摘要:

A CURIOUS M ~ A T - P R I i ~ S ~ ~ R V ~ ~ T I V ~ ~ ~ . B Y ALFRED c. CHAPMAS, F.1.C. (llcc~tl nt the n h t i l l g , Nowiibe7- 2, 1898.) SOBIF, time ago I received for analysis an antiseptic solution intended for the pieservation of meat. The liquid, which was colourless, possessed a mixed odour of sulphurous and benzoic acids, and proved on examination to have a somewhat remarkable coiiiposition. The analysis, which was only qualitative, revealed the presence of the following substances : aluininiuni sulphate, sodium chloride, sodium nitrate, sulphurous acid, chloral hydrate, benzoic acid, and a sinall quantity of iodine, apparently existing as hydriodic acid. The aluiii was evidently intended to axert its astringent effect upon the fibre of the meat, whilst the remaining constituents (with the exception, perhaps, of the chloral) are, of course, well known to be possessed of marked preservative and antiseptic properties. Both the chloral and the benzoic acid would doubtless be volatilized during the cooking of the meat, and310 THE ANALYST.this fact probably suggested the use of benzoic instead of the more active salicylic acid. In the course of my practice I had never before encountered chloral hydrate as a constituent of a food-preservative, and I thought that a short note calling atten- tion to its use for such a purpose might not prove uninteresting to the members of this Society. DISCUSSION. DR. RIDEAL said that preservatives of this kind were almost invariably of French He had met with several, the composition of which was similar in character Chloral hydrate was present in some, but not in The main idea of the manufacturers of such mixtures seemed to be to use a large origin. to that of Mr. Chapman’s sample. all. number of different ingredients, apparently with a view to baffling analysts.

ISSN:0003-2654    

DOI:10.1039/AN898230309b

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

310 TRE ANALYST. CONTRIBUTION TO THE CHEMISTRY OF DRYING OILS; WITH A METHOD FOR THE EXAMINATION O F LINSEED OIL. BY OTTO HEHNER AND C. A. MITCHELL, B.A. (Read at the Neeting, November 3, 1898.) OUR present kuowleage of the composition and constitution of the fluid fatty acids occurring in natcral fluid glycerides dates back no further than the year 1888, when K. Hazura, together with a number of collaborateurs, published a series of exceed- ingly important papers in the iYoizatslzefte fiir Clzewzie. Up to that time the fluid portion of oils, drying and non-drying, was described as olein. Hazura showed that when fluid fatty acids obtained from various oils were oxidized in alkaline solution with potassium permanganate, a number of different hydroxy-derivatives were produced. H e isolated and described the characteristics of these compounds, and concluded from his investigations that the unsaturated fatty acids from fixed oils take up as many hydroxyl groups as there are free valencies, yielding saturated hydroxy-fatty acids containing the same number of carbon atoms as the original molecule.He also showed that the unsaturated fatty acids in question combined directly with bromine, as many bromine atoms being fixed as there are free valencies. He thus differentiated between acids of different degrees of non- saturation, and supplied a scientific explanation of the Hiibl iodine value. We give in a tabular form a statement of his results : TABLE I. Original Acid. Oleic (C18H3402) Linolenic !C18H3002) Isolinolenic ( c , s %oO, ) Bromo-compound, Dibrom- stearic acid C18H34Br202 Te t rabrom- steaxic acid C18H%2Br402 Hexabrom- stearic acid %*,0Br,O2 - 31.P. Liquid 114-115" C. 177" C. Oxidation Product. M. P. 137" C. 173" C. 203" C. 173-175" C.THE ANALYST. 311 From the yields of the hydroxy-derivatives, which, as will be seen from the following tables, were very far from quantitative, Hazura and Grussner made an approximate estimation of the composition of the unsaturated acids of a number of oils : TABLE 11. 100 Grammes of Liquid Fatty Acids yielded : I \ Linseed. Hemp. Nut. Poppy. Cotton. Dihydroxy-stearic acid . . . 1.2 4.0 2.5 8.5 23.0 Sativic acid ... ’ . I . ... 6-5 24.0 25.0 18% 31.5 Linusic + isolinusic acids ... 20.3 2.5 2.0 0.3 - --- -- 28.0 30.5 29.5 27.3 54.5 TABLE 111. Approximate Percentage Composition of Liquid Fatty Acids.Linseed. Hemp. Nut. Poppy. Cotton. --. -~ --- _ _ Oleic acid ... ... ... 5 15 7 30 40 Linolic acid . . . . . . ... 15 70 80 65 60 Linolenic ( acids Isolinolenic j’ 15 1 15 13 5 0 * * * 65 j’ ... I t is obvious from the numbers given in Table 11. that there must have been a considerable destruction of the first products of oxidation, especially of those derived from the least saturated acids ; Hazura, in fact, obtained a number of further oxidation- products, indicating the rupture of the molecule. Nevertheless, it may be interesting to compare Hazura’s estimates and the iodine values deduced therefrom, with the actual iodine numbers recorded for the fatty acids from the several oils, bearing in mind that the latter are for the total free fatty acids, while Hazura’s numbers are for the unsaturated acids only. TABLE IT? Linseed.Hemp. Nut. YOPPY- Cotton. Iodine number calculated from Hazura’s results . . . ... 251 181.5 187 158 145 Iodine value of total acids ... 160-180 141 145 139 113 The calculated iodine value of oleic acid is 90; of linolic acid, 181.4 ; and of linolenic and isolinolenic acid, 274.1. With regard to isolinolenic acid, Hazura and Grussner inferred its existence solely from the oxidation-products formed ; they did not obtain a bromo-derivative, and hence did not isolate the acid. After making allowance for the presence of saturated fatty acids, it will be seen that there is an approximate correspondence between the calculated and the actual figures in the case of all but the linseed oil, which is said to contain about 15 per cent.of solid acids. We have repeated some of Hazura’s work, and. have prepared some, at least, of the derivatives discovered by him, paying particular attention to the bromine- derivatives.312 THE ANALYST, On adding a sufficiency of bromine to an ethereal or acetic .acid solution of linseed fatty acids, kept at a temperature of about 5" C., an abundant precipitate immediately forms. Part of this is exceedingly insoluble, while a part can be washed away with ether. The insoluble portion is the hexabrom-derivative of Hazura, although the composition of the substance does not exactly correspond with the formula, even after extraction for days with ether. Thus, in four separate experiments we obtained compounds with the following percentages of bromine : Found.1. 61.38 2. 61.47 3. 61.80 4. 61.64 Theoretical. 63-31 We found the melting-point from 180" to 181" C., while Hazura gives 177" C. We determined the percentage of bromine-derivative yielded by a considerable number of samples of linseed oil fatty acids, and found them to vary from 20 to 26 per cent. Hazurs obtained from 100 parts of the fluid linseed oil acids 40 of hexabromide, having a melting-point of 177' C. We believe that his precipitates must have included a considerable proportion of tetrabromide, seeing that it is dificult to entirely wash the latter out, as the above analyses of the persistently w.ashed products show. After the hexabromide has been filtered off, precipitates are obtainable which contain upwards of 50 per cent.of bromine, the tetrabromide formula requiring 53.32 per cent. of bromine. The part remaining in solution, when recovered by the evaporation of the solvent, consists of a semi-solid mass, evidently a mixture of dibromide and tetrabromide. This we found to contain 45 per cent. of bromine, the pure dibroniide requiring 36.18 per cent. The tetrabromide of Hazura can be much more readily obtained froin maize oil fatty acids than from linseed. But here, again, the actual percentage of bromine, even after numerous crystallizations from alcohol, falls somewhat short of the theoretical amount. Our product contained 51.97 per cent. of bromine, against a theoretical 53.32 per cent. The melting-point was 113.4" C. (corr.), against Hazura's 114" to 115' C.The dibroniide we have not been able to obtain in a pure condition. On boiling the hexa- and tetra-bromine compounds with alcoholic potassiuiii hydroxide the bromine is entirely eliminated. Theory requires for complete elimina- tion of the bromine froin the hexa-compound 51.8 per cent. of potassium hydroxide. I n four separate deterininations 51.33, 51.61, 51.50, and 51.5 per cent. of potassium hydroxide were consumed. On liberating the free acids from the resulting alkali salts no crystallizable substances could be obtained, the products being viscid yellow oils, which did not dry after being exposed to the air for a week, and which were, there- fore, neither the hydroxyacids, which result from oxidation by pernianganate, nor the less saturated products which would have resulted froin an elimination of 6HBr from the molecule.At the same time, the oil absorbed iodine from Hubl's solution to the extent of 61 to 63 per cent. After the titration of the excess of iodine added, the solutions rapidly became blue again from the further liberation of iodine. On re-bromination hydrobromic acid was evolved, and the original hexabromide was not reproduced, In this particular it behaved like the acids froin boiled linseed oil,THE ANALYST. 313 The bromine can likewise be completely removed from the dibromides and tetra- bromides by boiling with alcoholic potassiuni hydroxide, and the acids thus obtained are also oily fluids with low iodine absorption. Hazura, by reduction of the hexa-bromide with zinc and hydrochloric acid, prepared linolenic acid, which, however, owing to its oxidizable nature, could not be obtained pure and with the theoretical iodine value.He found 245, as compared with the theoretical 274.1. We have also made efforts in this direction, taking every pre- caution to keep away oxygen, yet were not more successful, since the iodine absorption of our linolenic acid only reached 241.8. The acid obtained was a nearly colourless oil of a specific gravity 0.9228 at 15.5" C. (compared with water at the same temperature) which absorbed oxygen from the air with great rapidity and quickly became dark brown. On dissolving this linolenic acid in acetic acid and adding bromine, the hesabroniide was produced, but not quantitatively, only 46 to 50 per cent.of the yield being obtainable; dense fumes of hydrobromic acid were given off. With the advance of oxidation in a linseed oil the yield of hexabromide decreases with the decrease in the iodine value. A linseed oil with an original iodine value of 160-7, with a yield of hexabrornide of 22.5 per cent, (probably not quite pure hexa- compound) on the fatty acids, was heated on the water-bath for a day and air blown through at intervals. The iodine value of the fatty acids was 147.3, and the yield of insoluble bromo-compound obtained under precisely the same conditions as before was 16.7 and 15.9 per cent. respectively in two determinations. X sample of boiled linseed oil, with an iodine value of 115.2, gave absolutely no precipitate on treatment with bromine, but hydrobromic acid was evolved.I t appears probable to us that the amount of hydrobromic acid produced will be found to bc a measure of such oxidation as occurs during the '' boiling " of linseed and other oils. It will be remembered that McIlhinoy (ANALYST, xix., 141) has already made experiments, from which he deduces a method for the determination of resin-acids in linseed oil, based upon the elimination of hydrobromic acid on hromiuation. We have also submitted the unsaturated fatty acids obtained from niaize oil to oxidation with alkaline permanganate, and are in a position to entirely confirm Hamra's statements as to the composition and properties of sativic acid, except that the melting-point of our purest substauce was 1 7 4 O , instead of 173" as found by him.Acting upon the fatty acids liberated froin other oils with bromine, we found that almond oil, with an iodine value of 95.68, gave no solid product of any kind. Mixtures of almond and linseed oil acids yielded amounts of insoluble bromide corresponding very approximately to the percentage of the linseed oil acids present, provided the operations were always carried out under precisely the same conditions as to amount of acids taken, temperature, solvent used, and washing. Quantities of from 0.2 to 0.3 grammes of the fatty acids were dissolved in 10 C.C. of acetic acid and the solution cooled to 5" C. in a corked flask. Bromine was then added drop by drop until a permanent bromine colour was observed. After standing for three hours the liquid was filtered through a Soxhlet tube containing asbestos, and washed with chilled acetic acid, alcohol, and ether, in successive portions of 5 C.C.each. The residue, which was white, was dried in the water-oven to constant weight. Attempts to use314 TEE ANALYST. larger quantities of fatty acid were unsuccessful, owing to the difficulty of filtration and washing until colourless in a Soxhlet, tube. Acids used. Linseed oil ... . . . Almond oil ... ... Linseed + almond 7 , , l Poppy oil ... . . . Poppy + linseed ... 7 ) 7 ) ... Cotton-seed oil ... Cotton-seed -t. linseed TABLE I-. Linseed Oil, Per Cent. ... 100 ... 0 ... 7.9 ... 9.7 ... 20.2 ... 37.5 ... 0 ... 18.3 ... 37.3 ... 0 ... 43.3 ... 60.1 Insoluble Eromide, 21 Linseed Oil Acid cnl- Per Cent. culated from Bromide.0 0 162 7.7 1.97 9.3 4.24 20.1 7.53 35.3 0 0 3.35 16 8.1 7 38.9 0 0 8.43 40.1 11.6 55.2 It need hardly be said that poppy-seed and cotton-seed oil acids also furnish the tetrabromide, which,. however, comes down more slowly than the hexabromide, and is inore or less completely removed by washing the deposit. The deposit from poppy- seed oil acids melted at 112" C., and that from cotton-seed oil acids at 113" C. Although the results stated in the preceding table are fairly satisfactory, yet the method is so empirical as not to commend itself. Moreover, when larger quantities of acids are operated upon, tetrabromide is apt to come down simultaneously with the hexa-compound, and to wash this free from the former considerable quantities of solvent are necessary, in which the hexabromide is not completely insoluble.X more reliable method is to obtain the mixture of solid compounds, washing this but slightly in order to remove readily soluble dibromide, and then to determine the percentage of bromine in the dried and weighed precipitate. From the amount of bromine found it is easy to calculate the relative proportion of the hexabromide in the mixture by means of the formula = 172, 63.3 x (100 - x )53*3 __ ~~ 100 100 or 10 x = 100 (m - 53.3) or IL' = 10(m - 53*3), in which f i z equals the percentage of bromine found, x the required percentage of hexabromide, and 63.3 and 53.3 the respective percentage of bromine in the pure hexa- and tetra-compounds. To illustrate this mode of working an outline of an experiment on linseed oil acids may be described. About 2 grarnmes of linseed oil acids (which by the method used in the experiments given in Table V.yielded from 20 to 23 per cent. of insoluble bromides) were brominated, but the deposit was washed with a far larger amount of acetic acid and ether than previously mentioned. By this washing the amount of deposit was reduced to 13 per cent., which melted at 179" C., and was therefore practically pure hexabromide. The filtrate and washings were allowed to concentrate spontaneously, whereby a further crystalline deposit amounting to 8-1 6 per cent. wasTHE ANALYST. 315 obtained. This deposit contained 58-8 per cent. of bromine, which, calculated by the formula given above, corresponds to 4.48 per cent. of hexabromide. .Hence, the total percentage of hexabromide equalled 17.48.The filtrate from the second precipitate did not yield any further solid deposit, but only a heavy yellow oil. This mode of operating may afford a solution of the problem of determining the relative percentages of oleic, linolic and linolenic acids in a mixture of fluid fatty acids, provided the saturated fatty acids are first separated. Further experiments on this important point will be carried out. The idea naturally suggests itself to obviate the separation of the acids from oils and to operate upon the glycerides instead. When an oil, the fatty acids of which give insolubIe bromine-compounds, is dissolved in ether or other suitable solvent, and bromine is added, there is an immediate precipitate produced, which is much more insoluble than the acid hexabromide, and consequently can be washed readily and efficiently.The precipitate can be collected either in a Soxhlet tube, if the quantity taken is small, or on a counterpoised filter, but we recommend the method of working which we employed for the estimation of stearic acid in mixtures of fatty acids (see ANALYST, vol. sxi., p. 322) ; but instead of filtering through cotton we find the best filtering material to be thin flexible chamois-leather tied over the end of the small thistle-funnel, from which any adhering precipitate can afterwards readily be removed by washing. From 1 to 2 grammes of the glycerides are dissolved in 40 C.C. of ether, to which a few C.C. of glacial acetic acid are added, the precipitate forming being more granular from such a mixture than when ether alone is employed.The solution is cooled in an ice-chest and bromine added, the flask being preferably left all night in the ice. This, however, is not essential for ordinary working. The liquid is filtered off' by the suction-funnel attached to il pump, the flask washed out with four successive portions of 10 C.C. of ether at 0" C., and the residue dried in the flask to constant weight. But even when ether at ordinary temperature is used, no considerable error is introduced. Varjous samples of pure linseed oil were examined by this method, with the following results : TA~<LE: VI. Sample. Oil taken. Weight of Precipitate. Percentage of Deprbsit. A 1 * 3226 0.3156 23.86 A 3.1005 0.7573 24.42 B 0.6792 0-1765 25.8 C 1 .0000 0.2480 24.8 c 1*0000 0.2500 25.0 A sample of walnut oil gave, in two determinations, 1.9 and 142 per cent.of bromo-compound. Poppy oil (four specimens) gave no deposit, nor did brazil-nut oil, maize oil, cotton-seed oil, olive oil, Japanese wood oil, OL' almmd oil. Mixtures of linseed oil and other oils gave percentages of bromine-compound in proportion to the percentage of linseed oil, as will be seen from the following table :316 THE ANALYST. Linseed Oil, Insoluble Bromide, Linseed Oil calculated Per Cent. Per Cent. from Bromide. Oils Used. Linseed A and walnut ... 69 16.6 69 9 , 9 9 ... 38.2 Linseed A and maize oil ... 52 9.3 38.1 12.4 50-8 9 ) 9 1 ..I 50.5 12.2 50.0 ?, 9 , ... 51.7 12% 51.6 I t will be seen from the above figures that the determination of the amount of the precipitate can usefully serve for testing the purity of unoxidized linseed oil.More extended investigation as to the variation in the proportion of the precipitate- yielding substance would, of course, be necessary, although as far as we have gone the variation appears to be small, Considerable interest is attached to the nature and composition of the insoluble bromine-compound. Froin its origin it cannot be identical with the acid hexa- bromide ; this is also shown by its melting-point, which is from 143.5" to 144" C., against hexabromide (177" C., Hazura; 180" C. to 181" C., Hehner and Mitchell). If it were hexabromo-linolenic glyceride, it would contain 62-28 per cent. of bromine. I t cannot be linolic tetrabromo-glyceride with 52-23 per cent.bromine, since maize oil does not furnish any insoluble compound, while the free acids readily yield large amounts of the acid tetrabromo-derivative. We have made a considerable number of bromine determinations, which gave remarkably constant results. In various pre- parations we found 56-38, 55.7, 56.38, 56.32, 55.55, 56.17, and 56-32 per cent. bromine. This percentage is too low for the hexabromo-glyceride and too high for the tetra- bromo-compound. Dr. Streatfield, of the Finsbury Technical College, was kind enough to make carbon and hydrogen determinations of a specimen of the material. Its ultimate composition was as follows : Carbon ... ... ... ... 32.97 Hydrogen ... ... ... . . . . 5-42 Bromine ... ... ... . . . 56-18 .lsh ... ... .. . . . . 0.99 Oxygen ... ... ... . . . 4.44 100.00 Calculated for the ash-free material, the coinposition is as follows : Carbon ... ... . . . ... 33.29 Broniine ... ... ... . . . 56-74 Hydrogen ... ... ... ... 5.48 Oxygen ... . . . . . . ... 4.49 100~00 We are inclined to attribute to the bromo-compound the formula C,7H,,06Br,,, which would require : Carbon ... ... ... ... 34.27 J3romine ... ... ... ... 56.11 13 y drogen ... ... ... ... 4.81 Oxygen ... ... ... ... 4-81 100~00THE ANALYST. 317 I t must be remembered that the substance, on account of its insolubility, could not be purified by crystallization. I n addition, the presence of mineral matter, probably derived from the oil itself, would tend to make deductions from the results still more uncertain.The percentage of bromine in the substance strongly points towards a mixed bromo-ester, and we suggest, very tentatively, the following formula : which, however, cannot be definitely accepted until a perfectly pure specimen has been examined. We are the more inclined towards a mixed glyceride formula, since the existence of such mixed esters has been fairly well proved in the case of butter- fat, and also because it is impossible to separate, even by persistently carried out recrystallization, the stearin from palmitin contained in animal fats. When, on the other hand, the glycerides are broken up by saponification, the separation is readily effected, and from the fatty acids separated from linseed oil a nearly pure hexa- bromide is readily obtained. Thus the acids of rape oil, which contains rapic acid, C,,H,,O, (which, unlike ricinoleic acid, does not appear to be a hydroxy-acid), yielded with bromine 3.6 per cent.of an insoluble bromo-acid containing 58% per cent. of bromine, and having a melting-point of 179" C. I t was, therefore, neither the hexa- nor the tetrabromo-compound of Hazura. Rape oil itself gave 0.9 per cent. of insoluble precipitate only; this was not further examined, The similar mustard-husk oil gave a fine granular precipitate amounting to 1.5 per cent. Some of the marine animal oils approach linseed oil in many of their properties, especially in their iodine absorption. It is interesting to note that the (impure) linolenic acid which we prepared from linseed oil had a marked odour of fish oil, and that pure linseed oil, when heated in steam, often emits a similar fishy smell.The free acids prepared from cod-liver oil gave on bromination a white pre- cipitate, which, when dried in the water-oven, became dark brown. I t amounted to 18 per cent., and contained 62.91 per cent. of bromine (theory requires for the hem- compound 63-31 per cent.). The air-dried substance had no definite melting-point, but decomposed below 200" C. Attempts were made to determine its melting-point ill a sealed tube, but these also yielded no results. The cod-liver oil itself (the glyceride) yielded with bromine an immediate precipitate, consisting partly of a solid substance, and partly of a heavy oil, which was difficult to separate from the former. Eventually a perfectly white solid substance was prepared, which amounted to 42.9 per cent. and contained 56.32 per cent. of bromine. I t had no sharp melting-point, decomposition taking place before fusion occurred. Cod oil behaved in an analogous manner, yielding 35-5 per cent. of insoluble compound, which was not further examined. Shark oil, similarly, gave 22 per cent. of a bromine.compouqd, and whale oil 25 per cent. The investigations of Hazura, both as regards the hydroxy-derivatives and the We have also made experiments with other classes of oils.318 THE ANALYST. bromine compounds of the unsaturated fatty acids, are of such great importance that it seems surprising so little has been done by other observers since the publication of his papers. We trust that our small contribution to the subject will cause others to pursue research in this direction. We have already indicated in several places starting-points for further work, and we are convinced that valuable additiom to our scanty knowledge of tho unsaturated fatty acids would result. If our supposition of the existence of a compound glyceride of the unsaturated fatty acids be confirmed, it would probably furnish an explanation of the different properties of oils possessing similar chemical constants.

ISSN:0003-2654    

DOI:10.1039/AN8982300310

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

318 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Pumpkin-seed Oil and its Adulterants. H. Poda. (Zeit. f i i y Unterszuh. der Nab. und Gemissmittel, 1898, 625-628.)-This oil (Olezim ciicicrbitcz) is used in Austria and Hungary for dietetic purposes in place of olive oil, to which it comes next in price. Its usual adulterants are linseed oil, sesame oil, cotton-seed oil, and rape-seed oil. Such sophistication can be detected by comparing the iodine and refractometer numbers, the specific gravity and melting-points of the fatty acids. Two samples of the pure oil prepared by the author gave the following results : Iodine Number. Saponificalio,l Jtefraotometer Niitnber a t 2 5 O c. Number. Cold pressed , . . 124.49-123.91 189-31-189.5 I 70.2 Hot pressed .. . 123.69-1 22.85 189-24-189-37 71.4 Cold pressed . . . 125.12-125.13 18993-189 -99 71.1 Hot pressed . . . 124.31-124-76 189 *56-189 4 2 72.0 oil I. { o i l II.{ limits : I n the author's opinion pure samples should give results between the following Bf elting- point of the hTumber at Specific Iodine Number Saponification Patty Acids. Gravity. according to I-Iubl. Xurnher. -_ Ueiinning. Ending: 25" c. 0.923-0.925 122*76-130*68 188.36-190*17 26.5-2885 28.4-29.8 70.0-72'5 H. H. B. S. Methoxgl Determination applied to the Examination of Resins, Balsams, and other Drugs. (Oesterreich. Chenz. Zeit., 1898, 253, 254, and 288- 290.)-The author has recently published a modification of Zeissel's method for the determination of inethoxyl (Monatshefte fiir Chemie, xix., 116 ; AKALYST, this vol., 297).I n the present paper he gives the methyl numbers of certain resins, balsams, and drugs as furnished by his method. I n the first of the following tables, G. Gregor.THE ANALYST. 319 Bamberger’s results are given side by side with those obtained by the author for the sake of comparison : RESINS AND BALSAAIS. N 0. 1. 3. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 33. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. Description of Resin or Balsam. ,4106 hepatica ... ... 1 zAinmoniacum . . . ... ,4106 lucida ... . . . ... I )Asafatida . . . ... ... Gum benzoin, Siani ... Gum benzoin, Sumatra ... Benzoin (almond), Sumatra Canada balsam ... Copaiva balsam ... Colophonium .Dammar . . . ... 7 Dragon’s blood . . . )Euphorbium . . . Pine resin ... ... Galbanum ... ... Copal ... ... I }Elemi ... ... }Gamboge ... . . . Guaiacuin . , . ... Gurjun balsam ... Laudanum . . . ... 1 Liquidam bar styrax I Jalap resin . . . ... Myrrh ... ... } G U ~ mastic ... ]Balsam of Peru . . , Scammonium . . . Sandarach . . . ... )Venice turpentine . . . Balsam of tolu . . . Olibanuni . . . ... ... ... ... ... ... .. . . I . ... ... ... ... ... ... ... ... ... . . . ... . . . * . . ... ... ... ... ... ... I .. -\ l -*! ... I -i ... ... ... ... ... ... -1 ...{ ..*{ ...{ . . . ... ... ... ... ... f ‘3. i ‘“‘I. ... ... \ **I ...{ ... ... ... Methyl Number. A -. Gregor. 4.2 0 8.6 9 11.9 6.9 43.4 25.5 20.3 20.1 20 0 0 0 0 0 27 -6 25.3 0 4.8 0 9.5 0 3.7 0 2.4 73.8 0 0 0 4.5 3.6 13-5 0 1.9 6.4 16.7 21.8 22.6 0 0 0 41.6 41.7 4.3 25.3 74.2 21.7 Bamberger 3.9 0 11 18 30 16.5 - - - - 13.3 0 0 0 0 0 33.8 0 0 0 0 3*7 0 83.8 0 0 0 13.6 0 5.3 14.4 - __ - - - _- - 0 0 0 46.8 - 28.5 16-2 4 84 13.2320 THE ANALYST.DRUGS. N O . 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. Description of Drug. f . . * \ f -9 }Araroba ... ... . . . ... ... )Guarana ... ... . . . ... ... ...{ ILactucarium . . . ... ... ... I ILupulin ... ... I ... ... ... ... * . . I 1 J ... \ Deadly nightshade leaves (Fol. belladonn. j . . . Gray Peruvian bark (Cort. Chin. fusc:j' Cinnamon, Chinese (Cort. cinnam. Chin,) }Foxglove leaves (Fol. digital. purp.) . . . Red Peruvian bark (Cort. Chin. rubr.) Calisaya bark (Cort. Chin. calis.) Cinnamon, Ceylon (Cort. cinn. Ceyl.) . . . ... ... . . . . . . ... I ''2 }Ipecacuanha root ... ... ... }Rhubarb (Rdx. rhei Chin.) ... ... ...( } Senega root (Rdx. Senegz) . . . ... ...{ hfethyl Number. Gregor. 19.2 22.2 1 1 1 1 1 1 19.4 22.3 24 4.5 4.9 4% 8.8 14.2 14-4 11.5 15.7 7.5 7.9 5.2 5.7 14.7 15 Bamberger. 18.8 19 4.2 8.3 5.5 H. H. B. S.

ISSN:0003-2654    

DOI:10.1039/AN8982300318

出版商:RSC    

年代:1898

数据来源: RSC

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320 THE ANALYST. TOXICOLOGICAL ANALYSIS. Micro-C hemical Identification of Spermatic Fluid Stains. C . Kippenberger. (geit. fiir Untewzich. der Nahr. uiad Gewussmittel, 1898, 602.) -The identification of traces of seminal fluid by means of the spermatozoa being not always possible, the author has investigated the method of Florence, depending upon the reaction with iodine and potassium iodide, with the view of its application to forensic work, and finds that this must be accepted with considerable reserve. The reagent is a, soiution of 1.65 grammes of potassium iodide and 2-54 grammes of iodine in 30 C.C. of distilled water. On mixing an aqueous extract of seminal fluid with this reagent, crystals of a dark-brown colour, varying in form from long-shaped rhombic tables to fine needles, are produced.The crystals vary somewhat in size, as well as in form, and are soluble in excess of the reagent, and in ether, alcohol, acids, and alkalies. The method of employing the test is as follows : An extract is first made by warming the stains or fluid with a little water on the water-bath. The extract is then acidified with hydrochloric acid, cooled, and dry ammonium sulphate added. which causes a separation to occur. The fluid is then filtered, a few drops of the filtrate mixed with the reagent and the mixture examined under the microscope.THE ANALYST. 321 The researches of Richter (Wz'eszey Klin. Wochenschm)?, 1897, 569) and of Lecco (Wiener Klin. Wochenschrift, 1897, 820) led to the supposition that the constituent giving rise to the reaction was cholin, either norinally present in small quantities or produced by the decomposition of lecithin, a recognised constituent of the seminal fluid. The author's experiments do not confirm this, but lead rather to the conclusion that the reaction is due to xanthine bodies and to creatinine.Further, the author is not able to confirm the statement of Florence that the reaction is only obtained with human seminal fluid. Experiments with the seminal fluid of bulls, rams, gazelles, camels, foxes, asses, dogs, amphibious animals, and birds, all resulted in the characteristic reaction, though slight differences were observable in certain cases. Contrary to Posner's experience, the author finds that seminal fluid which has become putrid still gives the reaction, and this applies also to old stains. With regard to other animal secretions, menstrual fluid, and, in one case, normal blood, gave a very similar reaction, which might be mistaken for the reaction with seminal fluid. Normal saliva and saliva from tuberculous persons gave negative results, as also did pus, unless mixed with blood. No reaction w-as obtained with urine, but, as this excretion contains sinall quantities of both xanthine bodies and creatinine, it is probable that the reaction would be obtained by the use of large quantities or of an extract. H. H. B. S.

ISSN:0003-2654    

DOI:10.1039/AN8982300320

出版商:RSC    

年代:1898

数据来源: RSC

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THE ANALYST. 321 ORGANIC ANALYSIS. J. C. Umney. (Phawz. Jour., 1898, 242.)-In the BritishiPharmacopceia of 1885 glacial acetic acid was described as containing '' nearly " 99 per cent. by weight of hydrogen acetate. In the new Pharmacopoeia (1898) the strength of the acid is given as 99 per cent., and it is provided that the acid shall have a specific gravity of 1,058, and that it shall remain solid until the temperature rises above 60" F. (15.5" C.). The author points out that this solidification-temperature is not in agreement with the percentage. Rudorff (Pharrn. Jour., Series 3, ii., 241) states that the strength of glacial acid can be estimated with greater accuracy by determining the freezing- point than by titration with alkali, and gives the following table : Solidifoying Point.C. The Freezing-point of Glacial Acetic Acid. 100 Parts of Mixture. Containing 0.0 of water ... ... ... 16.7 Y , 0.497 7 7 ... ... ... 16.65 9 , 0.99 7 7 ... ... ... 14.8 , J 1.477 9 7 ... ... ... 14.00 Y Y 1.961 7 , ... ... ... 13.25 From this it is evident that glacial acetic acid containing actually 99 per cent. oL hydrogen acetate does not remain solid above 14-8" C. According to the U.S.A. Pharmacopaeia, glacial acid contains 99 per cent. of absolute acid, solidifies somewhat below 15" C., and becomes liquid again at about 15" C. The commercial importance of this apparently trivial point is shown by the fact that glacial acid is admitted into New Zealand at an ad vaZorern duty of 20 per cent.,322 THE ANALYST. but if the acid falls below the British Pharmacopmia standard, 5d.per lb. duty has to be paid, or about five times as much as the proper duty. The New Zealand Customs have hitherto 'based their decision as to the strength of the acid on its liquefying- point after freezing, and regarding the statement of the British Pharmacopoeia as absolutely accurate, they charge the 5d. per lb. duty on all acid melting below 15.6" C. C. A. M. Estimation of Formic Acid in Presence of Acetic Acid and Readily Oxidisable Organic Bodies. (Ann. et Rev. chim. Analyt., vol. iii. is], pp. 255-260.)-The inetliod is based on the reduction of mercuric acetate to the mercurous salt. I n the case of liquids containing acetic and formic acids, the total acidity is first determined in terms of the former. If the relative proportion of formic acid is very low, the liquid is diluted until the acidity measures 20 to 30 per cent.; but if the ratio is as 1 : 20 of acetic acid, dilution to 2 per cent. of acidity is necessary. Ten C.C. are then taken, inixed with 20 to 30 C.C. of a 20 per cent. solution of mercuric acetate, and made up to 100 C.C. with water, the whole being heated t o boiling-point within seven or eight minutes, and then 'immediately set aside to cool until the following day. The brilliant white crystals of mercurous acetate deposited are filtered through glass wool, brought on to the filter, then washed with 95 per cent. alcohol, acidified with 2 per cent. of glacial acetic acid (to prevent decomposition of any residual mercuric acetate), and finally with neutral 95 per cent.alcohol. After removing the alcohol by anhydrous ether, and evaporating the latfer, preferably in vacw, the precipitate is dissolved as rapidly as possible in nitric acid diluted with its own volume of water, and an aliquot part of the solution is precipitated with sodiunl chloride, the mercurous chloride being then weighed after drying at 100" C. The weight multiplied by the factor 0.0976 gives the corresponding amount of formic acid. Drying should not be prolonged more than is absolutely necessary, or a loss of weight, due to volatilization, will occur. When the liquid under examination contains alcohol in addition to formic acid, 2 C.C. of glacial acetic acid must be added to the test sample before adding the mercuric acetate, to prevent precipitation of the latter.Should the proportion of alcohol be relatively high, the crystals of mercurous acetate formed may be granular and dense, instead of the fine scales obtained in the first-named case. If both alcohol and acetic acid (the latter in sufficient amount) are present in the liquid, then no further addition of this acid is necessary. The method is also applicable in presence of acetic and formic aldehyde, and is recommended by the author for the estimation of formic acid in natural spirits and commercial formaldehyde, as well its for the titration of formaIdehyde after oxidation. A. Leys. c. s. A Very Sensitive Test for Bromine in Urine. A. Jolles. ( Z e d . anal. Chem., 1898, xxxvii., 439-440.)-This test is based on the fact observed by the author that, on treating a hot acid solution of urine with permanganate, any bromine CO~pouQdsTHE ANALYST.323 present are decomposed with the liberation of free bromine, which can be readily identified by means of y-dimethyl-phenyl-diamine paper. This is prepared by dipping filter-paper into a solution (0.5 gramme in 500 c.c.) of the hydrochloride of p-dimethyl-phenyl-diamine, and leaving it to dry. This substance gives with bromine a red colouring matter, the probable composition of which is NH : C,H, : N(CH,),Br, and which, in the solid condition, has a metallic, green glittering appearance. The reagent-paper, when brought into contact with bromine vapour, gives a violet colora- tion in the centre, while the edges are blue, gradually changing into grey, and finally into brown.The reaction is extremely sensitive, and is capable of detecting 0.001 gramnie of sodium bromide in 100 C.C. of urine. The corresponding iodine reaction is much weaker, and the coloration of the paper (yellowish brown) is quite distinct, so that traces of bromine cztn readily be detected in the presence of large quantities of iodine. Chlorine, too, gives a very feeble reaction, which does not interfere with the bromine reaction. The test is made in the following manner: 10 C.C. of the urine are acidified with sulphuric acid, and an excess of potassium permanganate is added. The flask is warnied on the water-bath, and a moistened strip of the reagent-paper placed in the neck of the flask. The fluorescein-paper reconimended by Baubigny (ANALYST, this volume, 23) is also very suitable for the detection of bromine liberated from urine by means of permanganat e.C. A. M. On the Coagulation of Albumin. G . Halphen. (Jozw. P h ~ i ~ m . G h h . , 1898, viii., 173-175.)-1n order to assist the coagulation of albumin in solutions of pepsin and in urine, the author has made experiments on the addition of s.mmoniurn salts. He finds that salts of ainnionium, such as the chloride and the citrate, accelerate the coagulation of albumin. A sufficient quantity of a 10 per cent. solution are added to the albuminous solution before boiling, and the precipitate collected on a weighed filter, washed, dried, and weighed. C. A. M. The Detection of Pyramidon (Dimethyl - amido - antipyrine) in Urine. A. Jolles. (Zeit. c m i l . Chenz., 1898, xxxvii., 441-442.)-Pyraniidon is an antipyrine- derivative which has recently been prepared and recommended by Filehne ( B e ~ l i n lilliiz.Wocheizs., 1896, 48). I t gives a characteristic bluish-violet coloration with ferric chloride, which, like the analogous red colour given by antipyrine, rapidly disappears. A fugitive violet coloration is also produced by it on treatment with a nitrite and sul- phuric acid. The test which the author has worked out for its detection in urine is based on the fact that it is oxidized by halogens with the production of a violet colora- tion. The blue colour yielded with an alcoholic solution of bromine soon fades, but that obtained with an alcoholic solution of iodine changes after some time to red. Hydrogen peroxide gives a blue colour on warming ; the action of perinanganate is too energetic, and a colourless compound results which no longer reacts with halogens.Weaker oxidizing reagentls, such as arsenic acid and alkaline copper solution, do not give a blue coloration. The behaviour of pyramidon towards the halogens is to be324 TEE ANALYST. chiefly attributed to the presence of the dimethyl-amido group, which, as has often been observed, readily reacts with oxidizing agents. Most of these reagents give no characteristic results with pyramidon in urine. Ferric chloride produces the violet colour, but less markedly than in aqueous solution. On the other hand, alcoholic iodine is very sensitive, and by testing the urine with a, very dilute solution (10 per cent. iodine solution diluted with 9 volumes of water) there is formed on the surface of the liquid a sharp violet red ring, which on standing changes to reddish-brown. The author finds that when pyramidon is taken in doses of 0.2 gramme twice a day it is readily detected in the urine by means of this test.C. A. M. Detection of Carbon Monoxide in Confined Air. F. Jean. (AWL et &?v. Chiin. Andyt., vol. iii. (IS], pp. 260, 261.)-The Marmet permanganate reagent being liable to reduction by other agencies than carbon monoxide present in samples of air, the author prefers to draw the air through a tube containing cuprous chloride solution, which, in presence of the monoxide, deposits a characteristic red precipitate. c. s. The precipitate thus formed is according to Berthelot (AIZU.Cliem. Phnrm., xcviii., 392) prohably Cu,CI,.CO. 2H,O. -ED. The Volumetric Estimation of Certain Alkaloids as Higher Periodides. A. B. Prescott and H. M. Gordin. (Jour. Anw. C ~ W L . Soc., 1898, xx., 706-724.)- By adding a solution of iodine in potassium iodide to a solution of an alkaloidal salt, the lowest periodide (in most cases a tri-iodide) is generally formed; if the iodine be kept in excess the highest periodide is formed, Of these latter some are stable and can be recrystallized, while others readily decompose in solution into free iodine and lower periodides. Atropine enneaiodide belongs to the first class ; strychnine and brucine heptaiodides to the second. The only periodide of morphine which the authors could obtain was the tetraiodide already prepared by Jiirgensen.Aconitine yielded (probably) a tri-iodide and a heptaiodide. The formuke and iodine factors of the higher periodides so far determined are : Alkaloid Factor of 1 c. c. of - Iodine Solution. Itatio of Alkaloid N 10 to 1 of Iodine. Atropine, C17H,,N0,,.H 1.1, ... 0.2849 . . . 0.0036048 Strychnine, C,,H,,N20,. HI. I,j ... 0.4390 . . . 0.00555467 Brucine, C,:,H,,N ,Og€€I.I,j ... 0.5179 . . . 0.00655299 Morphine, C17HI$J03.HI.Is ... 0.74918 . . . 0.00947937 Caffeine, C,HIoN,O,.HI.I, (Gomberg) 0.3834 ... 0.00485 The general method to be followed in estimating the strength of an aqueous solution of an alkaloidal salt is as follows : To about 10 C.C. of TG iodine solu- tion, diluted with a little water, is added 1 C.C. of the acidulated alkaloidal solution, and the mixture well shaken for a few minutes.If the clear supernatant liquid does not retain a dark-red colour after the separation of the precipitate, the alkaloidal solution is too strong _and must be diluted. When the right dilution has been ascertained, the acidulated alkaloid solution is made up to definite volume, and 10 to 15 C.C. of it run from a burette into a graduated vessel containing 25 to 30 C.C.THE ANALYST. 325 of ff iodine solution, diluted with a little water. The mixture is made up to definite volume and shaken, until the supernatant liquid is clear and of a dark-red colour. If not, the determination must be recommenced with a larger excess of iodine, as an addition of more of the iodine solution to the same mixture is out of the question, since the lower periodides when once formed might not take up more iodine. With iiiorphine, which only forms one periodide, this precaution is unnecessary, When perfectly clear, an aliquot portion of the liquid is filtered off and the excess of iodine determined with standard sodium thiosulphate.Thus the quantity of iodine multi- plied by the '( ratio of the alkaloid to 1 of iodine '' gives the quantity of the alkaloid in question. The authors state that they have obtained satisfactory results by this method, in the determination of the total alkaloids in nux vomica and belladonna after extracting them with various solvents. They also confirm the accuracy of Gomberg's method of determining caffeine (ANALYST, vol. xxi., 193). c. A. ni. Notes on Taka Diastase.W. E. Stone and H. E. Wright. (Jozsr. Amer. Chem SOC., 1898, xx., 639-648.)--The authors have made a series of experiments on the action of taka diastase {ANALYST, this volume, 108) on potato-starch as compared with that of malt diastase. They found that its action at the outset was more rapid, the blue colour of the starch with iodine changing almost immediately to reddish and violet tints, while the starch paste was very rapidly liquefied. On the other hand, the complete conversion of the starch into compounds which no longer gave colour reactions with iodine was effected much earlier by the malt diastase, this final result being scarcely attained by the taka diastase after several hours. Parallel experi- ments, in which the solutions were examined with the polarimeter at stated intervals, showed that the products of the action of taka diastase had invariably a lower specific rotation than those from malt diastase, which the authors attributed to the inore rapid conversion into maltose.These results being unfavourable to the use of taka diastase in place of malt diastase in the quantitative determination of starch, the authors made further experi- ments with different materials in which a starch estimation is commonly required. One gramme each of air-dried finely-ground wheat, maize, and potato were heated to the boiling-point during thirty minutes with 50 C.C. of water. After cooling to 60" C., 10 C.C. of malt infusion were added to each, and the temperature maintained at 60" C. A second series was prepared in the same way, to each of which was added 0.05 gramme of taka diastase, and a third series in which the quantity added was 0.1 gramme, the temperature being maintained at 40" C.After four and a half hours all were tested with iodine, and it was found that in those treated with malt infusion the whole of the starch had disappeared from the potato, while the wheat and maize still showed traces under the microscope. I n those treated with taka diastase all showed an abundance of unchanged starch. After seven hours the samples treated with malt infusion were quite free from starch, but the taka diastase samples still contained a large quantity, and even after an additional twelve hours' treatment the starch reaction had not disappeared.326 THE ANALYST.As a further test, duplicate quantitative determinations were made of the starch contained in a specimen of air-dried wheat, the solvent in the first instance being a freshly-prepared infusion of malt, and in the second a solution containing 0.05 gramme of taka diastase. I n each case the sugar was determined by titration with Fehling’s solution, and the results calculated to starch. The treatment with malt extract gave 55.46 per cent. of starch, while the determination by means of taka diastase gave 52-94 per cent. From these experiments, the authors conclude that under the usual conditions of the analysis taka diastase is unsuitable for the quantitative cleterniination of starch. C. A. M. Tho Quantitative Estimation of Proteids. H. Schjerning.. (Zeit. anal.Chenz., 1898, xxxvii., 413-422.)-1n this paper the author sums up the results of his previous communications, and embodies them in a complete method for the estimation of proteid substances in solution (cf. Zeit. a m l . Chena., xxxiii., 263 ; xsxiv., 135 ; xxxv., 285; and ~ T A L Y S T , 1898, 105 and 185). The reagents required are : 1. A solution of tin chloride prepared by dissolving 50 graninies of tin in a weighed flask containing a sufficient quantity of boiling concentrated hydrochloric acid and a little platinic chloride. The solution is evaporated down to about 130 grammes, made up to a litre, and filtered. 2. A solution of normal lead acetate containing about 10 per cent. of the salt, and 10 to 12 drops of 45 per cent. acetic acid in a litre. 3. A 5 per cent.solution of mercuric chloride. 4. Pure, dry ferric acetate. 5. Dilute acetic acid containing 15 C.C. of 45 per cent. acid in a litre. 6. A solution of pure uranium acetate (about 10 per cent.), free from ammonia. 7. Pure, crystallized magnesium sulphate. 8. A solution of ordinary sodium phosphate, containing 0.4 per cent. of the 9, X solution of calcium chloride (about 10 per cent.). The solution of the proteids is first diluted so that 10 C.C. contains a quantity of total nitrogen corresponding with about 5 C.C. of decinormal acid. Under some conditions the precipitations are readily made, but when the solution contains little or no ash, it is necessary to add mineral matter (solutions 8 and 9). I n order to determine whether this addition is required, the following test is made: If the number of C.C.of the probeid solution, which correspond with about 10 C.C. of ;G acid, do on boiling not cornpletely precipitate the iron from a solution of 0.8 gramrnes of ferric acetate dissolved in 40 C.C. of dilute acetic acid (reagent 5) and 50 to 100 C.C. of water, the proteid solution must be regarded as poor in ash, and the precipita- tions by tin, lead, and iron must be made after the addition of mineral matter (reagents 8 and 9). Tlie Tiu Chloride Pr.ecz~itutioia.--,lbout 5 C.C. of the tin chloride soluliion (reagent 1) are added to 25 C.C. of the proteid solution. After stirring well, the crystallized salt.THE ANALYST. 327 beaker is covered with a glass and left for from six to twenty hours. The precipitate is then collected on a filter and washed with cold water.If the proteid solution is poor in ash, 10 C.C. of calcium chloride solution (reagent 9) are added before the tin chloride, and the precipitate washed with a cold 1 per cent. solution of calcium chloride. The Lead Pwcipitation.-To 25 C.C. of the proteid solution are added a sufficient amount of the lead acetate solution (No. a), the amount varying with different substances. Care must be taken that the excess of lead is not too great, or part of the precipitate may be redissolved, After adding the reagent, the liquid is boiled, and the precipitate collected and washed with cold water. If the proteid solution contains little ash, sodium phosphate solution (No. 8 ) is added in the proportion of about three volumes to each volume of the lead acetate solution used, before boiling.Since the lead precipitate is somewhat soluble in the precipitating reagent, correction is necessary, which the author has determined experimentally to correspond with 0.15 C.C. of & acid for each 100 C.C. of filtrate and washings. The Mercuric Chloride Precipitatioiz.--Five C.C. of the mercuric chloride solution (No, 3) are added to 25 C.C. of the proteid solution, the liquid allowed to stand from four to twenty hours at the ordinary temperature, the precipitate filtered off and washed with a cold 0-5 per cent. solution of mercuric chloride, and the nitrogen it contains determined by Kjeldahl's method. The Iron P?.ec?2-'itntio72.--0.~ gramme of ferric acetate is dissolved in 40 C.C. of the dilute acetic acid (reagent 5), and 50 to 100 C.C.of water in a beaker, and the solution heated to boiling, with constant stirring. 20 C.C. of the proteid solution are then added, and the liquid again brought to the boiling point. The precipitate is filtered off and washed three or four times with boiling water. The filtrate should be quite clear, and if this is not the case, an addition of from 15 to 25 C.C. of the sodium phosphate solution should be made immediately after the second boiling, the liquid being in the meantime stirred and kept boiling. With a little practice the right amount of sodium phosphate can be estimated. 20 C.C. have no injurious effect if these directions are followed, and only in exceptional cases is it necessary to add greater quantities (at most 25 c.c.). The Uraitium Precipitation.-25 C.C.of the proteid solution are mixed with 20 to 25 C.C. of the uranium acetate solution, the liquid heated to the boiling-point with constant stirring, and allowed to stand for some hours, or until the following day, in a dark place. The precipitate is washed with a cold 1 to 2 per cent. solution of uranium acetate. The correction necessary for the solubility of the precipitate corresponds with 0.10 C.C. of Fv acid for each 100 C.C. of filtrate and washings. The Magnesium Szdphate Precipitation.-Five or six drops of 45 per cent. acetic acid are added to 20 C.C. of the proteid solution, and the beaker placed in a water bath, which is kept a t a temperature of from 33" to 36" C. From 18 to 20 grammes of finely powdered magnesium sulphate (MgSO, + 7H,O) are added, with constant stirring, and the liquid allowed to stand for thirty minutes to one hour at the ordinary temperature, a stir being given from time to time.The precipitate is filtered off and washed with a cold saturated solution of magnesium sulphate containing 4 to 5 grammes of 45 per cent. acetic acid per litre.328 THE ANALYST. The relation of the several precipitates is given in the following scheme : Precipitate. Contains the Proteids. Precipitate. Contains the Proteids. Albumin I Albumin I1 Propeptone b - Albumin I1 Uranium Acekate = d Denucle'in Albumin I Albumin I1 Denuclein Magnesium Sulphate . Albumin I1 I Propeptone Propep t one I Tin Chloride = CL Lead Acetate - [ Mercuric Chloride Albumin I Albumin I j - Denuclein p,:z I Ferric Acetate = c The quantity of the different groups of proteids can thus be readily determined, as was shown in a former communication.The proteids precipitated by lead acetate and mercuric chloride are identical, but as the mercury usually gives more satisfactory results than the lead, the latter need only be used in exceptional cases. The author concludes his paper with tables of the results obtained with solutions of various kinds of proteids which are very similar to those given in his former paper. C. A. M. The Analytical Methods of distinguishing the Nitrogen of Proteids from that of Amides. J. W. Mallet. (Bulletin 54, United States Department of Agricul- ture.)-The author has investigated various methods which have been proposed for separating these two classes of bodies, such as dialysis; interaction with nitrous acid ; treatment with permanganate in presence of free alkali or acid ; with sodium hypobromite ; behaviour with cupric hydroxide ; precipitation by alcohol ; the behaviour of several new or little-used reagents, such as phenol, trichlor-acetic acid, form- aldehyde, etc.; of tannin; and also that of phosphotungstic acid. This last reagent proved in most cases the most reliable one, and when applied under proper conditions afforded satisfactory results, though in certain cases tannin was found to be the preferable reagent. Some of the special facts on which the application of phospho- tungstic acid depends are new, and the particular use made of these points of behaviour has not been hitherto described.The assumptions of Stutzer, that the proteids and allied suhstances are precipitated by phosphotungstic acid, and that the amides are not precipitated, must be qualified. Thus peptones are incompletely precipitated, while flesh-bases, such as creatine, creatinine, etc. , are fully precipitated. Some substances also of an amidic nature give precipitates which are almost insoluble in water, but the solubility of which is much increased by rise of temperature. It was found that the substances experimented with might be divided into the three following classes : ( a ) Those which, even in pretty strong solutions, give no precipitate with pliosphotungstic acid. ( b ) Those which are precipitated in strong solutions, the precipitate redissolving with more or less ease on heating the liquid (or on treating the precipitate with hot water) and reappearing on cooling. ( c ) Those which are precipitated, the precipitate not being sensibly soluble, andTHE ANALYST.329 the supernatant liquid remaining clear on being heated along with the precipitate and subsequently cooled, Under the first head fall glycocine, alanine, leucine, asparagine, aspartic acid, tyrosine, and allantoin ; under the second, glutamine, creatine, creatinine, hypo- xanthine, carnine, and urea. The precipitate given by peptone becomes clotted on heating, and dissolves to a considerable extent, being reprecipitated on cooling. Under the third head are included egg-albumin, fibrin, casein, legumin, globulin, vitellin, myosin, syntonin, hzmoglobin, albumose, gelatin, and chondrin.The following amidic substances yielded precipitates with phosphohungstic acid, which were found to be soluble in hot water in the following proportions : That from betaine, 1 part in 71 parts of water at 98.2" C . ; creatine, 1 : 107 parts at 98.1"; creatinine, 1 : 222 at 97.9" ; hypoxanthine, 1 : 98 at 97.6"; carnine, 1 : 132 at 98.4". I t seemed possible, by precipitating with phosphotungstic acid, and washing the precipitate with hot water, to separate the ainidic substances from all proteid and proteid-like bodies, except the peptones. These last are, according to most authori- ties, completely precipitated by tannin ; hence this reagent disposes of the one case unprovided for by phosphotungstic acid. The precipitants employed were 5 and 10 per cent.solutions of phospho- duodecitungstic acid in 2.5 per cent. hydrochloric acid, and 5 and 10 per cent. aqueous solutions of tannic acid. It is stated, for the sake of simplicity, first as applied to the analysis of meat, raw or cooked, and the variations required in the examination of other classes of food materials are given afterwards. A carefully selected and accurately weighed sample is to be ground in a glazed porcelain mortar with as much sharp-edged siliceous sand, previously heated to redness with free exposure to air, or with as much hard glass in small, sharp splinters similarly ignited, as will suffice to thoroughly subdivide the tissue and reduce it to the condition of a smooth pulp. Of this pulp, very carefully mixed, so as to insure uniformity, two aliquot parts are to be taken. I n one the total nitrogen is to be determined by the well-known Gunning-Kjeldahl process, using a rather large proportion of sulphuric acid, so that no previous drying of the sample is needed.The other part is to be digested with cold water, filtered on to a nitrogen-free filter, and the residue washed on the filter with water at the same low temperature as long as it gives up soluble matter in sensible amount. Cold water is used to avoid action on and extraction of the gelatiuoids. Creatinine is quite easily dissolved, as is also sarcosine ; creatine with tolerable facility. Yanthine, hypoxanthine (1 : 300), and carnine (1 : 312), are less soluble. The filtrate is then to be slightly acidified with acetic acid, heated to about 90" C., and again filtered from any coagulum.A little more sand or pulverized glass may with advantage be stirred in before bringing it on to the filter the second time, To this second filtrate is to be added an acidified solution of phosphotungstic acid as long as a precipitate continues to form, avoiding any very large excess of the reagent. With a moderate amount of sand or pulverized glass added, to prevent the formation of a dense clot, the liquid and precipitate are to be heated to about 90" C., The method proposed is given below nearly in the author's own words.330 THE ANALYST. filtered, and the precipitate washed thoroughly on the filter with water at about the same temperature. Assuming now that nitrogen is present in the sample under examination only in the two forms of proteids and simpler amidic compounds, the three filters used and their contents are to be submitted to the Gunning-Kjeldahl process.By subtraction of the nitrogen found from the total nitrogen previously determined, the amount of this element present in the simpler amidic compounds will be obtained. I n cases involving the presence of ammonia or its salts, nitrates, or alkaloids, the nitrogen occurring in these forms must be deducted from the total nitrogen before recording the residue as nitrogen of the simpler amides and amido-acids. I n like manner a separation of lecithin, when present, may be effected by the use of ether as a solvent, followed by a mixture of ether and alcohol, in order to secure a complete extraction.A determination of phosphorus is made the basis of a calculation of lecithin-nitrogen, and this is in turn subtracted from the total nitrogen found. When peptones are present, these are to be precipitated by tannic acid from the solution which has been acidified with acetic acid and heated. After this has com- pletely cooled down, and before adding phosphotungstic acid, the filter on which the tannic acid precipitate is collected and washed with cold water is, with its contents, to be submitted to the modified Kjeldahl process, and the nitrogen obtained reckoned as part of the proteid nitrogen. The several filters and precipitates from which the proteid nitrogen is obtained may either be treated separately by the Kjeldahl process, or, preferably, may all be brought together and submitted to this process in a single operation.If t'he latter course be pursued, it will be well to introduce each filter with its contents a3 soon as washed into the strong sulphuric acid, so as to avoid any possible decomposition and loss of nitrogen as ammonia until all the filters have been brought together and the moist combustion process can be proceeded with. When proteoses are present, it may be well to make a check determination of their amount by saturation of the aqueous solution (after acidification with acetic acid, heating and subsequent cooling) with zinc sulphate, determining nitrogen in the precipitate so formed by means of the Kjeldahl process, When gelatinoids are present, as may be the case with soups, stews, and meat extracts, hot water may be used at once for solution or washing the original material, and this with the advantage of facilitating the extraction of the less soluble simpler ainides and amido-acids.These are, as a rule, more easily dissolved in the presence of a little free acid; hence acidification at an early stage of the treatment is advan- tageous. In a case in which tyrosine might be present, as in some vegetable materials, and possibly among unabsorbed residua of food, the use of hot water and the presence of free acid would greatly increase the solubility of this substance. I n food of vegetable origin where much starch is present it will be better to avoid the use of hot water at first, so that the solution may not be loaded with viscid material, rendering filtration difficult.I n all cases in which the food material to be examined is already fluid from the presence of water-as, for instance, soup, milk, and the like-filtration will of courfie at once be resorted to, being almost always much facilitated by the addition of sandTHE ANALYST. 331 or pulverized glass, and only such further quantity of water will be used as is required for washing the undissolved matter left upon the filter. I n the presence of fat in large quantity it may be well first to remove this, or most of it, by extraction with ether. The simpler amidic substances are, as a rule, insoluble in ether, but by way of precaution the ethereal solution of fats might be shaken up two or three times with acidified water, and the watery fluid evaporated and tested for nitrogen, I n regard to the method of reporting results, the most important point is the separate statement of the amount of nitrogen present in the form of proteids and their congeners, and in the form of the simpler amides and amidc-acids.But in attempting to calculate from the nitrogen found under these heads the actual amount of the proximate nitrogenous constituents of the food material examined, the difficulty arises as to what factor should be used for multiplying the nitrogen found in each case. The author suggests the following factors : For proteids and allied substances, multiply nitrogen found by the ordinary factor 6.25. For flesh-bases and simpler amides of animal origin in food-materials, multiply by 3.05.For simpler amides and ainido-acids of vegetable origin in food materials, multiply by 5.15. For mixed amidic constituents of unabsorbed solid residua in digestion experi- ments, multiply by 9.45. As a matter of general practice, it is recommended that in all statements of the results the actual amounts of nitrogen obtained should be given, so that if, with further knowledge of the nature of the proximate nitrogenous constituents present, the factor used in calculation be subsequently changed, the original experimental work will still retain its value. W. J. S. Quantitative Estimation of the Citter Principles in Hops. C. J. Lintner. (Zeits. fiir d. ges. Brazizceseii, vol. xxi. [31], pp. 407-410.) I n order to overcome the inconveniences arising in the ordinary gravimetric method for the extraction and drying of the bitter constituents, the author recommends titration of the extract with decinormal alkali, ut;ing phenol-phthalein as indicator. Ten grainrnes of hops are placed in a half litre flask, and extracted by means of 300 C.C. of petroleum spirit (B. P. 30" to 50" C.) for eightJ hours, under an efficient reflux condenser, the flask being immersed to a depth of 2 to 3 c.m. in water kept at about 50" C. When the operation is completed, the contents of the flask are cooled to 17.5" C., made up to 505 C.C. (=500 C.C. of liquid) with petroleum spirit, and filtered into a stoppered flask. This should be performed as quickly as possible, to prevent the extraction of y-resin, which would falsify the results. One hundred C.C. of the filtered extract are titrated with alcoholic (96 per cent. by volume alcohol) decinormal potassium hydroxide. To facilitate the admixture of the liquid with the reagent, 80 C.C. of 96 per cent. by volume alcohol are added, and332 THE ANALYST. 10 drops of phenol-phthalein (I : 100) solution are used as indicator. The reagent is added until the yellow colour of the liquid shows a decided red tinge, the end point being easily distinguishable after a little practice. A blank titration must be made t o ascertain the volume of alkali consumed in neutralizing the petroleum spirit and alcohol. The resulting values multiplied by 0.4 express the content of bitter principle in ternis of lupulinic acid. c. s.

ISSN:0003-2654    

DOI:10.1039/AN8982300321

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

332 THE ANALYST. INORGANIC ANALYSIS. The Determination of Technically Available Molybdenum in Molyb- denum Glance. H. Borntrager. (Zed. nmZ. Chem., 1898, xxxvii., 438.)-Most of the methods employed for the determination of molybdenum give the total amount of the metal, and not that available for technical purposes, which, however, is most frequently required in a valuation of an ore. I n the following method described by the author only the readily available molybdenum is estimated : About 1 gramme of the molybdenum glance is digested in an Erlenmeyer flask for about two hours with 25 C.C. of strong nitric acid, until all the molybdenum has been converted into molybdic acid. Ammonia is then added to dissolve the molybdic acid and the liquid filtered. The residue is again digested with nitric acid and treated with ammonia, and the combined filtrates mixed with nitric acid and evaporated to dryness.The residue, consisting of molybdic acid and ammonium nitrate, is digested with dilute alcohol (50 per cent.), in which the ammonium nitrate is soluble. The molybdic acid left behind is collected on a weighed filter, washed with 50 per cent, alcohol, dried, and weighed; or preferably it is dissolved in 50 C.C. of normal ammonia, and the solution titrated with normal sulphuric acid, the difference being calculated into molybdic acid. CA A. M. A New Volumetric Method for the Determination of Copper. R. K. Meade. (JozLru. ,-lm~. Chenz. Soc., 1898, xx., 610-613.)--The following method is claimed to be superior to the iodine and cyanide methods, both in rapidity and accuracy.The copper is brought into solution as sulphate, the greater part of the free acid neutralized with ammonia, the solution warmed, an excess of sulphurous acid added, followed by an excess of ammonium or potassium thiocyanate. The solution is filtered through asbestos with the aid of a filter pump, and the precipitate and filter, after being well washed, are heated in a beaker with a solution of caustic potash or soda. The reaction which takes place is shown in the equation 2CuSCN + SIC013 = CU,O + H,O + SKSCN. The oxide is filtered off on asbestos, and washed with hot water. The pre- cipitate and filter are again placed in the same beaker, and an excess of ferric chloride or ferric sulphate (free from nitric acid, free chlorine, or ferrous salts) added, together with a little dilute sulphuric acid.The solution is then titrated with standard permanganate, and the iron equivalentTHE ANALYST. 333 of the permanganate used, multiplied by 1.125 gives the weight of copper in the sample. Instead of sulphurous acid, acid ammonium or sodium sulphite may be used to reduce the copper. Since copper is the only metal precipitated as thiocyanate from an acid solution, the presence of arsenic, antimony, bismuth, or zinc will not affect the results. The caustic alkali solution used to convert the cuprous thio- cyanate into cuprous oxide must not be too strong, or some of the copper will go into solution. The results obtained by this inethod in the analysis of a sample of pure copper were in close agreement with those of an electrolytic determination.The compara- tive figures given by the two methods with specimens of copper ore are shown in the subjoined table : The author recornmends a solution of about semi-normal strength. Per Cent. Sample. Grtlminea. 1. Chalcopyrite I. ... 1.0 2. ,> ... 1.0 3. Chalcopyrite I T . . . . 9 .o 4. 2 9 ... 9.0 5. Malachite ... . I . 1.0 6. 9 , ... ... 1.0 7. Tetrahedrite ... ... 1.0 8. I ) ... ... 1.0 copper by 19.85 19-70 6-16 6.21 36.19 36.19 21.05 20.90 Th ioc.yun:~te-per.m3ng.,znate Method. Copper by Electrolytic Jkthod. 19.95 19-86 6.37 6.30 36.10 36.15 91-06 21.18 The author states that after the ore has been brought into solution duplicate analyses can easily be made in from half to three-quarters of an hour.C. A. M. The Determination of Uranium. H. Borntrager. (Zcit. anal. C ~ ~ C ~ I L . , 1898, xxxvii., 436, 437.)-A. Patera described a method of determining uranium which consisted in dissolving the ore in nitric acid, diluting with water, saturating the solution with sodium carbonate, boiling and filtering. off', and washing the precipitate. The filtrate, which besides uranium contained only traces of other metals, was mixed with sodiuin hydroxide, and the precipitate washed, ignited, and weighed as Na,0.2U0,j, coi-responding with 88.3 per cent. of UO,. While this method gives good results with rich ores, it is otherwise with ores containing only 33 to 65 per cent. of UO::, and especially with uranium sand, which contains onlyfrom 8 to 18 per cent. In such cases considerable quantities of silica are dissolved, and are weighed with the urzzniuiri.To obviate this the author recommends dissolving the ignited precipitate in hydrochloric acid, filtering off the silica, and again precipitating the uranium with sodium hydroxide or ammonia, and weighing it as Na,0.2U03, or UO:;. The method is illustrated by the following results : 1. 11. 111. 1v. V. Uranium ore taken, gramnies . . . ... 1.606 1,198 1.123 1430 2.180 Crude sodium uranate, grammes . . . 1.190 0.920 0.750 1.155 1.800 Containing SiO,, gramnies . . . ... 0.026 0.040 0.025 0.037 0.040 UO, precipitated with NH3, grammes 1.010 0-780 0,622 0.857 1.325 Per cent. of UO, ... ... . . 62.90 65.70 55-40 59.90 61.00 C. A. M.834 THE ANALYST. Determination of very small Quantities of Phosphoric Acid.A . Jolles and F. Neurath. (Moizntshefte .fiir Clzemie, 1898, xix., 5.)-A solution of potassium molybdate is first prepared by dissolving 8 grammes in 50 C.C. of water, and adding 50 C.C. of pure nitric acid of 1.2 specific gravity. One hundred C.C. of this solution are required for 0.1 gramme P,O,, so that for any quantity below 0.001 gramme 1 C.C. is suficient. Twenty C.C. of the solution to be tested, which must be clear and colourless, are placed in a test-glass, 1 C.C. of the molybdate solution added, and the whole warmed to about 80" C. The colour is then compared with that produced under exactly similar conditions by known quantities of sodium phosphate --e.g. , 0.001, 0.00075, 0-0005, etc. The following results show the degree of accuracy obtainable : P205 taken, Gramme.Y,Oj found, Gran1mn.e. Difference, Gramme. 0.001 0.001 0 0.00085 Between 0.001 and 0.00075 nearer to 0.00075 0.00081 2 0~000038 0.0O06 1 Between 0.00075 and 0.0005 rn idw a y 0 9000625 0.000015 0.0005 0 0005 0 0.0004 Between 0-0005 and 0.00025 nearer to 0.0005 0 -00043 7 0.000037 Between 0-0005 and 0.00025 nearer to 0.00025 O.0003 12 0*0O0012 0*00022 0.00025 0.00003 0.0001 6 Between 0.00025 and 0.0001 nearer to 0.0001 0*000138 0.00002 2 0.0001 0-0001 0 0al00G Between 0.000075 and 0.00005 0.0000625 0*0000025 Small quantities of inorganic salts, such a8 are found, for instance, in natural waters, have no influence upon the results. H. H. B. S. Titration of Phosphoric Acid with Uranium. N. Orlow. (Farmax. J., 1898, xx., 283 ; through Chem.Zeit. Rep., 1898, 233.)-As the standardization ofTHE ANALYST. 335 uranium solutions on pure sodium phosphate is troublesome, the author recommends the use of the double acetate of uranium and sodium-Na( CaH30,).2UOa(C,H,0,)2 -which forms anhydrous crystals, and can easily be obtained pure. F. H. L. APPARATUS. (Jour. Aww. Chem. S'oc., 1898, xx., 678-681.)-With the object of producing a more suitable lubricant for glass stopcocks, the author has made a series of experiments with various substances. A mixture which gave very satisfactory results was : Pure unvulcanized rubber, 70 parts ; speriiiaceti, 25 parts ; and vaseline, 5 parts. The materials were thoroughly mixed while hot, the rubber being melted first and the others stirred in. Another prepara- tion, which gave still better results, was made by mixing 70 parts of pure rubber with 30 parts of yellow unbleached beeswax. Old rubber does not answer well, as the mixture may become more or less granular and opaque. I t is stated that this lubricant prevents glass taps from sticking, even when concentrated solutions of Lubricants for Glass Stopcocks. F. C. Phillips. alkali are used, and is quite translucent in thin layers. c. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300332

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 335 R E V I E W . COMME:HCIAL ORGANIC ANALYSIS. By ALFRED H. BLr,m. Second edition. Vol. IV. London : J. and A. Churchill. Price 18s. With Vol. iv. the second edition of Mr. Allen's treatise, the production of which has extended over a period of fourteen years, is brought to its long-hoped-for con- clusion. We need say nothing as to the merits of the earlier portions of the work, since these have already been criticiscd in these pages and have stood the test of time and use, The concluding volume is worthy of its predecessors-finis coroiznt opus-and analysts are now placed in full possession of the greatest treatise on organic analysis which has ever appeared in England, or, indeed, in any country- a treatise which has become as indispensable in the laboratory as the classical work of Fresenixis.Mr. Allen is to be congratulated on the conipletion of the work to which, as he himself tells us, he has devoted the best years of his life. The volume under review commences with an account of the classification and the general properties and reactions of proteids or albuminous principles ; a detailed description is then given of the proteids of the egg, blood-plasma, urine, and plants. The last section treats more especially of the composition of wheat, barley, and malt. We note that the author restricts the terms " proteid " and " albuminous " to the substances of which albumin is the type, whilst gelatin and kindred substances are classed under the head of proteo'ids or albumino'ids. The word '' albumen " is also limited to its original signification--namely, white of egg- the term '' albumin " being applied to the most characteristic constituent of this and similar substances. These are welcome endeavours to secure uniformity in a nomenclature which is at present somewhat confused.The succeeding 178 pages are devoted to the consideration of milk and milk- products; and this is, perhaps, that portion of the volume which will appeal moreTHE ANALYST. especially to the public analyst. The average composition of milk, the methods for its analysis, the detection of adulteration, the question of standards and limits, the use of preservatives, etc., are discussed with ample detail, and the results of the most recent experiments are recorded. Cheese, cream, condensed milk, and other prepara- tions of milk, are then dealt with in an equally comprehensive and satisfactory manner; butter has already been considered in vol.ii. We are glad to find that, through the courtesy of Dr. T. E. Thorpe, Mr. Allen has been enabled to include a description, taken verbatim from an as yet unpublished report to the Local Govern- ment Board, of the method now adopted in the Government laboratory for the analysis of altcred milk. With the general principles of the method analysts are already acquainted, and it is now to be hoped that its value will be tested experi- mentally by independent observers. The analyses recorded in the report of samples of milk which have been kept for various periods-in some cases more than a year- certainly speak well for the process, which has, moreover, a scientific basis.Meat and meat-products are next considered, and the composition and analysis of ]neat-extracts receives full attention. A bibliography of this latter subject, which has been so much in evidence of late years, adds to the value of this portion of the work. Much of the following section, which deals with the proteids of digestion, has little to do with “commercial ” analysis; but the author has judged it well-and rightly, as we think-to record all facts which he has found to be of practical or analytical interest. The most recent views of modern authorities on this difficult subject are here to be found, and an account of the ingenious speculations of Latham and others as to the constitution of albumin affords a relief to the more practical parts of the volume.A chapter on haemoglobin and allied substances concludes the discussion of the true proteids, and an excellent account of the chemico-legal examination of blood- stains is here given. We may remark that the author diflers froin most British authorities on this subject in attaching considerable value to the measurement of the avcwtge size of the blood corpuscles in the differentiation of the blood of man and other animals, even in the case of old and dried stains. The remaining portion of the work treats of the proteoids or albuminofds, which are classed under the four heads of Collagenes or Gelato’ids, Fibroids, Chitinoids, and Keratofds. Among other matters of practical or commercial importance here dealt with may be mentioned the analysis of gelatin, the valuation of glue, and the examination of silk, wool, hair, and other fibres. A long list of addenda comprises notes on original publications which appeared too late to admit of being incorporated in the work. The recent alleged synthesis of albumin or peptone finds a place here, and it is pertinently pointed out that a process not involving the use of sulphur in any form cannot possibly result in the formation of a true proteid. Those analysts who have been unable to procure the earlier volumes of Mr. Allen’s treatise, which have long been out of print, will be glad to learn that they are being revised by Dr. Henry Leffmann, of Philadelphia. Vol. i. has already been issued, and Vol. ii. will follow shortly. T. S. t% N. L.

ISSN:0003-2654    

DOI:10.1039/AN8982300335

出版商:RSC    

年代:1898

数据来源: RSC