxime reagent may be applied, as the violet coloration produced with ferrous salts does not mask the nickel reaction.In presence of ferric salts the reagent has been applied with success for the direct detection of nickel in presence of over 1,000 times the amount of iron, prefer- ably in ammoniacal citric acid solution.Thus 1 part of nickel and 1,200 parts of iron in 1,000,000 parts of water gave an immediate coloration and a much more voluminous precipitate than the dimethylglyoxime reagent, the colour of which only appeared after standing three hours. The reaction with a-benzildioxime does not appear to be interfered with by the presence of large amounts of silver, magnesium, chromium, or manganese.The presence of large amounts of zinc has been found to prevent the formation of the nickel coloration with dimethylglyoxime, whereas the a-benzildioxime test is un- affected, ti copious precipitate being obtained on standing a short time. QUANTITATIVE APPLICATION OF THE REAUENT. a-Benzildioxime forms a convenient reagent for the estimation of amounts less than 0.025 grm.of nickel. Owing to the rather low solubility of the reagent in alcohol, and the voluminous character of the precipitate, it is not advisable to have a larger amount of nickel present. A slight excess of a warm solution of the reagent in alcohol, to which ammonia has been added, is added, with stirring, to the ammoniacal nickel solution, and the whole heated on the water-bath for a few moments to coagulate the precipitate.Quantitative precipitation is complete after one minute, whereas in using the dimethylglyoxime reagent precipitation has often been found to have been incomplete after standing for an hour in a warm place. The liquid is filtered at the pump through a Gooch crucible or counterpoised filter- papers, washed with warm 50 per cent.alcohol, then with hot water, and finally dried at 110' C. The precipitate contains 10.93 per cent. nickel, and is hence very suitable for the determination of very small quantities of nickel. On washing with hot water the precipitate has no tendency to pass through the filter-paper, as is the case with the dimethylglyoxime precipitate ( c j .F. Ibbotson, Chm. News, 1911, 104, 224). The compound is much less soluble in warm alcohol-water mixtures than that from dimethylglyoxime, whose solubility in alcohol- water mixtures was men- tioned by Brunck (Eoc. cit.). Precipitation may also be effected with an acetone solution of the reagent, in which it is much more soluble. The following are typical results obtained by the a-benzildioxime method, the standard solutions being made from recrystallised nickel ammonium sulphateNICKEL BY MEANS OF a-BESZILDIOXIME 319 (Kahlbaum), which had been analysed by gravimetric methods, and found to be pure : Nickel Present.Grm. 1. 0.02748 2. 0,02269 3. 0.01645 4. 0.01645 5. 0.00480 6. 0,01535 Nickel Dioxime Precipitate. Grin. ... 0.2524 ... ... 0-2072 ...... 0.1510 ... ... 0.1502 ... ... 0,0442 ... ... 0*1408 . . . Nickel Found. Grm. 0,02758 0.02266 0.01650 0.01642 0-00481 0.01 539 Nos. 1 and 2 were weighed on asbestos in a Gooch crucible, Nos. 3 to 5 on counterpoised filter-papers, and No. 6 was precipitated by an acetone solution of the reagent. As the use of counterpoised filter-papers is often adversely criticised, it was of interest to investigate whether weighing in this manner was to be considered accurate in this case.The filter-papers were 7 cm. hydrochloric acid washed Schleicher-Schull papers, and these were subjected to identical treatment during the experiment with regard to washing, etc. In several of the above cases the pre- cipitate was detached from the filter-paper into a tared weighing-bottle, a process which is much more easily accomplished in the case of the a-benzildioxime pre- cipitate than that from dimethylglyoxime, only 0.2 to 0.4 mgrm.of the precipitate remaining on the paper. On reheating the filter-paper and weighing-bottle to 110" C., the total weight of the precipitate was not changed appreciably in any case, even after the temperature had been raised to 120° C.Exposure of the precipitate for half an hour in the balance-case showed that the precipitate does not absorb moisture to any appreciable extent. The method of weighing on counterpoised filter-papers is therefore available in this case. The method is affected by the presence of nitrates, which must therefore be removed by evaporation with sulphuric acid before the addition of the reagent.Ignition of the precipitate failed to yield satisfactory results, although care was taken to avoid loss of nickel by volatilisation of the compound as far as was possible. Possibly this is explained by the retention of small amounts of carbon, even though ammonium nitrate was added before the final ignition. P. Bogolubow (Stahl u. Eisen, 1910,30, p. 458) states that Wdowiszewski's method of igniting the dimethyl- glyoxime precipitate leaves carbon in the nickel oxide.In Presence of Cobalt.-The method is available in presence of cobalt, precipita- tion being effected in ammoniacal solution. Owing to the formation of a soluble cobalt salt of the dioxime, excess of the reagent must be added, the precipitate being washed until the filtrate is colourless.The following results were obtained : Nickel Present. Cobalt Present. Nickel Found. Grm. Grm . Grm. 1. 0.00658 ... 0.02 ... 0.00661 2. 0.00480 ... 0.04 ... 0.00483 3. 0.01645 ... 0-04 ... 0.01648 4. 0.01134 ... 0.02 ... 0*01140 I n No. 3 an acetone solution of the reagent was used.320 F. W. ATACK: THE DETECTION AND ESTIMATION OF In Presence of Iron.-Nickel can be estimated in presence of ferric salts in ammoniacal solution by keeping the iron in solution by Rochelle salt or, preferably, sodium citrate.A slight excess of the alcoholic solution of the reagent is added. The following results were obtained : Nickel Present. Iron Present. Nickel Found. Grm. Grm. Grm. 1. 0.01135 ... 0.14 .I. 0*01130 2. 0.00567 ... 0.03 ... 0.00565 3. 0.01099 ...0.07 ... 0~01102 The method is therefore available for the estimation of nickel in nickel steels. In Presence of Manganese.-Precipitation is effected by a fairly large excess of the alcoholic reagent in slightly acetic acid solution. Satisfactory results were obtained. In Presence 01 Zinc or Magnesium-The zinc or magnesium is kept in solution by addition of a large amount of ammonium chloride, precipitation being effected in ammoniacal solution.The results showed that neither zinc nor magnesium interfere with the precipitation, and nickel may be estimated by a-benzildioxime in presence of these metals. In Presence of Chromium.-Precipitation is effected in dilute ammoniacal solution in presence of tartaric acid, when the nickel present is precipitated quantitatively.The further application of the method to the analysis of nickel alloys is at present being examined. Whereas small amounts of copper do not interfere with the method, larger amounts must be precipitated before addition of the reagent. In conclusion, the author desires to express his indebtedness to Professor Knecht for the facilities afforded for the carrying out of the work.CHEXICAL DEPARTMENT, FACULTY OF TECHNOLOGY, UNIVERSITY OF MAKCKESTER. DISCUSSION. Mr. E. R. BOLTON said that nowadays the question of the presence in fats of traces of nickel, palladium, and other metals, used as catalysts, was of considerable importance in dealing with hydrogenised or hardened fats. He had used the diacetyldioxime method quite successfully, but had found that, when the quantity of metal present was very small, the colour was fugitive, returning, however, subse- quently.With diacetyldioxime, nickel could be separated from palladium, the palladinm being filtered off from an acid solution, which was then made alkaline with ammonia, precipitating the nickel. H e should be glad if the author would say where a-benzildioxime was to be obtained, as it was not included in the ordinary catalogues.The PRESIDENT said that he used the dimethylglyoxime method frequently, especially for the determination of nickel in copper, and had found it very satis- factory. In that case the nickel was precipitated from a solution slightly acid with acetic acid, whereas, in the case of a-benzildioxime, he understood that the solution was ammoniacal.From what Mr. Atack had said, it appeared that the a-benzil-NICKEL BY MEANS OF U-BENZILDIOXIME 321 dioxime method was the more delicate, and gave a sharper separation between nickel and cobalt. Mr. ATACK said that the subject of hardened oils was now under investigation, but embraced some points which were rather troublesome. I n a paper by Bomer (Zeitsch.Untersuch. Nahr. G ~ I ~ s s ~ z . , 1912, 24, 104) it was said to have been found by Prall that certain fats gave the nickel reaction with dimethylglyoxime before any nickel had been added, but no details were given, and he (Mr. Atack) had not been able to confirm that, nor had he met with any case in which a hardened fat did not give the reaction with a-benzildioxime.He had not been aware of the process for the separation of palladium from nickel by dimethylglyoxime, though he under- stood that a process had been published by Wunder and Thiiringer (Zeitsch. anal. Chem., 1913, 52, 101) for the separation of palladium from copper and iron, using this reagent. I n the case of a-benzildioxime the palladium compound appeared to decompose rapidly, $specially in the presence of light, but that point also was under investigation. a-Benzildioxime would probably be purchasable in the near future at cheaper rates than dimethylglyoxime, but even now it was quite easily prepared by boiling 10 grrns. benzil (not necessarily pure) with 8 to 10 grms. of hydroxylamine hydrochloride in methyl alcohol solution. After boiling for three hours the precipi- tate is filtered off, dried, washed with hot water, and then a small amount of 50 per cent. alcohol, and dried, when it consists of pure a-benzildioxime (m.-pt. 237' C.). A further yield can be obtained by boiling the filtrate with hydroxylamine hydro- chloride. He had tried precipitation from an acetic acid solution in the case of manganese, but care was necessary, or the a-benzildioxirne would change into the ,8 variety, which did not give the nickel reaction. Probably in the case of copper an acetic acid solution would have to be used, unless the copper were first separated by means of sulphuretted hydrogen.

ISSN:0003-2654    

DOI:10.1039/AN9133800316

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

NICKEL BY MEANS OF U-BENZILDIOXIME 321 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Detection of Aloes in Extracts of Drugs containing Oxymethylanthra- quinones. G. Mossler. (Pharm. Post., 1913, 46,313-315, 325-327 ; through Chem. Zentralbl., 1913, I., 1842-1843.)-The alcoholic extract is evaporated to expel the alcohol, the residue taken up with water, and the liquid filtered.The filtrate (100 c.c.) is heated for thirty minutes on ths water-bath with 5 C.C. of 10 per cent. sulphuric acid, the sulphuric acid precipitated with the exact amount of barium hydroxide solution, and the filtrate from the barium precipitate concentrated to 100 C.C. and clarified with lead acetate solution, care being taken to avoid a large excess. Ten C.C. of the solution are next filtered, and after removal of lead by means of sodium sulphate solution or dilute sulphuric acid, the filtrate is divided into two parts, One of these is shaken with 4 to 5 C.C.of benzene, and the benzene extract322 ABSTRACTS OF CHEMICAL PAPERS shaken with dilute ammonia solution. If the foreign oxymethylanthraquinones have been completely precipitated, the aqueous layer should not show more than a light rose colour, whilst a yellow coloration of the benzene layer indicates aloes.If, how- ever, the aqueous layer is distinctly red, the bulk of the original solution must again be treated with lead acetate. When the precipitation has thus been shown to be complete, the other portion of the filtrate is treated with an excess of bromine water, which, in the presence of rtloin, produces an immediate flocculent precipitate.The main solution is now freed from lead, and the filtrate tested by the reactions of Schouteten and Hirschsohn. I n the former 10 C.C. of the filtrate are gently heated and Rhaken with 2 to 3 grms. of borax and allowed to stand for fifteen minutes, when, in the presence of aloes, a green fluorescence appears.I n Hirschsohn’s test 10 C.C. of the solution are heated with 1 drop of copper sulphate solution and 1 drop of hydrogen peroxide. I n the presence of aloes a red coloration which becomes intensified on standing is obtained, whilst samples free from aloes become orange-red and do not alter on standing. I n this way it is possible to detect 0.2 grm. of aloes extract in 5 grms.of a mixture of extracts of rhubarb, frangula, and cascara sagrada. For the identification of the different oxymethylanthraquinone drugs the alcoholic extract is brought to a strength of 50 per cent. of alcohol and filtered. The filtrate is boiled for thirty minutes beneath a reflux condenser with about 5 per cent. of sulphuric acid, and then cooled and filtered, the alcohol evaporated from the filtrate (with frequent additions of water), and the precipitated oxym e t hylan t hraquinone s separated from the liquid, any aloin remaining in solution.The precipitate is washed until free from acid, dried and boiled with benzene, and the benzene extract shaken with 10 per cent. sodium carbonate solution, and then with dilute sodium hydroxide solution.The two alkaline extracts are separately acidified with hydrochloric acid, each shaken with 20 C.C. of benzene, and 4 to 5 C.C. of the benzene extracts evapor- ated. The residues are heated with 3 to 4 drops of acetic acid, and the solutions transferred to glass slips and examined, after thirty minutes, in polarised light. The crystals thus obtained from rhubarb, cascara sagrada, senna, etc., show pronounced differences, as is also the case with the crystals obtained by sublimation.C. A. M. New Reaction for the Detection of Aniline Dyestuffs [Magenta] in Foods, and especially in Wines. P. Malvezin. (Ann. Chinz. anal. appZ., 1913, 18, 193.)- Methanal hydrosulphite, CH,OH.SO,H, obtained by passing sulphur dioxide into 40 per cent. formaldehyde solution, is coloured violet by a very dilute solution of magenta, the reaction being rendered more sensitive by warming.The wine to be tested is decolourised with animal charcoal, and 2 to 3 C.C. of the filtrate are shaken in a test- tube with an equal volume of the reagent, heat being applied if only a faint violet coloration is obtained. Under the same conditions wine free from aniline dyestuffs gives a faint rose coloration.C. A. M. Estimation of Water in Cheese. Utz. (Zcitsch. angew. Chem, , 1913,26, 271- 273.)-Results of numerous estimations of water in cheese by distilling the sample with petroleum and measuring the volume of water in the distillate, show that thisFOOD AND DRUGS ANALYSIS 323 method is trustworthy. portion of ordimry paraffin oil which boils below 150" C.(cf. ANALYST, 1913, 146). w. P. s. It is recommended that the petroleum used should be that Sudan Dura. (Bull. Imp. Inst., 1913, 11, 33-4G.)-Dura, or L( dari," is already imported into the United Kingdom, where it is chiefly used as poultry food, and generally fetches prices similar to those paid for maize. A sample of the grain previously freed from dirt had the following composition : Moisture, 8.45 ; crude proteins, 13.06 (true proteins, 12.98 ; other nitrogenous substances: 0.08) ; fat, 3-30; total carbohydrates, 72.4; starch, 62-66 ; fibre, 1.03 ; ash, 1.71 per cent.; food units, 113.3; nutrient ratio, 1 : 6.1. No alkaloids or cyanogenetic glucosides were found, H. F. E. H. Modified Babcock Test for Fat in Sweetened Ice Cream.J. 0. Halverson. (J. Ind. and Eng. Chem., 1913, 5, 403-409.)-The Babcock test is not applicable to sweetened dairy products on account of the charring action on the sugar. It is noticeable that an appreciable interval of time elapses on adding sulphuric acid slowly before action on the sugar commences, and the modification suggested consists in draining off this acid sugar solution by using a special bottle fitted with a emall glass stopcock (1 mm.bore) on one side of a 6.5 inch 25 per cent. cream test-bottle. To a volume of cream (17-6 c.c.) is added 7 to 10 C.C. of ordinary sulphuric acid in 3 C.C. portions. When the colour reaches an amber brown, 2 to 3 C.C. of cold water are added, with shaking to check the action. The whole is then centrifuged for five minutes, and then hot water is added nearly up to the neck, followed by a further two minutes centrifuging. The acid sugar solution is now drained off, and acid again added (about 8 or 10 c.c.) till a coffee-black colour is reached.Hot water is then added up to the neck, and the whole again centrifuged two minutes. No further draining is necessary at this stage, and the fat is run into the neck with hot water, centrifuged one minute, and the reading taken.Very careful sampling of the ice cream is required in order to obtain consistent results. A number of results are recorded in comparison with the Rose-Gottlieb method, the modified Babcock test showing on the average results 0-6 per cent. low. H. F. E. H. '' Cheyi " Seed. (Bull. Imp. Inst., 1913, 11, G2-65.)--The seed is derived from PoZygaZa butyracea, a herbaceous plant common in tropical West Africa.The yield of fat 100" c. is 38 per cent., having the following constants :' M.-pt., 36" C. ; sp. gr., i5qo-e: = 0.866. Acid value, 1-24 ; saponification value, 251.0. Iodine value, per cent., 52.5 ; Titer test, 37.85" C. The stems of the plant yield a fibre considered by experts to be equal in value to fine Bombay hemp, and resembles Sunn hemp of similar appearance.Hehner value, per cent., 85.6; Reichert-Meissl value, 45.6. H. F. E. H. Oil Seeds from the Anglo-Egyptian Sudan. (BUZZ. Imp. Inst., 1913, 11, 56-62.)-Senat seed (otherwise '' hameid," '' fugus," '' ajurr," and '' tibish ") is324 ABSTRACTS OF CHEMICAL PAPERS derived from various cultivated varieties of Cucumis chate, which is probably the wild type of the cultivated melon.All the samples yield a pale yellow liquid oil, free from smell or unpleasant taste. Six samples were examined, with the following results, to which are added for comparison the figures for oils from other cucur- Yield per cent. ... Sp. gr. at C. Acid value* ... Saponification value* Iodine value per cent.t ...... 15-5" 5.5" Titer test. +' ... 1. 2. 3. 4. 36.5, 31.0 29-5 31.7 - 0.92: 0.923 - 1.0 - - 0.7 192.0 190-5 189.3 189.2 117.0 121.3 117-0 124.0 30.3" C. - - - I 5. 6 . 30-2 0.925 0.7 187.0 128.5 38.4 - - - - 43.8 - - 193.3 101.5 36" C. 40.8 - - 189.7 118.0 32" C. * Mgrms. of potassium hydroxide per grm. of fat. t 3lethod not described. 5 Solidifying-point of fatty acids.I n the case of No. 1 the Hehner value was 96.6, the percentage of unsaponifiable matter 0.7, and the Reichert-Meissl value nil. The senat husks have only a very low feeding value, and contain much fibre and mineral matter, but their high ash (17 per cent.) contains 43 per cent. of potash (K,O), which should render them useful as a manure. hard, ,bright yellow fat, with a faint, slightly unpleasant odour, having the following constants : Sp.gr. at 99" c. = 0.867 ; acid value, 9.3 ; saponification value, 245.2 ; iodine value per cent., Snlvadore persica seeds yield 44 per cent. of 5.9; Titer test, 30.4" C. (approx.); m.-pt., 38" C. H. F. E. H. Table of Caloulated Dry Substance of Milk by the Fleischmann Formula. R. Pfister and W. Leuze. (Jfilc722oirtschaf tl.Zentralbl., 1913, 42, 97, 134, 169, 196 ; through Chem. Zentralbl., 1913, I., 1728.)-The values are calculated from the formula- T= 1.2 f + 2.665 in which T is the total solids, and f the fat-content, both as percentages, and s the density at 15" C. The values of T may be read off directly from the table (published in the original journal) for values of f between 0.10 and 6.00, rising by 0.05, and for s from 1.0190 to 1.0400, rising by 0.0001.0. E. M.FOOD AND DRUGS ANALYSIS 325 Preservation of Milk Samples for Analysis. G. Deniges. (Ann. C h k . anal. appl., 1913, 18, 189-192.)-A solution of 50 grms. of phenol in 10 C.C. of 95 per cent. alcohol has proved more satisfactory than any of the other antiseptic agents used for the preservation of milk samples. The addition of 1 C.C.of the solution to 100 C.C. of milk keeps the sample indefinitely, and does not affect the estimation of the acidity, lactose, fat, casein, ash, or extract. A sample of milk thus preserved gave exactly the same analytical results after ten years as at first. C. A. M. Alteration of Milk treated with Potassium Diehromate. G. Hinard. (Ann.FalsiJic., 1913, 6, 233-237.)-Successive analyses, at intervals of a few weeks during a period of six months of a sample of milk which had been treated with potassium dichromate (0.98 grm. per litre) showed that the composition of the milk changed gradually, and that dichromate cannot be relied upon as a preservative of milk samples. In six months the total solids decreased to the extent of 10 grms.per litre, the solids-not-fat decreasing to about the same extent whilst the quantity of fat remained constant. The lactose varied considerably in quantity during the period, but at the end had diminished by 14 grms. per litre ; the quantity of casein also decreased, whilst the acidity, expressed as lactic acid, increased from 2.3 to 6.6 grms. per litre. w. P.s. Peroxydase Reaetion of Milk. (Influenee of Preservatives, ete.) T. Jona. (Arch. Pharmacol. sperim., 1913, 15, 122-130 ; through Chem. Zentralbl., 1913, I., 1790-1792.)-Whilst the presence in milk of the usual preservative substances does not interfere with the peroxydase reaction, in certain cases the presence of the preservatives lowers the temperature at which the milk ceases to give the reaction when heated; for instance, milk containing salicylic acid or mercuric chlorides no longer gives the reaction when heated to about 69" C.As regards the estimation of the age of milk by means of the peroxydase reaction, the author finds that, although there'is some relation between the age of milk (and its acidity) and its power of giving the reaction, definite conclusions cannot be arrived at from the indications yielded by the test.The addition of acetic or citric acid prevents the reaction with p-phenylenediamine, but the reaction with guaiacum is not affected ; mineral acids and oxalic acid inhibit the reaction with both reagents, whilst the natural acidity of milk interferes to a less extent. With respect to the reaction mentioned by Gaucher (ANALYST, 1908, 33, 237), it was found that a mixture of boiled milk with 40per cent.of raw milk behaved like raw milk, as it no longer decolourises hsmatin. Raw milk, containing 0.2 per cent. of formalin at once decolourises hEmatin ; milk containing traces of hydrogen sulphide behaves in the same way, but boiled milk to which hydrogen peroxide has been added does not decolourise the reagent.The presence of potassium dichromate or mercuric chloride interferes with the reaction. w. P. s. Estimation of Phenols in Creolins. A. J. J. Vandevelde. (Bzcll. SOC. Chirn. Belg., 1913, 27, 128-129.)-Creolins are mixtures of hydrocarbons with alkali salts of phenolic bodies. The disinfectant value of the mixture can only be deter-326 ABSTRACTS OF CHEMICAL PAPERS mined satisfactorily by bacteriological methods, but a determination of the total phenols is generally required.For this purpose, having found that certain of the hydrocarbons of creolin are not completely volatile with steam, the author prefers to acidify the mixture and to distil the phenols. Two hundred and fifty grms. of the creolin are treated with 500 C.C. of water and sufficient sulphuric acid to impart a distinctly acid reaction ; the whole is placed in a separating funnel with 100 C.C.of benzene, and allowed to remain at rest for twenty-four hours. By the aid of the benzene the separation of the aqueous layer is easily effected, and the oily layer is then submitted to a simple distillation, collecting all the products distilling below 230' to 240" C.The distillate then contains the phenol, oresols, a portion of the more volatile hydrocarbons, and the added benzene. It is shaken three times in suc- cession with quantities of 50 C.C. each of a 10 per cent. solution of sodium hydroxide. The aqueous portion, containing all the phenolic bodies, is separated and acidified in a graduated tube. The quantity of phenols may be ascertained approximately by dividing the volume of the layer by the mean density 1.055, or it may be separated and weighed.The results of duplicate estimations are in satisfactory concordance. J. F. B. Estimation of Saccharin in Foods. J. Karas. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 559-560.)-1n order to prevent contamination of the saccharin by other substances when the former is extracted from a food by means of ether, the following procedure is recommended : The essential feature of the process consists in precipitating interfering substances by the addition of tannin and lead acetate before the saccharin is extracted, the author having proved by experiment that saccharin is not precipitated by these reagents.The fluid under examination, or an aqueous extract of a food, is evaporated in order to remove any alcohol which may be present, and the residual liquid is treated with tannin solution (15 C.C.of a 10 per cent. solution per 100 C.C. of liquid) and 8 C.C. of basic lead acetate solution, and filtered. The filtrate is then acidified with phosphoric acid, the lead phosphate is separated by filtration, and the saccharin is extracted from the filtrate by means of a mixture consisting of equal volumes of ether and light petroleum. The residue obtained on evaporating the solvent consists of pure saccharin. When the substance under examination contains much fat, this may be removed by rendering the liquid alkaline, and extracting with ether before treatment with tannin and lead acetate. w. P. s. Melnik (Bohemian) Wine. F. Cerny. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25,486-489.)-About one-half the quantity of wine produced in Bohemia is obtained from the province of Melnik. The vines are chiefly of the blue Burgundy variety, and were originally obtained from France. Analyses of thirty wines are recorded. The alcohol varied from 6.73 to 9.92 ; total solids from 1-71 to 3.82 ; glycerol from 0.65 to 1.24 ; acidity (tartaric acid) from 0.48 to 0.84 ; and ash from 0.14 to 0-39-all these results being expressed in grms. per 100 C.C. The wines were all free from sugar except in one case, (' Chhteau Melnik," where the quantity of sugar was 2.8 grms. per 100 C.C. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800321

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 327 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Chlorine Content of Blood and its Distribution between Serum and Blood-Corpuscles. J. Snapper. (Biochem. Zeitsch., 1913, 51, 53-62J-The author finds that if serum is treated with 2 to 3 parts alcohol, the alcoholic filtrate contains the total chlorine, whilst the precipitate is free from chlorine. The chlorine content of the corpuscles is from 40 to 45 per cent.of that of the serum. Assuming that the chlorine of the corpuscles is dissolved in the intraglobulsr liquid, this liquid is calculated to have the same chlorine concentration as the serum. E. W. Residual Reduction of Blood. P. Mayer. (Biochem. Zeitsch., 1913, 50, 362-369.)-1t is usual to estimate glucose in blood by measuring copper reduction and rotation, and correcting for other reducing and active substances by carrying out the same measurements after removal of glucose by fermentation. In order to determine whether this residual reduction is not partly due to substances formed during fermentation, 0.1 per cent.solutions of glucose were fermented with a number of pure culture yeasts. The results varied with the yeast used.I n numerous instances the fermented liquid was active, mostly dextrorotatory, but sometimes also lavorotary, and many reduced Fehling’s solution, The behaviour towards other reagents leaves no doubt that optical activity and reducing power are due to degradation products of yeast proteins, and not to unfermented glucose ; and, therefore, that glucose solutions of concentrations corresponding to those occurring in blood may, after fermentation, exhibit rotatory and reducing power, which may lead to a false inference as to the nature of the substances to which the residual reduction is attributed.E. W. Indicator Method for the Estimation of the Permeability of Cells by Alkalis. E. N. Harvey. (Amer. J. PhysioZ., 1913, 31, 335-342; through Chem.ZentraZbZ., 1913, 1, 1793.)-Results of an investigation carried out by the author show that the indicator neutral-red is equally sensitive towards ammonia and sodium hydroxide, even in the presence of proteins and lecithin, and that the indicator method is useful for the detection of alkalis in the interior of cells. Tubes containing egg albumin tinted with neutral-red, and others containing a mixture of egg albumin with proteins, starch, lecithin, caseinogen, vitellin, globulin, etc., were immersed in &T solutions of ammonia and sodium hydroxide respectively. The rate of diffusion of the alkali into the albumin, as shown by the change in colour of the indicator, was the same in every case.Similar experiments were made in which diluted egg albumin tinted with neutral-red was shaken with lecithin dissolved in various solvents; the action of ammonia and sodium hydroxide on the resulting droplets of lecithin was then observed.When the lecithin was dissolved in benzene, xylene, toluene, turpentine, carbon disulphide, or carbon tetrachloride, ammonia at once penetrated the droplets, whilst sodium hydroxide did not do so.On the other hand, both alkalis penetrated the droplets at the same rate when the lecithin had been dissolved in ether, ethyl acetate, ethyl butyrate, ethyl propionate, or ethyl valerate ; in this case a layer of albumin did not form round the droplete. w. P. s.328 ABSTRACTS OF CHEMICAL PAPERS Neutral Red Paper as Indicator for Alkalimetry of Serum. J. Snapper. (Biochem.Zeitsch., 1913, 51, 88-91.)-A concentrated solution of neutral red in 50 per cent. alcohol is diluted with 10 parts 50 per cent. alcohol. Filter-paper is soaked in this liquid and dried, and is prepared the same day that it is required. It is claimed to be superior to lacmoid in that it is not affected by proteins, and therefore gives a sharper end-point, and also that it can always be freshly prepared before use.E. W. Simple Method for Determining the Fermentative Activity of Milk and Various Feeding-Stuffs, and the Catalase Enzyme of Milk. A. Rosam. (Milch- wirtschaftl. Zentralbl., 1912, 42, 193 ; through Chem. Zentralbl., 1913, I., 1723.)- A modification of the Walter test is used. A weighed quantity, 1 to 5 grms., of the feed is warmed at 35" to 40" C .with water which completely fills a 50 C.C. tube shaped like an elongated conical flask, and connected by a rubber stopper to a rising tube. The level of the water is observed (1) twenty minutes, and (2) several hours after the tube is placed in the thermostat. As a standard, the fermentative activity which produces a rise of 30 cm. in three hours is taken as 100 per cent. (2$ = 100 per cent.).To determine the fermentative activity of feeding-stuffs on milk, sterilised milk is substituted for the water. The following figures were obtained : Sugar beet, 43 to 60 per cent.; fresh sliced roots, 30 to 50; sour sliced roots, 10 to 18; dry sliced roots, 25 to 40 ; fresh cabbage, dirty, 40 to 60; clover, 50 to 70 ; hay, 30 to 45; fresh brewers' grains, 0.5 to 5 ; used straw litter, 65 ; dung, 50 to 70 ; milk, 4 to 20.To apply the method to the estimation of catalase in milk, 150 C.C. of milk are treated with 50 C.C. of 1 per cent. hydrogen peroxide, and warmed in the apparatus at 25' C . The maximum quantity of gas is formed at 30" to 40' C. 0. E. M. Composition of Milk from Cows suffering from Foot and Mouth Disease. 0. Mesger, H. Jesser, and K. Hepp.(Zeitsch. U?ttersuch. N a b . Genussna., 1913, 25,513-551.)-Systematic analyses of milk from twenty-six cows suffering from foot and mouth disease are recorded, the results showing that the influence of the disease on the composition of the milk varied more with the individual cow than with the breed or lactation period. At the commencement of the disease the yield of milk diminished, but the composition, as regards the fat and proteins, showed an improve- ment, the milk containing a larger proportion of these two constituents ; an increase was sometimes noticed in the amount of ash, chlorine, and phosphoric acid contained in the milk.w. P. s. Estimation of Lactic Acid in Urine. H. Ishihara. (Biochem Zeitsch. 1913,50, 468-483.)-Ryffell's method (Proc.Physiol. Soc. 1909, 5) modified by estimating the acetaldehyde iodimetrically according to Ripper (ANALYST, 1901, 26, 131) estimates about + of lactic acid present and isvaluable as a rapid approximation, but cannot be used when sugar is present. For accurate work, lactic acid must be extracted with ether, but owing to its unfavourable distribution coefiicient this cannot be done in a separating funnel.In order to avoid emulsification, the urine is first precipitatedBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 329 with phosphotungstic acid, then with baryta, the excess of baryta removed by carbon dioxide, concentrated and acidified with phosphoric acid. The resulting syrup is extracted for twenty-four hours in a Lindt extraction apparatus, and the lactic acid estimated according to the method of Fiirth and Charnasy (ANALYST, 1910, 35, 445), modified and simplified in Bome details.The method tested on urine with added lactic acid gave yields of 89 to 99, and a mean of 92 per cent. of the total acid. Normal human urine was found to contain 0.08 grm. lactic acid per litre. E. W. Titration of Uric Acid in Urine after Silver Precipitation.E. Kretschmer. (Biochem. Zeitsch., 1913, 50, 223-233.)-Two hundred C.C. of urine are precipitated with magnesia mixture, made up to 300 c.c., filtered, and 200 C.C. of the filtrate precipitated with ammoniacal silver, as in Salkowski’s process. The silver precipitate is washed until the filtrate is free from silver and chloride, transferred to a, beaker, and decomposed with 15 to 20 C.C. concentrated sulphuric acid. The mixture is heated to boiling, immediately filtered from silver sulphate, and repeatedly washed with boiling water. The solution (about 250 c.c.) is cooled to 60 to 64’ C., and immediately titrated with $v permanganate. The filtration from the silver sulphate is essential, but the slight opacity that is sometimes observed in the filtrate does not interfere with the titration. The somewhat high results obtained as com- pared with those given by Salkowski’s method are probably due to the purin bases carried down in silver magnesium precipitate which are also oxidised ; they cannot be attributed to urea, since even a 0.1 per cent. urea solution is not oxidised by zn permanganate. E. W.

ISSN:0003-2654    

DOI:10.1039/AN9133800327

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 329 ORGANIC ANALYSIS. Studies of the Conditions of the Precipitation of Albumin by Picric Acid. H. LabbB and R. Maguiss. (Comnptcs rend., 1913, 156, 1415-1417.)-The precipitates formed with albumin by various reagents are generally of the type of adsorption compounds, or at any rate are readily dissociated on washing, so that they do not lend themselves to gravimetric estimations.The relations between the pro- portions of the reacting substances also are not constant, but are only represented by more or less complicated curves. DenigAs and, later, Vallery have worked out a, method for the estimation of albumin by precipitation with potassium mercury iodide, employing a curve for the expression of the results. The authors have now investi- gated a simple volumetric method for the estimation of egg albumin by precipitation by the citro-picric acid reagent prepared according to Esbach.If a fairly large excess of picric acid be used, the precipitation of egg albumin is complete and the clear filtrate is free from albumin. Starting with a, known quantity of picric acid, the quantity of acid remaining in the filtrate gives a, measure of that fixed by the precipitate.With increasing quantities of albumin and a constant quantity of picric acid, a series of numbers are obtained which may be plotted on a curve. Fifty C.C. of Esbach’s citro-picric acid reagent are diluted to 100 c.c., and the acidity is deter- mined by titration with FG sodium hydroxide in presence of phenolphthalein.Increasing volumes of a 10 per cent. solution of egg albumin are successively mixed with 50 C.C. of the picric reagent and diluted to 100 C.C. The excess of acid is then330 ABSTRACTS OF CHEMICAL PAPERS titrated on 25 C.C. of the filtrate. If the quantities of acid fixed expressed in C.C. of FT alkali be represented by y and the quantities of albumin taken by x, a curve may be constructed, which for values of x between 0.8 and 2.60 grms.is practically 76.08 a branch of a hyperbola, adequately represented by the formula--x =- - - 4. 18.24 - ZJ Such a curve is characteristic of adsorption compounds, and it has been found that the albumin-picric acid precipitate is dissociated by washing at a decreasing rate as the amount of picric acid remaining decreases, so that the last traces are held very firmly by the albumin.With the use of the curve above mentioned, the estimation of egg albumin may be effected by two simple acidimetric titrations. J. F. B. Estimation of Methyl and Ethyl AIcohols in the Presence of Each Other. J. Meyerfeld. (Chem. Zed., 1913, 37, 649-651.)-The method is based upon the same principle as that devised by Hehner (ANALYST, 1887, 12, 25).The mixture of the two alcohols is oxidised by heating it with a measured quantity of chromic acid solution in the presence of sulphuric acid, and the excess of the oxidising agent titrated with standard thiosulphate solution, C. A. M. Sampling Coal Deliveries. G. S. Pope. (U.S. Bureau of Nines, BuZZetin 63, pp. 68.)-Anthracite larger than pea, size is now bought by the United States Govern- ment on a guaranteed maximum percentage of ash on the dry coal.If this is exceeded, the Government has the option of refusing delivery or deducting 10 per cent. from the bill. Anthracite peas and smaller sizes are bought on a guaranteed maximum percentage of ash and minimum heat value, both calculated on the dry coal. Coal which is not up to specification may be refused, or 25 per cent.deducted from the price at the purchaser’s option. Bituminous coal is bought on a guaranteed maximum percentage of ash, volatile matter and sulphur, and minimum heat value, all calculated on the dry coal, and on a guaranteed maximum percentage of moisture in the coal as received. The determination of moisture is only made when the sampler suspects an undue percentage, and in such cases he is required to collect a special moisture sample with the utmost speed and without the refinements adopted to make the ordinary sample uniform, as such refinements would, by loss of moisture in the process, introduce errors, beside which the slightly more representative character of the sample would be negligible. These moisture samples are of about 30 to 50 pounds, and are rapidly crushed to 8 inch and quartered down to 3 pounds.The ordinary sample is collected with the utmost care to make it representative and without regard to moisture losses in the process, as the price to be paid depends directly on the heat value of the dry coal, and is subject to increase or decrease according to an agreed scale for every 1 per cent.that the ash is less or more than that named in the contract. It is laid down in the contracts that the gross sample shall be not less than 600 pounds in the case of slack and small anthracite, nor less than 1,000 pounds with larger coal, and it is shown in this bulletin that there is rarely any advantage in collecting a gross sample larger than 1,500 pounds. Detailed directions are given for mixing and quartering such quantities.When prepared byORGANIC ANALYSIS 331 hand, the pieces of coal and impurities are crushed to the approximate size indicated in the table below before each reduction : Weight of Saniple t,o be Divided. Size to which Coal and Impurities should be Broken before each Division. ... ... 1 inch 1,000 pounds or more , , .... 3 2 9 , ... - ... ... ... ... 500 pounds 4 9 , 250 Y Y 125 1 9 H 9 , 60 9 , + Y Y - ... ... ... ... ... .J - ... ... ... ... ... ... ... ... ... ... The &inch mesh sample is then reduced to about 3 pounds by quartering or, preferably, by the use of a mixing and reducing machine. G. C. J. NOTE BY ABsTRACTOR.-FOrmer~y the United States Government purchased coal on an “ as received ” basis.The change to the ‘‘ dry coal ” basis, and the reasons given for it on pages 8 and 9 of this bulletin, will disappoint those who believe that coal, like other commodities, should be paid for at a rate proportioned to its value to the user, and will be held by those who oppose that principle to give away the whole case for purchase to a specification controllable by scientific methods and not by rule-of -thumb arbitration.On pages 13 and 14 scathing comments are passed on specifications which provide substantial penalties for excessive volatile matter and sulphur. The Bureau of Mines only uses the percentage of sulphur and volatile matter to classify and identify coals, and this may serve their purpose. But a 2 per cent. excess of volatile matter in the case of anthracite would probably indicate substitution, and not improbably substitution of a coal which would gum up a gas engine in half an hour if run on gas ignition, or still more hopelessly, but after a longer run, if fitted with appliances for electric ignition.Again, though it may be admitted that sulphur has less to do with clinkering difiticulties than was formerly supposed, and that its tendency to give trouble of this kind can be overcome by simple means, the writer might have reflected that coal is used for other purposes besides firing boilers.His responsibility is very great, because his department led the way in the past in the purchase of fuel to specification, and future utterances of the department on the subject will be given weight for that reason and without any necessary reference to their intrinsic value.Studies on Cellulose. E. G. Parker. ( J . Phys. Chem., 1913, 17, 219.)--The estimation of cellulose depends upon its resistance to attack by ordinary reagents, which remove the accompanying non-cellulose substances. In Lange’s method this is effected by fusion with potassium hydroxide and water ; small variations in the procedure produce considerable variations in the results, but the chief defect lies in the constantly varying concentration of alkali, due to the loss of water by distillation.The method was therefore varied to the following : 0.5 to 2.0 grms. of the sample, of known moisture-content, were heated to 13Oo-14O0 C. with 50 C.C. of potassium hydroxide solution in a 500-C.C.round flask, by means of a paraffin-bath. When it332 ABSTRACTS OF CHEMICAL PAPERS had been heated for the desired time, the cellulose was washed with water, and then, on a Gooch crucible, with dilute acid, dilute alkali, water, alcohol, and ether ; it was then dried and weighed. With a 20 per cent. solution of the alkali, constancy was reached in fifteen hours ; with a 10 per cent.solution, in four or five hours ; with lower concentrations, down to the limit studied, the time is decreased as the dilution. The method was confined to surgical cotton-wool, which was found to contain 92 to 93 per cent. normal cellulose, 4-5 per cent. of cellulose, ekc., soluble in potassium hydroxide, and 3.25 per cent. moisture. Cotton reprecipitated from Schweitzer’s reagent gave irregular results ; further study of the reaction is thus necessary.0. E. M. Rapid Method of Testing Suction Gas Fuels for Liability to Clog Gas Engine Valves. W. McD. Mackey. (J. SOC. Chew. Ind., 1913, 32, 523-524.)-1t is pointed out that the percentage of volatile combustible matter in anthracite is no certain indication of the behaviour of the fuel as a source of producer gas for power purposes.Though a low percentage of volatile matter usually connotes a satisfactory fuel, and a high percentage rightly engenders suspicion, it ma.y happen that of two coals not differing greatly in their content of volatile matter, that with the larger amount may prove Satisfactory in use, whilst the other gives rise to trouble. It is suggested that the quality rather than the quantity of the volatile matter determines the difference, and the following test for volatile substances of relatively high boiling- point is recommended : About 3 grms.of the powdered coal is heated in a platinum crucible for seven minutes, the bottom of the crucible being just above the tip of the inner flame of a Bunsen burner.The crucible is supported in a ring of asbestos card- board, and covered by a 4-inch clock-glass containing 20 C.C. of water. If no tar is deposited on the clock-glass, the fuel may be considered satisfactory for use in a gas producer with the minimum provision for scrubbing the gas which characterises suction gas plants. G. C. J. Detection of Gelatin in Textile Dressings.E. Schmidt. (Fiirber-Zeit., 1913, 24, 97-98 ; through Chem. Zentralbl., 1913, I., 1896.)-Ammonium molybdate yields a flocculent white precipitate with gelatin solutions ; the precipitate dissolves partially when the mixture is heated, but forms again on cooling. Another sensitive reagent for gelatin is prepared by rendering Nessler’s reagent feebly acid with sulphuric acid and filtering off the red precipitate which is produced; the yellow filtrate yields a white turbidity when added to a gelatin solution, either hot or cold.Ammonium salts do not interfere with the reaction, but proteins other than gelatin must not be present. These two tests will detect as little as 0.01 mgrm. of gelatin in 5 C.C. of solution, a quantity which cannot be detected by the biuret or tannin tests.The substance under examination should be freed from fat and from albumin by means of nitric acid before the tests are applied, and alkaline solutions must be neutralised previously. w. P. s. Detection of Hydrocyanic Acid. C. Pertusi and E. Gastaldi. (Chem. Zeit., 1913, 37, 609-610.)-The solution to be tested for hydrocyanic acid is added drop by drop to a reagent prepared by mixing together 1 drop of 3 per cent.copperORGANIC ANALYSIS 333 acetate solution, 1 C.C. of 10 per cent. disodium phosphate solution, and 4 drops of a saturated solution of benzidine acetate. A turbidity followed by a bluish-violet coloration is obtained if the liquid contained as much as 0.000027 grm. of hydro- cyanic acid per c.c., whilst the phosphate prevents the analogous colorations otherwise given by iodides, ferrocyanides, etc., with benzidine acetate and copper acetate. A sensitive modification of the test consists in boiling the solution with sodium hydroxide for five to ten minutes, filtering it and passing a current of carbon dioxide through the filtrate, The liberated hydrocyanic acid is carried onwards into the reagent, which for this purpose consists of a mixture of 1 drop of 3 per cent.copper acetate solution, 5 drops of benzidine acetate solution, and 0-5 C.C. of water. Under these conditions a distinct coloration is obtained in the presence of 0.000007 of hydrocyanic acid (as cyanide) in 10 c.c., whilst no reaction is obtained with chromates, permanganates, persulphates, periodates, ferric chloride, etc.In the presence of metals which form double cyanides soluble in solutions of alkalis, a preliminary separation of the cyanides as silver salts from the bases is necessary, the test being then applied to the precipitate. Schonbein’s benzidine reaction with guaiacum tincture in the presence of a copper salt shows an analogous behaviour. If the tincture be freshly prepared and an addition of disodium phosphate made, the appearance of the colorations produced by bromides, iodide, and thiocyanates (but not cyanides) is prevented.(Cj. Lander, ANALYST, 1911, 36, 266.) C. A. M. Evaporation Test €or Mineral, Lubricating, and Transformer Oils. C. E. Waters. ( J . Ind. Eng. Chem., 1913, 5, 394-398.)-1t is shown by a series of parallel estimations that the results obtained in the evaporation test for lubricating oils are influenced to a, great extent by the size of the vessel.For example, an oil heated for various periods in a vessel 2 x 3 cm. in size showed an average loss of 0.23 per cent., whereas when heated under the same conditions in a vessel 5 x 3 cm. in size, it gave an average loss of 0.63 per cent. Hence, in order to obtain compar- able results, the same weight of oil must always be heated iu vessels of the same size.Brass is more suitable than glass as the material for the vessel, and it is suggested that convenient dimensions are 5 cm. internal diameter, and height 3 cm. A vessel may be made from brass tubing with walls 0.75 mm. thick, and the bottom of sheet brass not exceeding 0.5 mm.in thickness should be soldered to this with silver solder. In making an estimation, the oil (5 grms.) should be weighed with the aid of a pipette and rod into this vessel without smearing the sides. C. A. M. Estimation of Pentoses in Presence of Other Sugars by Means of the Speetroscope. (Chem. Zeit., 1913, 37, 621.)-- Tollens’ phloroglucinol-hydrochloric acid reaction for the detection of pentoses may be modified so as to serve as the basis of a quantitative method.A permanent coloration may be obtained by heating the reagents in alcoholic solution, and the diluted solution shows one to three absorption bands, the intensity of the colour being proportional to the quantity of pentose taken. In a flask of 150 to E. Pinoff and K. Gude.334 ABSTRACTS OF CHEMICAL PAPERS 200 C.C.capacity, fitted with a reflux condenser, are placed 25 C.C. of the aqueous pentose solution, which should not contain more than 3 per cent. of pentose, 25 C.C. of hydrochloric acid of sp. gr. 1-19, 50 C.C. of 96 per cent. alcohol, and 0.6 grm. of phloroglucinol. The mixture is heated on the water-bath for half an hour, counting from the time the alcohol begins to boil.The flask is quickly cooled to avoid loss of alcohol, a portion of the solution is measured out and placed in a Hehner's colorimeter cylinder with the addition of so much alcohol that the spectroscope just shows faintly one or two of the characteristic absorption bands in the red and the yellow regions. The degree of dilution required to effect this result, ie., the number of volumes of alcohol added to the coloured solution, ~ 1 2 ~ s 1, multiplied by 0.0948, gives the percentage of pentose in the original solution.An original solution con- taining 0.0948 per cent. of pentose, 25 C.C. of which are treated according to the above method, when placed in a Hehner's cylinder in front of the spectroscope, will just show the bands with the limiting degree of intensity without any dilution with alcohol.A Hehner's cylinder is a graduated vessel of exactly 3 cm. internal diameter ; any other cylinder of the same diameter may be used for the test. Other sugars do not interfere with the results, and since the method is a spectroscopic and not a colorimetric one, coloured solutions do not interfere. The method has been satisfactorily applied for the estimation of pentose in urine, and the experimental error does not exceed 0.1 per cent., even when the liquids contain over 2 per cent.of pentose. J. F. B. Analysis of Paints and Especially Lithopones. P. Nicolardot. (Ann. Chim. anal. appl., 1913, 18, 184-186.)-The paint, etc., is treated with hot toluene to separate the oil from the mineral matter, the latter attacked with dilute hydro- chloric acid beneath the surface of the toluene, and the liberated hydrogen sulphide conducted through two absorption vessels containing fuming nitric acid, followed by vessels containing sodium hydroxide and potassium permanganate solution respec- tively. Five grms.of the sample are weighed into a small tube, which is introduced into the reaction flask, the outlet of which is connected with the absorption vessels.An addition of 50 C.C. of toluene and 150 C.C. of hot water is then made, and after separation of the oil, 5 C.C. of hydrochloric acid are introduced little by little, and the contents of the flask heated nearly to boiling-point. When the reaction slackens, a slow current of air is passed through the apparatus, and the heating continued for about two hours until hydrogen sulphide is no longer evolved.The toluene layer is then filtered, the filter washed with hot toluene, the filtrate and washings dried over potassium carbonate and evaporated, and the residue of oil dried at 105" C. and weighed. The lower layer in the flask is also filtered, and the insoluble residues on the two filters are dried, ignited, and weighed (barium sulphate, silica, etc.).Zinc sulphate is estimated in the acid solution, and the sulphur from the oxidation of the hydrogen sulphide is estimated in the contents of the first three absorption vessels, the permanganate solution in the fourth vessel being used to show that the absorp- tion in the other vessels was complete. Should the fourth vessel contain any sulphate the estimation should be repeated more slowly.C. A. M.ORGANIC ANALYSIS 335 Preparation of Specifications for Petroleum Products. I. C. Allen. (US. Bureau of Mines, Technical Paper 36.)-In its efforts to increase efficiency in the utilisation of petroleum products, the Bureau has undertaken the preparation of specifications for certain petroleum products purchased by the Government.The task is a difficult one, and requires for its adequate performance much information which is not yet available. Recognising the importance of the work undertaken by the International Petroleum Commission, the Bureau has promoted co-operative research, in which its own staff, the Petroleum Commission, the American Chemical Society, the American Society for Testing Materials and other bodies, and private chemists and engineers are taking part.A list is given of thirty fundamental factors to be considered in petroleum testing, and of fourteen classes of products for which it is desirable to prepare specifications. G. C. J. Effect of Temperature, Acid Coneentration, and Time in the Bromination of Phenol for Quantitative Determinations.L. V. Redman, A. J. Weith, and F. P. Broek. ( J . Ind. and Eng. C?ae972., 1913,5,389-393.)-The solutions employed are TG sodium thiosulphate, TD bromide-bromate (2-76 grs. potassium bromate, and 15 grms. bromide per litre), 20 per cent. potassium iodide, and 0.5 per cent. starch solution. The bromide-bromate solution is standardised iodimetrically against the thiosulphate solution.Into a 500 C.C. glass-stoppered bottle are placed 50 C.C. water, 5 C.C. hydrochloric acid (sp. gr., 1.2), and 15 C.C. of the phenol solution. This last, if necessary, should be diluted to TV strength. Sufficient TG bromide-bromate solution is now added while slowly shaking to give a slight permanent yellow coloration. The temperature at this point should be about 22" C.The stopper is replaced, and the whole shaken continuously for one minute, after which 0.5 C.C. potassium iodide solution is added, the bottle again shaken for a minute, and the titration finished with thiosulphate, the starch indicator not being added until the colour is almost discharged. Each C.C. of bromide-bromate solution is equivalent to 0*00156 grm. phenol.The results show that phenol may be rapidly determined as tribromophenol by bromination to within an error of 0*00005 grm. The quantities of reagents as generally recommended may be decreased with advantage. Two per cent. excess of free bromine is sufficient for the complete bromination of phenol in one minute in A large excess (over 50 per cent.) of potassium iodide above that necessary for complete reduction of the free bromine according to the equation is not required.It is shown that not more than 50 per cent. excess potassium bromide over that called for by the equation acid solution at 22' C. KBrO, + 5KBr + 6HC1= 6KCl-t- 3B,r + 3H,O need be used in making the standard bromide-bromate solution. The amounts recommended by the U.S. Pharmacopoeia demand an excess of 340 per cent.Complete liberation of the iodine by the free bromine may be effected in one minute if thorough diffusion be obtained by sufficient shaking. The acidity of the solution in which the tribromophenol is precipitated must not fall below 0.48 normal if the bromination is to be complete in one minute; an acidity of 0-5 to 1.0 normal336 ABSTRACTS OF CHEMICAL PAPERS is advised.(cf. ANALYST, 1912, 37, 515). Low temperatures retard the reaction; 20' to 30' C. is recommended H. F. E. H. Estimation of Phenol in Presence of Organic Matter. E. M. Mumford. (Chem. News, 1913, 107, 253.)-Ordinary methods for estimating phenol are un- suitable when applied to solutions which have been subjected to bacterial action and contain large quantities of peptone and other proteins.The method adopted is based on the principle that phenol-sulphonic acid is readily nitrated, and can then be converted into amnionium picrate by the action of ammonia, and colorimetrically estimated. A suitable volume of the phenol-containing liquid is warmed with a few C.C. of concentrated sulphuric acid to 80" or 90' C., and into the warm liquid is then run a volume of 10 per cent.potassium nitrate sufficient to oxidise the organic matter present, and at the same time the phenol-sulphonic acid will be nitrated. The whole is then warmed, and if necessary boiled, to destroy the organic matter, until the liquid is straw-yellow or colourless. When cool and rendered alkaline with concentrated ammonia, the colour is matched against a standard solution of phenol- sulphonic acid which has been nitrated and made alkaline in a similar manner.Extreme accuracy is not claimed for the method, but 0.0001 grm. phenol can be thus estimated. The method is applicable to the estimation of a and P-naphthols. H. F. E. H. Report on the Present State of Rubber Analysis. F, W. Hinrichsen. (Sixth Congress Int. Sssoc. Testing Materials, New York, 191 2 ; through Chem.Engineer, 1913, 18, 165-166.) - Some iuternational agreement on the methods of rubber analysis would be desirable. The analysis of crude rubber should preferably always be made on the mechanically washed, air-dry material. The moisture is determined by drying a portion of the sample in vacuo over sulphuric acid at a gentle heat. For estimating the resin, 5 grms. of the sample, finely-chopped, are extracted with acetone in a Soxhlet apparatus for ten hours ; it is recommended that the body of the extraction apparatus be made of brown glass to avoid any action of the light on the material under treatment.The dimensions of the apparatus should be agreed upon. Direct methods for the estimation of caoutchouc are unreliable; this con- stituent is determined by difference after estimating the ash and proteins (N x 6-25>. The analysis of vulcanised rubber mixtures is often very difficult, so that the united German cable manufacturers have adopted for standard insulations only mixtures which contain matters which can be determined by analysis-vie., in addition to caoutchouc and sulphur, only inorganic matters and hydrocarbons of the paraffin series (ceresin).When the mixture contains pitch, tar, asphalt, and the like, a satis- factory analysis is impossible. In many cases the following scheme is recommended : Five grms. of the sample are extracted with acetone, as in the case of crude rubber. This treatment will dissolve, in addition to the original rubber resins, any resins possibly added, free sulphur, oils, hydrocarbons of the paraffin series, and wax.The sulphur is determined in the evaporated acetone extract of a separate sample by oxidation with nitric acid and bromine. Solid hydrocarbons are approximately estimated by taking up the evaporated acetone extract with alcohol, and cooling thisORGANIC ANALYSIS 337 solution to - 5" C.When oils and foreign resins are present, the accurate estima- tion of the rubber resins is not possible; otherwise they may be calculated by difference. The saponification value has little or no significance on account of the variable nature of the resins. The material left after extraction with acetone is boiled for four hours under a reflux condenser with paraffin oil of high boiling-point, which dissolves the rubber and allows the filling matters to be filtered off or removed by centrifuging after the addition of benzene.Another portion of the material after extraction with acetone is boiled for four hours with alcoholic potassium hydroxide ; this saponifies the usual substitutes ; the acids of these are precipitated and separated by ether. Many of the substitutes used will have already yielded portions soluble in acetone.The total sulphur is estimated by oxidation with nitric acid and magnesium nitrate in a spherical flask, or else by electrolytic oxidation in nitric acid. From this is deducted the free sulphur (soluble in acetone), the sulphur combined with inorganic fillers and the sulphur in the substitute fatty acids ; the difference repre- sents the sulphur combined with caoutchouc.Lastly, the moisture and the protein are estimated, and the balance is expressed as caoutchouc. J. F. B. Direct Determination of Rubber. L. G. Wesson. (J. Ind. and Eng. Chem., 1913, 5, 398.)-The procedure consists in allowing the acetone-extracted sample to dissolve or swell up in carbon tetrachloride, after which nitrous gases are passed in to form the nitrosite of rubber.The composition of the nitrosite is immaterial so long as it contains all the carbon of the rubber. After standing, the soluble nitrosite is dissolved in acetone, from which it is obtained by a method of precipitation or evaporation, in a form ready for combustion. The percentage of carbon so found is a measure of the rlzbber originally present.A special electric combustion-furnace is employed, and the material is burnt in a boat made of lead peroxide and red lead. The use of this boat, which absorbs the sulphur of the nitrosite as lead sulphate, should also give a means for the estimation of the sulphur of vulcanisation if, as seems probable, the sulphur combined with the rubber is carried quantitatively into its nitrosite.Some selected analyses give excellent results, but further work is required to test the reliability of the method and to eliminate the numerous sources of error encountered. H. F. E. H. Use of the Kottstorfer Value for the Estimation of Resins and Substi- tutes in Caoutchouc Articles. M. Vallery. (&lonit. scient., 1913, 3, 82-83 ; Chem. Zentralbl., 1913, I., 1634-1635.)-More simply than by the usual method of extraction with alcoholic sodium hydroxide, the percentage of resins and substitutes may be estimated by determining the Kottstorfer value of the sample-viz., the quantity of potassium hydroxide in mgrms.absorbed by 1 grm. of the sample. The results, though not exact, are sufficiently good, and the method possesses the advantage that it is not influenced by the inorganic loading materials, so that a previous treatment with acetic acid is unnecessary.A weighed quantity of the rasped sample is boiled under a, reflux condenser for three hours with such a quantity of alcoholic sodium hydroxide solution that the decrease in alkalinity is at least one-fifth of the original strength. After cooling, a slight excess of standard hydrochloric acid is added, and338 ABSTRACTS OF CHEMICAL PAPERS the excess is titrated back with & sodium hydroxide in presence of phenolphthaleln.From the quantity of sodium hydroxide consumed during the boiling the Kottstorfer value is calculated. It is necessary to correct the result by a blank experiment under the same conditions. Duplicate estimations should not differ by more than 3 units.The author has investigated the influence on the results of the state of subdivision of the sample. Estimations were made using cubes of various sizes of the same sample. The results showed that the results obtained when using cubes were very much lower than with the rasped material. Moreover, they increased at a slower rate than the total surface-area, of the cubes.Thus the alkali does not act only on the surface of the particles, but penetrates to some extent. However, the equilibration of the concentration between the surface and the interior appears to take place very slowly, so that the action of the alkali on the cubes of cut caoutchouc is only very incomplete as compared with its action on the rasped material. Hence the use of rasped material is essential. J. F. B. Maumene Figure of Oil of Turpentine. C. Grimaldi and L. Prussia. (Chem. Zeit., 1913, 37,657.)-A reagent is prepared by running from a burette 1 part of sulphuric acid (sp. gr. 1.84) into 7.5 parts by volume of cold iso-amyl alcohol. Twenty C.C. of the oil are pipetted into a Dewar's vacuum-tube, the temperature taken with a stirring thermometer, 10 C.C. of the freshly prepared reagent introduced, and the rise of temperature noted. In the case of pure fresh oils of turpentine (French, Spanish, Portuguese, Austrian, Greek, and American) the values ranged from 77 to 85.7, and remained practically constant after distillation of the oils over lime. The fraction of the oils boiling between 155' and 156" C. (corresponding to the pinene) gave Maurnen6 figures varying from 76.7 to 834, even after distillation over metallic sodium. On the other hand, oxidised oils gave much higher values (sometimes over loo), and the mixture turned brown, but after distillation over metallic sodium the Maumenk figures of the original oils were obtained. Pine oils of various origins gave results varying within wide limits, but never exceeding 47.2 ; whilst pinoline and rosin essence (Austrian and American) gave a maximum value of 30.1, and petroleum derivatives and tar oils (benzene, zylene, toluene) showed prac- tically no rise of temperature. In the case of pine oils and rosin essences the rise in temperature was increased by starting from a higher temperature-e.g., 25" C.-but turpentine oil value8 were not materially affected by this factor. The method should detect relatively small quantities of petroleum spirit and pine oil in oil of turpentine. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800329

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

338 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Preparation of Petermann’s Ammonium Citrate Solution. F. Zohren. (Chem. Zed, 1913, 37, 611-612.)-Petermann’s solution (ammonium citrate) may be prepared without loss of ammonia by adding the ammonia to the citric acid in a small filter-flask provided with a side tubulure. The cork of this flask has two openings, through one of which passes a stirring device worked by a small motor, whilst the ammonia solution is added through a dropping funnel, the end of which delivers below the surface of the liquid.The place where the stirrer passes throughINORGANIC ANALYSIS 339 the cork is made secure by a piece of rubber-tubing drawn over the inner part of the stirring rod, and having its end dipping below the liquid.The flask is cooled in a bath of running water, and its side tubulure is connected with a small washing bottle containing a small weighed quantity of citric acid dissolved in a little water. This is subsequently added to the solution in the mixing flask, and its weight is taken into account. C. A. M. Rapid Methods for Estimation of Antimony. H. Nissenson. (Zeitsch. anorg. Chem., 1913, 81, 46-48.)-No new methods are described, but alternative rapid methods for both sulphide and oxidised ores are given in sufficient detail, with references to the original papers in which they were first described.With the exception of the electrolytic method, no method more than ten years old is recom- men de d. G. C. J. Purification of the Precipitate obtained in Estimating Barium as Sulphate. F.A. Gooch and D. U. Hill. (Zeitsch. anorg. Chenz., 1913, 80, 397- 401.)-The paper relates to elimination of alkali salts by treatment with concentrated sulphuric acid and evaporation to dryness, which treatment results in the formation of a coarse crystalline precipitate, from which the alkali salts are easily washed out. The evaporation can be completed in half an hour if a Hempel burner is available, but occupies several hours, and requires much care, if an ordinary ring burner is used.The authors tried directing a blowpipe flame on the surface of the liquid contained in a crucible, but as erratic results were sometimes obtained, they recom- mend the following arrangement : A cone of fine platinum gauze, with a base some- what greater in diameter than the crucible containing the liquid, is inverted in the crucible; the blowpipe flame is then directed against the apex of the cone, which should not touch the liquid. Five C.C.of sulphuric acid can be evaporated without loss in half an hour. The maximum error of a barium determination conducted in this manner is k1.5 mgrms. on a weighing of 0.5 grm. The test precipitations were made in presence of 2 grms.of potassium chloride, Without purification of the precipitate, the average error was over +I per cent. G. C. J. Contribution to the Study of the Colour Reactions of Chlorates. 1. E. Pozzi-Escot. (Bull. SOC. Chim., 1913, 13, 498.)---To 1 C.C. of the chlorate solution is added two drops of aniline sulphate solution (1 in lo), and 3 or 4 C.C.of concentrated sulphuric acid are poured down the side of the tube. At the common surface of the liquids a blue colour is formed if 0.00005 grm. of chlorate is present. If benzidene sulphate is used instead, an orange-yellow colour shows the presence of 0-000005 grrn. of chlorate. 0. E. M. Influence of Chlorine on Determination of Nitrates by Phenol Disulphonie Acid Method.R. Stewart and J. E. Greaves. ( J . Amer. Chem. Soc., 1913, 35, 579-582.)-The influence of chlorides on the determination of nitrates by the Grandval and Lajoux method is well known, but it is not generally recognised that the use of chloroform, to inhibit the action of bacteria in soil extracts, may result in the forma-340 ABSTRACTS OF CHEMICAL PAPERS tion of ionic chlorine in amount sufficient to cause an error of 50 per cent. in a nitrate determination, This is especially the cam when the lime method is employed, which method is recommended for use with soils rich in organic matter, since a clear solution is thus obtained ; but in such cases chloroform should not be used.With 1 grm. of lime and as little as 2 drops of chloroform to 50 grms.soil, after standing overnight, small quantities of nitrate may be underestimated by more than 50 per cent., and even very large quantities by 20 per cent. Experiments are described which show that the above errors are due to the formation of chlorides, as a result of the decomposition of chloroform by lime. G. C. J. Titration of Chlorine Bleaches. F. Ducelliez. (Bull. SOC. Chim. 1913,13, 494.)-The author has worked out a method depending upon the evolution of oxygen in presence of cobalt peroxide.For the valuation of chloride of lime, 2 grms. of the sample are heated with 0.5 grm. of cobalt chloride in a tube containing 50 C.C. of water, by means of a water-bath. The volume of gas collected in a measuring tube, after correction for temperature and the tension of aqueous vapour, and for the oxygen absorbed in converting cobalt oxide to peroxide (1.2 C.C.for 0.5 grm. cobalt chloride), gives the value of the sample in Gay Lussac degrees. The method is applicable to alkali hypochlorites. The specimen results show satisfactory agreement between this and the arsenious acid method. 0. E. M. Electrolytic Determination of Copper in Solutions containing Nitric Acid.E. Gilchrist and A. C. Cumming. (Chem. News., 1913, 107, 217.)-The electrolytic determination of copper in solutions containing nitric acid is inaccurate, owing to the formation of nitrous acid, with consequent incomplete deposition of the last traces of copper. It appeared probable that the addition of urea would effect an improvement, due to destruction of the nitrous acid, and experiniental evidence is adduced in support of this.To prove that the gain was really due to the destruction of nitrous acid by the urea, bright copper was subjected to the action of very dilute nitrous acid solutions of different strengths, in the presence of nitric acid, both with and without urea, and in no case was more than 1 mgrm. of copper dissolved in the presence of urea, while over 200 mgrms.of copper dissolved when no urea was added. If a little urea is added towards the end of a copper deposition, the current can be stopped and the vessel washed out without any resolution of copper, provided that no unnecessary time is spent on the process. The large dilution which results from the usual siphoning method of washing is thus obviated.The best current to employ is not above 3 ampdres, with a potential difference of 2.5 to 3 volts. H. F. E. H. Estimation of Sodium Carbonate and Copper in Mixtures of Soda Ash and Blue Vitriol by Titration with Potassium Hydroxide. H. J. F. de Vries. (Zeitsch. anal. Chem., 1913, 52, 350-%7.)-Mixtures of soda ash and blue vitriol are used in agriculture, and their approximate analysis therefore assumes some impor- tance.On account of the difficulty of titrating the strongly coloured solution which masks ordinary indicators, some analysts have been content to calculate the contentINORGANIC ANALYSIS 341 of sodium carbonate from the result of a determination of carbon dioxide. But since soda ash may contain sodium bicarbonate, the results of a carbon dioxide determina- tion may give rise to erroneous conclusions, unless controlled by a determination of total alkali.The author makes use of the first appearance of a turbidity due to basic copper sulphate as indicator. The substance is dissolved in a measured quantity of & acid and the solution is boiled to expel carbon dioxide, cooled, and the excess of acid titrated with potassium hydroxide, ceasing the addition of alkali when a turbidity makes its appearance.A deduction of 0.05 C.C. is made from the consumption of alkali, this being the amount required to produce a visible turbidity in 50 C.C. of solution. If a determination of carbon dioxide is also made, the amount of sodium carbonate and bicarbonate present can be calculated.If potassium hydroxide be added to a neutral copper sulphate solution in presence of phenolphthalein, there is no evidence of the presence of the indicator until the copper is almost wholly precipitated; but long before the quantity of potassium hydroxide reaches the proportion of two molecules to each atom of copper, there is a sharp colour change, easily recognised by comparison with a flask contain- ing a similar mixture, but without phenolphthalein. On this observation, an empirical method has been founded for the estimation of copper in mixtures of copper salts with soda ash.After determining total alkali as described, phenol- phthaleh is added and the titration with potassium hydroxide continued until the colour of the precipitate appears to change from bright ultramarine to a violet shade.The amount of copper present is then given by the number of C.C. of Tv alkali used, multiplied by an empirical factor. With a final volume of 45 to 70 C.C. and addition of potassium hydroxide at a rate of about 5 C.C. per minute, the factor is 0.00428. Variation in the speed of addition of the alkali has more influence on the results than reasonable variation of any of the other conditions.If the speed be only half that stated, the factor becomes 0.00434. G. C. J. Development of Eleetro-analysis. R. Fresenius. (Zeitsch. anorg. Chem., 1913, 81, 4-23.)-An historical retrospect of the development of electro-analysis from the time of Wolcott Gibbs’ first quantitative experiments to the present. References are given to all the original communications, including some only to be found in text- books by their authors, which have been proved by experiecce to mark important advances. The tendency of recent researches to simplify apparatus on the one hand, and on the other to devise rapid methods for accomplishing difficult separations, even at the expense of some complexity of plant and procedure, is noted, and the need for and prospect of advance in both directions pointed out.G. C. J. Determination of Hydrogen, Nitrogen, and Methane in Gas by Com- bustion in a Quartz Tube. Mathers and J. E. Lee. (Chenz. En,gineer, 1913, 18, 159-162.)-The use of the Winkler-Dennis conibustion pipette, even as modified by the authors, presents certain difficulties and inherent errors. I n this pipette a platinum spiral is heated by means of external electrical connections, and the gases, mixed with an excess of oxygen, are burnt over mercury.If, however, the tempera- ture be sufficiently high to insure complete combustion, the mercury is oxidised and342 ABSTRACTS OF CHEMICAL PAPERS an error due to absorption of oxygen is introduced. Probably the best method is that of Drehschmidt, in which the gas is passed through a heated platinum capillary tube.This apparatus, however, rapidly deteriorates. The authors therefore propose to substitute for the platinum capillary a quartz tube charged with pieces of scrap platinum. The quartz tube used W ~ B 30.5 cm. long, 7.25 mm. outside diameter, and 3.38 mm. inside. Its capacity was 3.317 C.C. The platinum scrap was prepared by cutting up platinum wire as short as possible, flattening the fragments, and packing them in the tube with pieces of platinum gauze at each end.The charge weighed 11.189 grms., with a volume of 0,522 C.C. A mercury pipette containing the gas and oxygen for combustion was connected to one end of the quartz tube by a capillary tube and rubber connections.A mercury burette adapted to receive the gas was connected to the other end. The burette was surrounded with a water jacket, the water of whiqh could be circulated and mixed by raising and lowering a bottle con- nected with the jacket, thus preventing unequal temperatures between the top and bottom of the burette. The quartz tube was heated with a Bunsen burner with flattened flame, an asbestos board being suspended about 5 mm.above the tube to restrict radiation. The initial temperature of the gas in the pipette having been noted, the quartz tube was heated up, the air being displaced into the burette. The gas in the pipette was then slowly passed through the tube over glowing platinum into the burette, then back into the pipette, and finally again into the burette.The quartz tube was rapidly cooled, the cock connecting it to the burette was closed, and the temperature equalised in the water-jacket. After reading the volume of gas in the burette, it was corrected for variation from the initial temperature. For hydrogen, this procedure is sufficient to give accurate results. For hydrocarbons, the carbon dioxide in the burette must be absorbed and the volume thus found must be corrected for the quantity of carbon dioxide remaining in the volume of the quartz tube unoccupied by platinum.For the estimation of nitrogen, the gas must be mixed with an excess of oxygen, the nitrogen in which has been accurately determined; after combustion, the carbon dioxide and the excess of oxygen are absorbed in the usual reagents, and the residue then consists of the nitrogen in the gas plus the nitrogen introduced with the oxygen.J. F. €3. Volumetric Estimation of Hypophosphorous Acid and Hypophosphites. L. Marino and A. Pellegrini. (Gazx. Chim. Ital., 1913, 43, 494-497.)-A measured quantity of a dilute solution of the hypophosphite is boiled and treated with a solution of permanganate until permanently pink, after which the liquid is acidified with sulphuric acid (1 : 3) and the excess of permanganate titrated in the usual way.The permanganate solution is prepared by dissolving 6 grms. of potassium permanganate in about 800 C.C. of water, adding 40 grms. of potassium carbonate and 04 grm. of potassium hydroxide and diluting the liquid to a litre. After standing for a day it is filtered through asbestos and standardised upon oxalic acid solution (12.6 grms.of oxalic acid and 36 grms. of sulphuric acid (1 : 3) per litre). If a mixture of hypo- phosphorous and phosphorous acids be boiled with a sulphuric acid solution of a bismuth salt, a bismuthate of the metal is deposited, and the hypophosphorous acid is oxidised to phosphorous acid, which may then be estimated in the filtrate by theINORGANIC ANALYSIS 343 permanganate method described above.The results are only approximately correct, however, owing to the oxidation of the hypophosphorous acid by the bismuth being not quite complete. C. A. M. Rapid Method of Estimating Lead Peroxide in Minium. C. Finzi and E. Rappuzzi. (Zeitsch. anal. Clzent., 1913, 52, 358-367.)-The substance (I grm.) is introduced, together with 30 to 40 C.C.of water, into a 200 to 250 C.C. flask furnished with a two-hole stopper-one hole accommodating a tap funnel, the other a gas exit tube. The gas exit tube is connected by thick-walled rubber-tubing to a Schiff's nitrometer. The water in the flask is boiled to expel air, a little water introduced through the tap funnel to clear its tube of air, and boiling continued for a few minutes, after which the rubber exit tube is clipped and the contents of the flask allowed to cool somewhat.About 20 C.C. of a solution containing 12 per cent. of hydrazine acetate and 10 per cent. of acetic acid is next run in through the tap funnel, connec- tion is re-established with the nitrometer, and the solution is warmed and finally boiled until all the nitrogen has been driven over into the nitrometer.N2=2PbO,. Hydrazine sulphate is not a convenient reagent owing to its slight solubility, the reaction being very slow in presence of much water. Moreover, the lead sulphate formed tends to protect the minium from reduction. A concentrated solution of hydrazine acetate may be prepared by treating the finely powdered sulphate with excess of a concentrated solution of barium acetate, filtering off barium sulphate and diluting and acidifying the filtrate to the strength named above. The results obtained by the method are closely concordant, but are about 7 per cent.higher than those obtained by Topf's (iodimetric) method. G. C. J. Estimation of Manganese in Soil.M. J. Stritar. (Zeitsch. anal. Chem., 1913,52,337-345.)-For the estimation of manganese in soils, the bismuthate method is recommended. Small quantities of chloride (up to 0.01 grm. chlorine) are without influence on the results, provided ferric salts are absent, but this is rarely the case in an acid extract.of a soil. From acid extracts of soils containing less than 1 per cent.of soluble calcium salts, hydrochloric acid is easily expelled by evaporation with sulphuric acid. But in the more common cases where the extract contains consider- able quantities of calcium salts, this method is not recommended. In such cases the solution is evaporated twice or more in some cases with nitric acid; any chlorine remaining is precipitated by addition of silver nitrate, .and the excess of silver pre- cipitated by addition of the smallest possible excess of thiocyanate, the ferric salts naturally present or some added iron alum serving as indicator.The mixture is made up to known bulk, filtered through a dry paper, and an aliquot portion of the filtrate is mixed with sufficient nitric acid, treated in the cold with excess of sodium bismuthate or bismuth peroxide, filtered through asbestos, quickly decolourised by addition of a measured volume of a standard solution of hydrogen peroxide, and the excess of the latter titrated with permanganate as usual.G. C. J. Some Quantitative Separations of Neodymium. T. 0. Smith and C. James. (J. Amer. Chem. SOC., 1913, 35, 563-566.)-During the separation of the344 ABSTRACTS OF CHEMICAL PAPERS crude rare earths as oxalates from acid solutions of minerals, it has been observed that varying amounts of other elements accompany the precipitate.The experi- ments described in this paper were conducted with a view to determine the magni- tude of the error involved in the separation of neodymium from titanium, glucinum, uranium, barium, and zirconium. When a slight excess of oxalic acid is added to a boiling solution containing 0.2 grm. of neodymia and an equal or greater amount of the oxides of glucinum and uranium, the separation is quantitative, the maximum error observed being f0-2 mgrm.In presence of barium chloride, the recovery of neodymia was always about 0.6 mgrm. low. Since zirconium oxalate is insoluble in water but soluble in oxalic acid, the latter must be added in considerable excess to effect a satisfactory separation of zirconia and neodymia ; the neodymia is always overestimated by about 0.8 per cent.I t is suggested that the separation would be sharper if the solution to be analysed were poured into excess of a boiling solution of oxalic acid, the method adopted in the experiments with titanium.Of these ten experiments, seven gave results within 0.1 mgrm. of that indicated by theory, but the remaining experiments show errors of - 0.6, - 2.2, and - 3.1 mgrms. on a weighing of 0-14 grm. G. C . J. Estimation of Ozone and Hydrogen Peroxide. V. Rothmund and A. Burgstaller. (Monatsh., 1918, 34, 693-704.) - Hydrogen peroxide can be deter- mined iodimetrically if molybdic acid is employed as catalyst.Molybdic acid is 100 times as effective as iron salts, and has the further advantage that it appears to have no accelerating effect on the reaction between potassium iodide and atmos- pheric oxygen. As the reaction between hydrogen peroxide and potassium iodide is very slow except in strongly acid solution, the attempt was made to estimate ozone and hydrogen peroxide in presence of each other by taking advantage of the fact that ozone reacts quantitatively with iodine in neutral or alkaline solution.After treat- ment with faintly alkaline or neutral iodide, the solution was made faintly acid, the iodine titrated with thiosulphate, and the solution then treated with molybdic acid, a large amount of sulphuric acid and more iodide, and the iodine liberated calculated to hydrogen peroxide.The results both for ozone and hydrogen peroxide were 10 to 20 per cent. low, and the probable causes of error are discussed in the paper. The separate estimation of ozone and hydrogen peroxide when occurring in solution together can be accomplished as follows : The solution is made faintly acid (about &), cooled to 0" C., and about 1 per cent.of potassium bromide is added, then at least as much potassium iodide as corresponds to the ozone, and the solution is titrated with & thiosulphate. More iodide is now added, as well as 1 C.C. of Fa- ammonium molybdate and 16 C.C. of dilute (I : 5) sulphuric acid. After five minutes the freshly liberated iodine is titrated with thiosulphate. 21= H,O,.The process is necessarily conducted in apparatus which prevents the escape of bromine vapour. The maximum error for ozone is - 0.5 per cent., and for hydrogen peroxide + 0.4 per cent. 21= 0,. Suitable apparatus is figured in the text. G. C. J. Estimation of Phosphoric Acid. L. Moeser and G. Frank. (Zeitsch. anal. Chem., 1913, 52, 346-349.)-The following method is recommended for the estimationINORGANIC ANALYSIS 345 of phosphoric acid in mineral phosphates.I t depends on the separation of all the bases as sulphates which are insoluble in strong alcohol, whereas phosphoric acid is readily soluble in that solvent, The substance is treated with about 5 C.C. of sulphuric acid, which is kept near its boiling-point for from ten to fifty minutes according to the nature of the substance.To the cooled mixture, about 30 to 40 C.C. of 95 per cent. alcohol is added, together with 2 C.C. of 10 per cent. alcoholic potash. The purpose of the potash is to give a coarsely crystalline precipitate of potassium sulphate, which carries down the finely-divided sulphates of calcium, iron, and aluminium, and assists filtration. The mixture is stirred, allowed to cool again, and then filtered through a paper previously wetted with alcohol.The residue and paper are washed four or five times with 95 per cent. alcohol, and the filtrate and washings are diluted with an equal bulk of water, made alkaline with ammonia, heated nearly to boiling, and the phosphoric acid precipitated by means of magnesia mixture. The highest and lowest results on pure tricalcic phosphate were 61.32 and 61-08 per cent. PO, (theory= 61.21).Four series of experiments on natural mineral phosphates show about the same extreme divergence between the results of duplicate determinations, all the results being a little higher (about 0-1 per cent.) than those obtained by the molybdate method. I t is said that large quantities of manganese, such as may occur in basic slag, interfere, but no example is given to show the magnitude of the error.The small quantities of manganese present in some natural phosphorites are shown to have no measurable influence on the accuracy of the results. G. C. J. Radiation of Uranium Solutions and Estimation of Uranium by Measure- ment of Radio-aetivity. L. Miehiels. (Zeitsch.aizorg. Clzem., 1913, 81, 49-60.) -In the absence of radium, uranium in solution may be estimated with fair accuracy by observation of the rate at which the solution discharges a suitably designed gold- leaf electroscope. Such an instrument is figured in the paper. The solution is contained in a shallow glass dish, about 8 cin. in diameter, which is placed 3.5 cm. below the lowest point of the leaves of the electroscope.The time of discharge is independent of the depth of the layer of solution, provided this exceeds 5 mm., and depends only on the area of the dish, the concentration of the solution, and the normal leak of the instrument. With the same dish, the reciprocal of the time of discharge less the reciprocal of the time of equal diminution in charge in a control experiment with water is very nearly proportional to the concentration of uranium, and exactly proportional to it if the control and other solutions are adjusted to equal density by addition of ferric chloride or some other salt without measurable radio- activity.This consists of a quadrant electrometer, of which one pair of quadrants is earthed and the other pair is connected to one plate, A, of a condenser, the second plate, B, of which is raised to a definite potential. The solution to be tested, contained in a shallow dish as described, is placed between the plates of the condenser, Finally, the pair of quadrants which are connected to the condenser are put in connection with the earth, but with a very high resistance, R (e.g., a tube of xylene), interposed.I n consequence of the ionisrt- tion induced by the uranium solution, an electrical current passes through the A direct reading-form of apparatus is also described.346 ABSTRACTS OF CHEMICAL PAPERS condenser, the plate A and the quadrants connected to it receive a charge, and the needle of the electrometer is deflected more and more. But since the pair of quadrants connected to the condenser is earthed through a high resistance of the order of magnitude of an air gap, a part of their charge will leak away through that resistance, The current leaking through the resistance is a function of the potential of the charged quadrants, and increases with that potential in accordance with Ohm's law ; consequently a moment must arrive when the current leaking through the resistance equals the current in the condenser.At this moment the needle of the electrometer comes to rest. The greater the current passing through the condenser, the greater the potential necessary to drive an equal current through R. The potential is thus proportional to the current which, under standard con- ditions, is proportional to the concentration of the uranium solution.For every concentration of uranium, therefore, there is a definite position of equilibrium for the needle of the electrometer, which can be calibrated to give direct readings of uranium concentration (cf. ANALYST, 1913, 231). G. C. J. Preparation of Conductivity Water. R. Bourdillon. (J. Chenz. ~ o c . , 1913, 103, 791-795.)-Work on the conductivity of dilute solutions has mostly been done with water possessing an electrical conductivity of at least 0-7 gemmho (0.7 x 10-6 reciprocal ohms), requiring considerable correction and leading to anomalous results.A T Y C 145 cm.), with a narrow side tube, E, soldered The author describes a still which will deliver 7 to 8 litres of water of conductivity below 0.2 gemmho in a single distillation from Oxford tap-water.The boiler A is of copper, and holds about 13 litres. It is closed with a rubber cork, through which passes a copper tube, B (1-3 cm. external diameter, 8-5 metres long), coiled into a spiral of nineteen turns (thus form- ing an efficient spray trap), with its lower end fixed by a rubber cork in a copper cylinder, C. B and C are jacketed with cotton waste and boiler felt, about one- fifth of the steam is condensed here, and escapes through the glass tube G, bent as shown to prevent loss of steam. The un- condensed steam pasees on through D into the condenser F, which is a vertical tin tube (2.5 cm.by in with pure tin 45 cm. from tho bottom. F is surrounded near the top and bottom by glass tubes, through whichINORGANIC ANALYSIS 347 cold water circulates, and is closed at the top by the glass cap, K, affixed by a rubber ring, and fitted with a soda-lime tube, L, and at the bottom by a glass cap, M, joined by rubber tubing at P to the receiver of the distilled water, and carrying a side tube, N, through which is introduced a continuous current of purified air (about 3 litres per hour), passing out at L.The air is purified by being passed through glass spirals containing concentrated sulphuric acid and potassium hydroxide solution, followed by a long soda-lime tube. The boiler is filled with tap-water, to which has been added about 5 grms. of potassium hydrogen sulphate. All connections must be kept perfectly air-tight, any leak causing a large rise in the conductivity of the water. If the distillation is carried on fairlyfast (1.2 litres per hour), the conductivity of the water falls rapidly, and remains at 0-13 gemmho after one litre has been collected.Distillation should be stopped while 2 or 3 litres remain in the boiler to prevent incrustation with calcium sulphate. Similar results are obtained if phosphoric acid is used in place of the acid sulphate, but if no chemicals are used a large quantity of mediocre water is obtained, which only falls to 0.17 gemmho after four and a half houra’ distillation.Very slightly better results are obtainable by starting with distilled water in place of tap-water. Tap-water, acid potassium sulphate, and no air- current result in obtaining a water which never falls below 0.25 gemmho.A condenser of only 46 cm. long proved unsatisfactory. Nothing is gained by using such low COG- ductivity water in a conductivity cell which is not air-tight; and on storing such water in 3-litre Jena glass flasks, fitted with siphon outlet tubes, and with air inlets protected by soda-lime tubes, the conductivity rose from 0.12 gemmho to 0.2 in two or three days, and to 0.45 gemmho in a few weeks.It will keep for B month or two without exceeding 0.5 gernmho. (Cf. W. R. Bousfield, ANALYST, 1912, 37, 474.) H. F. E. H. Estimation of Water formed on Burning Substances containing Nitrogen and Sulphur in a Calorimetric Bomb. 0. Rau. (Zeitsch. anorg. Chem., 1913, 81, 116-121.)-The results obtained by the use of the bomb calorimeter include the latent heat of the steam, which is almost wholly condensed to liquid water.To cal- culate the lower heat value, corresponding to the production of uncondensed steam, a tolerably accurate moisture determination is necessary. The requisite degree of accuracy may be deduced from the facts that coal on combustion yields some 40 per cent. of water, the latent heat of which approximates to 3 per cent.of the total heat value of the cod, and that for the best calorimetric work anaccuracy of 0.2 per cent. can be claimed. The least troublesome method of estimating the moisture is to com- bine this determination with the calorimetric experiment, but the nitric acid which may be derived from nitrogen in the compressed “oxygen,” and the nitric and sul- phuric acids resulting from the combustion of substances containing nitrogen and oxygen, complicate matters, the nitric acid tending to be absorbed and weighed as water, the sulphuric acid acting in a contrary sense by holding back moisture. Several proposals to effect the estimation with sufficient exactness are discussed and shown to be less satisfactory than the following method which is recommended. A few decigrms.of anhydrous sodium carbonate are weighed out into the bomb before the experiment, together with 20 to 30 porcelain shot, When the thermometric348 ABSTRACTS OF CHEMICAL PAPERS readings are completed, the bomb is rolled on its side, so that the sodium carbonate solution is spread by the shot all over the inner surface, and the gases are allowed to discharge slowly through tared absorption tubes containing concentrated sulphuric acid. The bomb is then heated to llOo C.in a paraffin-bath, and a current of dry air drawn through it and the absorption tubes, Moisture may be estimated in this way with an error which in no case introduces an error as great as 0.1 per cent. into the corrected heat value of the fuel. A weighed amount of sodium carbonate being taken, the determination of nitrogen and sulphur in the residue in the bomb by titra- tion presents no difficulty.Since under ordinary conditions of combustion the sul- phur in fuel is only oxidised to sulphur dioxide, and the nitrogen dot at all, whereas in the bomb they are converted into sodium sulphate and nitrate, and since also the excess of sodium carbonate is converted with liberation of heat into bicarbonate, which dissolves with absorption of heat so far as the water present is sufficient for its solution, it is shown that the results of the calorimetric experiment need correction by the subtraction of 2020 S + 650 N + 160 A - 4 W calories where S and N represent the weight in grms.of sulphur and nitrogen oxidised, A the weight in grms.of sodium carbonate employed and W the weight in grms. of water formed. The last term, 4 W, representing the heat abaorbed by the solution of sodium bicarbonate so far as the amount of water present suffices for this, is a quantity less than 2 calories, and therefore negligible compared with the quantity of 7,000 calories under measurement. The other terms represent quantities which together may amount to 1.5 per cent.of the heat value of the coal. G. C. J. Estimation of Water in Volatile Products of Destructive Distillation. G. Lambris. (Zeitsch. anorg. Chenz., 1913, 81, 24-39.)-The present paper is con- cerned with the accurate determination of moisture in unpurified coal gas, and the method described depends on the absorption of moisture, ammonia, pyridine, and phenol by phosphoric anhydride, retention of these substances by the phosphoric anhydride even at 180" C., at which temperature other constituents of the gas mixture which may have condensed on the surface of the reagent are expelled, and subsequent determination of and correction for the amount of ammonia, pyridine, and phenol absorbed.I t is shown that neither ethylene nor benzene, toluene, xylene, or naphthalene interferes, The behaviour of substances of higher boiling- point than naphthalene was not investigated.The purest phosphoric anhydride obtainable commercially is seldom free from yellow phosphorus, which gives rise to trouble if the contents of the drying-tube are simply distilled with caustic alkali to determine the ammonia and pyridine.If, however, the contents of the drying-tube are allowed to deliquesce by exposure to air, then treated with water and filtered through a hard filter, the finer particles of phosphorus are oxidised, and the larger ones withheld by the paper. A measured volume of gas is passed through a tared U-tube containing phosphoric anhydride. A current of dry nitrogen or other indifferent gas is then led through the tube, which is heated to 180° C.to expel naphthalene, etc. TheINORGANIC AWALYSIS 349 tube is then reweighed, and its contents are allowed to deliquesce as described. The solution of the residue is filtered and distilled with excess of caustic alkali, the ammonia and pyridine in the distillate being titrated with -& sulphuric acid, using 1 C.C.of a 0.1 per cent. solution of Congo red as indicator. The contents of the still are then acidified with sulphuric acid, and the phenol is distilled over in a current of steam, and estimated iodimetrically as follows: A measured and excessive quantity of a standard bromide-bromate solution is added to the distillate, and the excess of bromate determined by addition of potassium iodide and titration with thiosulphate.61 = C,H,OH. I n the neutralised distillate of ammonia and pyridine, the latter is estimated as follows : Ammonium sulphate (0.5 grin.) is added to the neutral solution, which is evaporated to dryness and heated to 130" C. for exactly fifteen minutes. Under these conditions nearly the whole of the pyridine is expelled, and the small amount left is exactly balanced by a, slight loss of ammonia.The residue is taken up with water, the free sulphuric acid is titrated with alkali, using Congo red as indicator, and the result is calculated to pyridine, with due regard to the fact that the end- point of the titration is reached when only 94 per cent. of the pyridine is neutralised. Congo red is chosen as indicator because when a solution of ammonia is mixed with one of pyridine and titrated with Congo red, the result is the same as though the two solutions were titrated separately.This is not the case when methyl orange is used. The colour-change with Congo red is much more gradual than with methyl orange, and the use of a control-flask containing a neutral solution of ammonium sulphate tinted with Congo red is essential.G. C. J. Qualitative Analysis of the Zinc Group. R. E. Lee, R. H. Uhlinger, and F. 0. Amon. ( J . Anher. Chewz. Xoc., 1913, 35, 566-579.)-Experiments are described which show that the methods usually adopted for the separation of the metals of this group leave much to be desired, and the following scheme of analysis is recommended as certain to detect as much as 0.5 mgrm.of zinc, manganese, nickel, or cobalt in 30 to 40 C.C. of solution. The group reagent recommended is hydrogen sulphide gas, which is passed through the slightly ammoniacal solution. The latter should be warmed if less than 1 mgrm. of either metal has to be looked for. By the use of hydrogen sulphide gas in faintly ammoniacal solution, very little nickel passes into the filtrate, and this small amount is easily coagulated by boiling for a few minutes. Separation of zinc and manganese from nickel and cobalt by the use of dilute hydrochloric acid is unsatisfactory, ag the latter metals are by no means insoluble in normal acid and zinc sulphide in presence of nickel or manganese sulphide is not readily soluble in weaker acid.The mixed sulphides are treated with 10 to 20 C.C.of dilute (1 : 12) hydrochloric acid, and if a black residue remains, a few crystals of chlorate are added, and the mixture boiled, diluted somewhat, and filtered from separated sulphur. The filtrate is evaporated to a few C.C. to expel excess of acid, and made slightly alkaline with 20 per cent. sodium hydroxide. If the precipitate is so bulky that a gelatinous mixture results, 10 to 20 C.C.of water are added. After cooling, excesfi of sodium peroxide is added by350 ABSTRACTS OF CHEMICAL PAPERS small additions, and the mixture is heated to boiling and filtered. The filtrate, which contains all the zinc and none of the other metals, is acidified with acetic acid and tested by passing hydrogen sulphide through the warmed solution. The precipitate consists of hydrated manganese dioxide, nickelic and cobaltic hydroxides. The object of peroxidising the mixture and of accomplishing this before any great excess of alkali hydroxide is present, is to insure complete precipitation of cobalt, cobaltous hydroxide being appreciably soluble in excess of alkali hydroxide. The mixed hydroxides, freed from zinc by washing, are dissolved in the least possible quantity of warm dilute (1 : 12) hydrochloric acid, and the solution is filtered from any filter-paper fluff, concentrated to about 2 c.c., and boiled with 5 C.C. dilute (1 : 20) nitric acid until red fumes cease to be evolved. About 10 to 20 C.C. of stronger (1 : 1) nitric acid are then added, together with a few crystals of chlorate, and boiling continued for a, few minutes. The precipitate of manganese dioxide is filtered off on asbestos, supported on glass wool in a funnel, and its identity, almost beyond doubt, can be confirmed by the lead peroxide test. The filtrate is evaporated to 5 C.C. to expel excess of acid, diluted by addition of 10 to 15 C.C. water, and filtered if turbid. Sodium hydroxide is then added until the solution is neutral, or until a permanent precipitate begins to form. The solution is then divided into two portions, one of which is examined for the presence of cobalt by rendering just distinctly acid with acetic acid and warming with an equal volume of a saturated solution of potassium nitrite. The other half of the solution is treated with potassium cyanide until the precipitated cyanides just redissolve, heated for two or three minutes, filtered if necessary, made strongly alkaline with sodium hydroxide, and oxidised by adding bromine water until the solution is permanently red, when nickel, if present, is precipitated as black nickelic hydroxide. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9133800338

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

350 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Apparatus for the Preeipitation of Barium Sulphate. H. G. Smith. (J. Ind. and Eng. Chem., 1913, 5, 416.)-A special form of dropper is made by bending an ordinary ;-inch test-tube up at an angle of about 45' 1+ inches from the open end, drawing out the lower side of the bend, breaking oflf the small projection so formed to a point, and fusing the opening so that it will deliver about 80 drops per minute when lying horizontally on the top of a beaker with the opening downwards.The volume of barium chloride solution required for the precipitation is placed in this test-tube, and both tube and contents are immersed in the boiling solution, the dropping-point of the special tube being well above the level of the liquid in the beaker.H. F. E. H. New Method for Determining the Diffusion of Dissolved Substances. L. W. ()holm. (Meddelanden fran K. Vetenskapsakademiens Nobelinstitut, 1912, 2, No. 22 ; through Chem. Zentrabl. 1913, I., 1648.)--Four hollow brass cylinders are placed one above the other, and diffusion allowed to take place from the bottom one, containing the solution, to the others, containing solvent. After diffusion the contents of the cylinders may be examined separately. The apparatus is intended for viscousAPPARATUS, ETC.351 solutions, such as lithium or potassium chloride in glycerol-water mixtures, which would adhere too strongly to glass. 0. E. M. Apparatus for the Exact Analysis of Flue Gas. G. A. Burrell and F. M. Seibert. (U.8. Bureau of Mines? Technical Paper 31.)-A modified Haldane apparatus, specially designed for the analysis of flue gases, including the estimation of the small proportions of methane and hydrogen which may be present in such gases.I t is pointed out that as little as 0-1 per cent. of unburned combustible gases passing through a flue may represent a loss of 1 per cent. of the fuel, and that hydrogen and methane, as well as carbon monoxide, may be present, though their estimation is seldom attempted. This is attributed largely to the lack of any convenient apparatus.That now described makes possible a complete analysis of a flue gas in a little over half an hour. Duplicate analyses of the flue gas from a boiler operating under very poor conditions gave-hydrogen, 0.23 and 0.24; methane, 0.01 and 0.02 ; carbon monoxide, 0.98 and 1-02 ; oxygen, 9.43 and 9-45 ; and carbon dioxide, 9.90 and 9-91 per cent.G. C. J. Extraction Apparatus for Solids and Liquids. H. Aron. (Bioclzem. Zeitsch., 1913, 50, 386-388.)-The material ,to be extracted is contained in a suitable vessel suspended in a wide glass tube, the lower end of which is attached to a flask, and the upper end of which is drawn out so as to allow of connection with condenser.The apparatus is claimed to be superior to usual forms, and can be obtained from the Vereingten Fabriken fur Laboratoriumsbedarf in Berlin N. E. W. Improvement in Gas Thermo-Regulators. A. Whitaker. (Chenz. News, 1913, 107, 242-243.)-Mercury, when used as a L L cut-off" in ordinary gas regulators, offers many disadvantages, such as adherence to the glass, or failure to enter the fine orifice of the inlet tube.The author describes various improvements in the method of grinding the essential parts of the instrument, thus allowing for better fitting and smoother and more regular working. The end of the capillary should be countersunk (by grinding) as flat as is compatible with its object ; when the regulator exhibits an angle of 135' the flow of gas is much facilitated, and is approximately equal from all points. The end of the inlet tube is ground internally to a cone, the edges being either sharp or slightly expanded, and brought very near to the prepared capillary. Such an instrument was found to be sufficiently quick in action to prevent any fluctuation exceeding 0-1" C.for several days in a bath with no stirring arrangement, provided a small bulb quick-responding thermometer is employed. For maximum sensitiveness the regulator should be clamped with the end of the inlet tube horizontal, coinciding with the surface of the mercury, thus giving a very sharp cut-off. Illustrations of the apparatus are given, and it is supplied by Messrs. A. Gallenkamp and Co., London. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9133800350

出版商:RSC    

年代:1913

数据来源: RSC