摘要:

NOVEMBER, 1912 Vol. XXXVII., No. 440. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE ordinary meeting of the Society was held on Wednesday evening, November 6, in the Chemical Society’s Room, 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 Meusrs.Thomas Rigby Greenough, B.A. (Cantab.), A.I.C., “ Beechwood,” Leigh, Lancs, Assistant Analyst in the City Laboratory, Liverpool ; Harold Lowe, M.Sc. (Manchester), A.I.C., 18, Hough Green, Chester, Assistant to Mr. W. F. Lowe, A.R.S.M., F.I.C. ; James P. Ogilvie, ‘‘ Homedale,” Hendon Lane, London, N., analytical and consulting chemist ; Stanley Elliott, A.I.C., ‘‘ Penshurst,” Windmill Lane, Enfield, assistant to Mr.C. H. Cribb, B.Sc., F.I.C. ; and John Algernon Lacy Sutcliffe, A.I.C., City Analyst’s Laboratory, Broad Street, Birmingham, assistant to Mr. J. F. Liverseege, F.I.C., were read for the first time. Messrs. S. W. Collins, B.Sc., F.I.C., and C. B. Lessner, were elected members of the Society. The following papers were read: ‘‘ Note on an Apparatus for Testing Water by Measurement of its Electrical Conductivity,” by L. Archbutt, F.I.C. ; ‘‘ The Detection and Estimation of Arachis Oil,” by Norman Evers, B.Sc. ; ‘‘ The Examina- tion of Chinese and Japanese Wood Oil,” by A. Chaston Chapman, F.I.C.; and (‘ The Estimation of Manganese by the Bismuthate Method,’’ by H. F. V. Little, A.R.C.S., B.Sc.

ISSN:0003-2654    

DOI:10.1039/AN9123700485

出版商:RSC    

年代:1912

数据来源: RSC

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486 SHREWSBURY : POISONOUS GASES FROM OILFIELDS POISONOUS GASES FROM OILFIELDS. BY HERBERT S. SHREWSBURY, F.I.C. RECENTLY a negro was killed by breathing the gas at the bottom of a pit under an oil derrick close to the Pitch Lake at La Brea, Trinidad. The pit was some 10 feet deep and surrounded the casing of the tubular oil-well, from which the gas most probably overflowed into the pit. Whilst working in this pit the man became giddy and had to be helped out.A sample of gas taken from the top of the well, or oil-tube, was forwarded to this laboratory, and the author found its composition to be as follows : Twelve hours afterwards he died. Sulphuretted hydrogen ... ... Saturated hydrocarbons ... ... Unsaturated hydrocarbons ... ... Oxygen ... ... ... ... Hydrogen ... ...... ... Nitrogen ... ... ... ... Carbon monoxide ... ... ... Carbon dioxide ... ... ..* ... ... 0.1 ... ... 1.1 ... ... 4.4 ... ... 2.5 ... ... 8.7 ... . . I 11.9 ... ... 18.8 ... ... 52.5 100.0 -- -- Assuming all the oxygen and some of the nitrogen to be derived from air, the amount of air present was found to be 43.4 per cent., and the composition of the gas as it issued from the ground was calculated as : Sulphuretted hydrogen ...... ... ... 0.2 Carbon monoxide ... ... ... ... ... 1.9 Unsaturated hydrocarbons ... ... ... ... 4.4 Saturated hydrocarbons ... ... ... ... 7.8 Carbon dioxide ... ... ... ... ... 20.9 Hydrogen ... ... ... ... ... ... 31.4 Nitrogen ... ... ... ... C . . ... 33.4 100.0 A. Wynter Blythe states that 0.05 per cent. of sulphuretted hydrogen in air is the utmost that can be breathed with safety, that 0.08 per cent.is dangerous, and 0.10 to 0.15 fatal to human life. According to Haldane, more than 0.15 per cent. of carbon monoxide is dangerous to human life, and 0.4 per cent. would kill in a, moderately short time. It will be seen that the gas, as it issues from the ground, is extremely poisonous, and that even when mixed with 43 per cent.of air it would kill when breathed for a short time-as, indeed, it did. The author has visited the Pitch Lake, and the following observations may be of interest. The surface of the lake is covered with little pools and channels of water, through which gas is constantly bubbling Gas also issues from the pitch itself, which is generally as firm as asphalt, but in places is soft, and in fact liquid.The gas has exactly the same odour as the sample described, the small percentageEVERS : THE DETECTION AND ESTIMATION OF ARACRIS OIL 487 of sulphuretted hydrogen mixed with the hydrocarbons producing a sweet and tar- like smell. It is an interesting fact, which the author has personally witnessed, that small fishes live in the pools through which the gas bubbles, notwithstanding its poisonous character. In view of the probability of this evolution of poisonous gas from oilfields being a phenomenon of common occurrence, a widespread publication of the above facts might be the means of averting loss of life. GOVERNMENT LABORATORY, TRINIDAD, B.W. I.

ISSN:0003-2654    

DOI:10.1039/AN9123700486

出版商:RSC    

年代:1912

数据来源: RSC

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EVERS : THE DETECTION AND ESTIMATION OF ARACRIS OIL 487 THE DETECTION AND ESTIMATION OF ARACHIS OIL. * BY NORMAN EVERS, B.Sc., A.I.C. (Read at the Meeting, November 6, 1912.) PART DETECTION. J. BELLIER (Ann. Chim. anal., 1899, 4, 4) suggested the following qualitative test for arachis oil in olive oil : One C.C. of the oil is saponified with 5 C.C. of alcoholic potash (85 grms. potash dissolved in a litre of 70 per cent.alcohol), 1-5 C.C. of acetic acid of such a strength as to exactly neutralise the alcoholic potash is added, and the tube cooled in water below 20" C. for not less than thirty minutes. The liquid is then diluted with 50 C.C. of 70 per cent. (by volume) alcohol containing 1 per cent. (by volume) of hydrochloric acid, and placed in water at 17' to 19O C. for an hour.When the oil contains more than 10 per cent. of arachis oil a precipitate is formed, while pure olive oils give a, clear solution. I have used this test on many olive oils and mixtures of olive oil with arachis oil, and have found it to give quite satisfactory indications with as little as 5 per cent, of arachis oil. As noted by Archbutt (J. Xoc. Chem. Ind., 1911, 30, 5-6; ANALYST, 1911, 36, 116), certain ngutralised residuum olive oils, known as L L saponified " oils, which contain a high percentage of unsaponifiable matter, give a, precipitate with this test.The test was modified by Mansfeld (Zeitsch. Untersuch. Nahr. a. Genussm., 1905, 17, 57), Adler (ibid., 1912, 24, 676), and Franz (Beitrage x. Nachweis und z. Kenntnisa cl. Erdnussoles Diss.Munchen, 1910). A more strongly alcoholic potash solution (80 grms. potash dissolved in 80 C.C. of water and diluted to a litre with 90 per cent. alcohol) is used, and the oil saponified in a flask with a condensing-tube for four minutes. This obviates a difficulty which I have frequently found with Bellier's test-viz., the loss of all the alcohol before the saponification is complete.After adding 1.5 C.C. of dilute acetic acid (1 volume glacial acetic acid to 2 volumea water) and 50 C.C. of 70 per cent. alcohol, the liquid is cooled to 15.5" C., and allowed to remain at this temperature for five minutes. In this way the long standing in cold water is dispensed with. I have found this test, for these reasons, to be * This work was carried out under the Analytical Investigation Scheme.488 EVERS: THE DETECTION AND ESTIMATION OF ARACHIS OIL preferred to that of Bellier.A distinct turbidity is produced by 5 per cent. of arachis oil, and, except in the case of a sample of ‘‘ saponified ” oil, I have never found a pure olive oil which gave a positive result. PART II.-ESTIMATION. Franz and Adler (Zoc. cit.) have shown that the above qualitative test can be made approximately quantitative by determining the temperature at which a turbidity is first produced.The following table is taken from their paper, and shows the various temperatures of crystallisation ” of olive and arachis oils and of mixtures : Oil Temperature of Crys tallisa tion. Oil. Temperature of Crystallisation. Olive oil ... ... ...Arachis oil, 5 per cent. 9’ 10 7 , ¶ > 20 ?, ,, 30 ?, 7 9 40 9, O c . 11 -8-14 -3 15 *9-17 -0 19-8 25-7 29-2 31-5 Arachis oil, 50 per cent. $ 9 60 1 , 9 , 70 9 , 9 , 80 9 , 7 , 90 $ 9 Arachis oils ... ... O c. 33.8 35.3 36.6 38.0 39.3 40*0-40*8 I have been able to verify these temperatures given by Adler with several olive and arachia oils and mixtures, and have found the values obtained remarkably constant, and in all cases within the limits given by him.I n the case of the “saponified” olive oil mentioned above, a faint turbidity was observed as high as 45” C . , becoming more definite as the liquid was cooled ; but no distinct precipitate could be seen until after standing at 15.5” C. for five minutes. This is quite unlike the behaviour of arachis oil, which gives a definite precipitate very shortly after the first opalescence is observed.BeZZier’s P!rocess.-This process is carried out as follows : Five grms. of the oil are weighed out, saponified with 25 C.C. of alcoholic potash (85 grms. potash dissolved in a litre of 70 per cent. alcohol), and the fatty acids liberated with 7-5 C.C. of dilute acetic acid, which exactly neutralises the potash.The liquid is then cooled rapidly and allowed to stand for an hour to precipitate the fatty acids. After filtering, the fatty acids are washed at 15’ to 20’ C. with 70 per cent. alcohol containing 1 per cent. (by volume) of HCl until the filtrate gives no turbidity with water. The precipitate is then dissolved in 25 to 50 C.C. of boiling alcohol of 92 to 93 per cent.strength, and sufficient water added to reduce the strength to 70 per cent. The fatty acids are allowed to crystallise below 20” C. for an hour, then filtered off, washed with 70 per cent. alcohol until no turbidity is given with water, dissolved in warm ether, and weighed. Using this method, Bellier obtained 4.2 per cent. of fatty acids from two arachis oils, and none or practically none from several olive oils.Archbutt (Allen’s “ Commercial Organic Analysis,” 4th edition, vol. ii., p. 101) states that he has obtained low results by this method.EVERS: THE DETECTION AND ESTIMATION OF ARACHIS OIL 489 Renard. The process was tested on various oils in conjunction with Renard's process as modified by Archbutt (ibid., p. 93). The resalts are given in the following table : Bellier .TABLE I. Meltingpoint. Oil. Solubility, Grms. per 100 C.C. Arachis (A) . . . ... Arachis (B) ... ... Olive oil, Malaga ... Olive oil, Nice superfine . . . Olive oil, '( Seconds " . . . Olive oil, 50 per cent. Arrtchis (A), 50 per cent. } At 13" C. 0-016 0.012 0.009 ~ Arachidic Acid. per Cent. Me1 ting- point. O c. Arachis Oil. per Cent. Arachidic Acid.per Cent. Me1 ting- point. (1. A rachis Oil. per Cent. 4.59 5.15 0 0 0 2.28 73 *5 72.0 - - - 73.5 3.56 3-76 0 Trace Trace 1.36 71 71 - - - 72 78 83 - - - 30 The factor used in the calculation of the percentage of arachis oil by Bellier's process is 22, as used by Bellier. It is obvious that the results obtained are exceed- ingly low. This may be due either to the solubility of arachidic and lignoceric acids in 70 per cent.alcohol, or to the incomplete precipitation of the fatty acids on account of their solubility in the strong solution of oleic and other fatty acids. Solubility of Arachidic and Lignoceric Acids in 70 per Cent. Alcohol.-Benard (Compt. rend., 73, 1330) states that these acids are quite insoluble in 70 per cent. alcohol, but the following determinations show that they possess a quite marked solubility : The acids employed were obtained from arachis oil by Renard's process.The solubility was determined by dissolving about 0.2 grro. of fatty acid in 100 C.C. of 93 per cent. alcohol, adding suEcient water to reduce the strength to 70 per cent., and keeping at a fixed temperature for several hours. The liquid was then filtered at the same temperature, a, measured volume of the filtrate evaporated to dryness, and the residue weighed.The following are mean values of several results obtained : TABLE 11. 71' C. 72" C. 7 3 O c. At 18" C. 0.023 0.017 0.012490 EVERS: TRE DETECTION AND ESTIMATION OF ARACHIS OIL The solubility was also determined when the fatty acids were washed on a filter-paper, about 0-2 grm.being used. The results obtained were- Melting-poin t, Gyms. dissolved O c . per 100 C.C. 71 0.008 72 0.006 73 0*005 The presence of 1 per cent. of hydrochloric acid in the alcohol does not affect the solubility. Saponification, etc.-It is preferable to use the alcoholic potash recommended by Adler, as in the qualitative test, and to saponify in a flask under a reflux condenser.As a slight excess of acetic acid does not affect the precipitation, 7-5 C.C. of a solution of 1 volume glacial acetic acid in 2 volumes water are added instead of exactly adjusting the strength to that of the potash. Bellier states that in the absence of 1 per cent. of hydrochloric acid from the 70 per cent, alcohol, the washing is very tedious. The reason does not seem obvious, but this is undoubtedly the case, though the solubility of the arachidic and lignoceric acids themselves is not affected by this amount of hydrochloric acid.Crystallisation from 90 per Cent. Alcohol.-The final cry stallisation was carried out from 90 per cent. instead of 70 per cent. alcohol, where the quantity was sufficient, and the crystals washed, first with 90 per cent., and then with 70 per cent.alcohol as in Renard'sprocess. This procedure gives a purer acid of higher melting- point. Correction for Solubility in 70 per Cent. Alcohol.-The process was carried out with the above modifications, and corrections added separately for the volume of 70 per cent. alcohol, used for crystallisation and washing, from Table 11. above.It was found, however, that when the proportion of arachis oil was less than 50 per cent. the results obtained were too high, because the correction varied with the amount of the precipitate. In order to avoid complication the list of corrections given in Table 111. has been drawn up, by means of which a single correction is added for the total volume of 70 per cent. alcohol used, and will be found sufficiently accurate for ordinary purposes.TABLE 111. Weight of Acids. (Correct,ed for 90 per Cent. Alcohol.) Above 0.10 grm. ... ... ... 0-08-0.10 ,, ... ... ... 0*05-0*08 ,, ... I.. . .. 0.02-0-05 ,, ... ... ... Less than 0.02 grm. ... ... Factor for conversion of percent- age of fatty acids to arachis oil Correction per 100 c.c., 70 per Cent. Alcohol. Me1 ting-point, 71" C.0.013 grm. 0.011 ,, 0.009 ,, 0.007 ,, 0.006 ,, 17 Melting-point , 72" c. 0.008 grm. 0.007 ,, 0.007 ,, 0.006 ,, 0.005 ,, 20 Me1 ting-point, 73" c . 0.006 grm. 0.006 ,, 0.005 ,, 0.005 ,, 0.004 ,, 22EVERS : THE DETECTION AND ESTIMATION OF ARACHIS OIL 491 Oil. Arachis (A) ... ... ... { Arachis (B) ... ... ... { Arachis (0) ... ... ... Arachis (D) ... ... ... Arachis (A), 50 per cent.. . . Olive " Nice," 50 per cent. ... Olive "Nice," 65 per cent. ... Arachis (A), 35 per cent. Arachis (A), 20 per cent. ... Olive ' ' Nice, ' ' 80 per cent . . . . Arachis (C), 20 per cent. ... Olive '' Malaga," 80 per cent. Arachis (A), 10 per cent. ... Olive '' Nice," 90 per cent. ... Arechis (B), 10 per cent. ... Olive "Nice," 90 per cent. ... Arachis (C), 10 per cent.... Olive Malaga," 90 per cent. Arachis (A), 5 per cent. Olive '6 Nice," 95 per cent. ::: } Sesame .. ... ...{ -.* 1 Cotton-seed . . . . . . . . . { . . . { Olive 1 6 saponified 9' . . . 90 70 90 70 90 90 90 70 90 90 70 90 70 90 70 90 70 90 70 90 70 70 90 70 90 $0 90 70 TABLE IV. Grm. 0.160 0.218 0.163 0.233 0.152 0.194 0.056 0'090 0.045 0.029 0-059 0 *024 0.030 0'012 0-021 0.009f 0.008 0 0'012 0 0.011 0.007 0 0.012 0 0.006 0.014 0.021 Gm.0.040 0.045 0.054 0.033 0-032 - - - 0'020 0'040 - 0'012 - 0.020 - 0.008 - - - - - - - - - - - - Grm. 0.027 0.065 0.032 0.068 0.034 0.028 0.022 0.055 0.029 0 -020 0'040 0.019 0.024 0'015 0.027 0.008 0.015" - 0.018 - 0-016 0-012* - - - - - - Grm. 0.227 0.283 0'240 0'301 0.240 0'255 0'110 0-145 0'094 0.089 0.099 0.055 0.054 0'047 0-048 0.025 0 *023 0.030 0.027 0.019 - -- - - - - - 4.54 5.66 4-80 6.02 4.80 5-10 2 '20 2.90 1.88 1-78 1 *98 1 '10 1 *08 0.94 0-96 0 -50 0'46 0 0-60 0 0.54 0.38 0 0.24 0 0 -12 0.28 0'42 73 71 72 71 72 72 73 71 71 72.5 71 71 71 72 71 73 70 71 71 - - - 64 - 50-55 64-67 64-68 100 96 96 102 96 102 48 49 32 37 34 19 18 19 16 11 8 - 10 - 9 6 '5 - - - - - * In these cases the correction has been added for melting-point 71" C.-f This result was obtained by recryshllising the fatty acids obtained from 70 per cent. alcohol from 10 C.C. of 90 per cent. alcohol. The Modi$ed Process.-Weigh out 5 grms. of the oil into a saponification-flask, add 25 C.C. of alcoholic potash (80 grms. potash dissolved in 80 C.C. water and diluted 00 a, litre with 90 per cent.alcohol), and saponify for about five minutes under a reflux condenser. To the hot soap solution add 7.5 C.C. of acetic acid (1 volume of glacial metic acid to 2 volumes of water) and 100 C.C. of 70 per cent. alcohol containing492 EVERS: THE DETECTION AND ESTIMATION OF ARACH~S OIL 1 per cent. (by volume) of HCI, and cool to 1 2 O to 14" C. for an hour. Filter and wash with 70 per cent.alcohol containing 1 per cent. HCl at 17' to 19" C., the precipitate being broken up occasionally by means of a platinum wire bent into a loop. The washing is continued until the filtrate gives no turbidity with water, the washings being measured, Dissolve the precipitate, according to its bulk, in 25 to 70 C.C. of hot 90 per cent. alcohol, and cool to a fixed temperature between 15" and 20" C.If crystals appear in any quantity, allow to stand at this temperature for one to three hours, filter, wash with a measured volume of 90 per cent. alcohol (about half the volume used for crystallisation), and finally with 50 C.C. of 70 per cent. alcohol. Wash the crystals with warm ether into a weighed flask, distil off the ether, dry at 100" C., and weigh.If the melting-point is lower than 71" C., recrystallise from 90 per cent. alcohol. Add the correction for the solubility in 90 per cent. alcohol as in Renard's process, from the table given by Archbutt (Allen's "Commercial Organic Analysis," 4th edition, vol. ii., p. 94), and also for the total volume of 70 per cent. Jcohol used in precipitating and washing (including the 100 C.C. added in the first instance) from Table 111. If there are no crystals from 90 per cent. alcohol, or if they are only in very small amount, add a sufficient quantity of water to reduce the strength of the alcohol to 70 per cent. (31 C.C. water to 100 C.C. 90 per cent. alcohol). Crystallise a t 17" to 19" C. for an hour, filter, wash with 70 per cent. alcohol, and weigh as before, adding the correction for the 70 per cent. alcohol from Table 111. If the melting- point is below 71' C., recrystallise from a small quantity of 90 per cent. alcohol, or again from 70 per cent, alcohol. The results obtained by this method are given in Table IV. The following oils gave no crystals : Olive oils, including L L Nice superfine," ': Nice In conclusion, I wish to express my thanks to Mr. L. Archbutt for his valuable seconds,'' 4 L Malaga:" and eight of unknown origin, almond, poppy, and rape oils. advice and assistance throughout the work.

ISSN:0003-2654    

DOI:10.1039/AN9123700487

出版商:RSC    

年代:1912

数据来源: RSC

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492 EVERS: THE DETECTION AND ESTIMATION OF ARACH~S OIL ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Insoluble Carbohydrates of the Apple. E. C. Schneider. (Amer. J. Physiol., 1912, 30, 258 ; through Chem. Zentralbl., 1912, II., 937.)-Marc obtained from pounded Ben Davis apples by extraction with water, alcohol, and ether con- tained 28 per cent. of reducing sugar, 28 per cent.of pentosan, and 11.5 per cent. of galactan ; the pectin prepared from this marc by hydrolysis with 0-4 per cent. hydrochloric acid at a, temperature of 38OC. contained 57-5 per cent. reducing sugar, 36 per cent. pentosan, and 46 per cent. galactan. Intestinal bacteria, destroyed the hemicellulose and pectin ; reducing sugars were not found as end-products of thisFOOD AND DRUGS ANALYSIS 493 action.Marc and pectin were not hydrolysed by animal enzymes, malt diastase, or taka diastase. Experiments on human beings showed that 79 to 84.5 per cent. of the hemicelluloses of the marc were utilised or destroyed during digestion. 0. E. M. Pentosan and galactan were about equally attacked. Detection of Cane Sugar. S. Rothenfusser. (Chem. Zeit., 1912, 36, 1100- 1101.)-With the exception of cane sugar and raffinose, all sugars are completely destroyed when treated with hydrogen peroxide in alkaline solution (Cf.ANALYST, 1910, 35, 539 ; 1911, 36, 588), and the presence of cane sugar in the resulting solution may be ascertained by means of the diphenylamine reagent described previously by the author (ANALYST, 1910, 35, 208).The use of calcium or barium hydroxide is preferable to that of an alkali hydroxide, as in the former case a precipitate of barium peroxide is formed on the addition of the hydrogen peroxide, and oxygen is liberated quite slowly, so that the sucrose present is not attacked during the digestion. At the end of the operation the excess of hydrogen peroxide in solution is destroyed by the addition of a catalyst, and the solution is tested with the diplienylamine reagent.w. P. s. Estimation of Cane Sugar in Foods, ete. A. Jolles. (Chem. Zeit., 1912, 36, 1100.)-In the method described originally by the author (ANALYST, 1911, 36, 28) it was recommended that not more than 2 per cent. of sugars other than cane sugar should be present in the solution in which the latter sugar is to be estimated, as with larger quantities the solution becomes brown in colour and the polarimetric examina- tion is affected.He now states that the brown coloration which develops when concentrated sugar solutions are employed in the process may be removed by means of mercuric acetate and phosphotungstic acid. After the sugar solution has been heated with sodium hydroxide solution for twenty-four hours at 37"C., a measured portion of it is neutralised with dilute acetic acid, and 50 per cent.mercuric acetate solution is added as long as a precipitate is formed, the quantity added being noted. The mixture is then filtered, and an aliquot portion of the filtrate is precipitated with a 25 per cent. phosphotungstic acid solution, the necessary volume of which is also noted.The mixture is again filtered, and then examined with the polarimeter. The rotation observed is due solely to cane sugar, and in calculating the quantity of the sugar present, allowance is made for the dilution caused by the introduction of the precipitants. w. P. s. Analysis of Commercial Casein. W. Hopfner and H. Burmeister. { Chem. Zeit., 1912, 36, 1053-1054.)-Good commercial casein should exhibit at the most a slight yellow colour, and should be free from rancid or cheese-like odour and from foreign matters.For the estimation of the moisture, 5 grms. of the sample are dried at a temperature of 100" to 105" C. until constant in weight ; this requires about two hours' heating, and the weighing should be made at frequent intervals to avoid oxidation of the casein by prolonged heating.The quantity of fat is best estimated by extraction in a Soxhlet apparatus by a mixture of ether and petroleum spirit, the casein being ground and mixed with sand before being placed in the cartridge. A494 ABSTRACTS OF CHEMICAL PAPERS silica basin should be used for the estimation of the ash, and in cases where the ignition proceeds with difficulty the carbonised mass must be extracted with water in the usual way.The acidity of the sample is estimated under the following conditions : Ten grms. of the casein are shaken with 100 C.C. of water, filtered, and 50 C.C. of the filtrate titrated with FG potassium hydroxide solution, using phenolphthaleyn as indicator. For this purpose 10 grms.of the sample are mixed with 50 C.C. of water and 2 C.C. of 33 per cent. ammonia. After the lapse of a few hours the mixture is warmed to 60’ C. Pure casein swells and yields a thick, opalescent liquid, whilst casein which has been stored for a long time gives a turbid liquid. If sand is present it settles to the bottom of the liquid and may be separated and weighed; foreign substances, such as starch, etc., may be detected by means of the microscope.The total nitrogen is estimated by the Kjeldahl method; as regards the calculation of nitrogen into casein, attention is drawn to the different factors, varying from 6.34 to 6.99, which have been proposed. The author finds that the factor 6-61 probably is most correct, as the quantity of casein calculated by its use generally approximates 100 per cent.The maximum and minimum results obtained on the analysis of thirteen samples of commercial casein were : Water, 7.27, 10.50 ; fat, 0-28, 2.06 ; ash, 3-53, 4-95; nitrogen, 12.52, 13.55; nitrogen in the fat and asb-free, dry substance, 14.68, It is useful to determine the solubility of the casein in ammonia. 15.65 per cent. w. P. s.Edible Beans from Hong-Kong. (BwZZ. Imp. Inst., 1912, 10, 235-239.)- The following are analyses of three varieties of beans from Hong-Kong, the figures yielded by the corresponding varieties of Indian origin being given in each case : Moisture ... ... Total nitrogen as crude proteins . . . True proteins . . . 0 t her nitrogenous substances ... Fat ... ... ... Starch, etc. ... ...Fibre ... ... Ash ... ... ... (( Nutrient ratio ” . . . ‘‘ Food units ” ... Hong- Kong. Dolichos Lablab, Linn. Per Cent. 12.63 19.51 18.46 1.05 1.24 57-66 5.89 3.07 1 : 3.10 109.5 Indian Lablab Beans. Per Cent. 12.1 to 14.6 17.1 to 224 - - 1.4 to 2.3 54.2 to57.4 5.0 to 6.5 3.4 to 3.6 1 : 2.5 to 1 : 3.7 105.9 to 113.7 H0ng Kong. Yips Catiang, Walp. Per Cent. 11 -65 22.05 20.38 1-67 1.23 57.99 3.83 3.25 1 : 2.75 116.2 Indian Catiang Beans.Per Cent. 12.7 23.1 - - 1.1 55.3 4-2 3.6 1 : 2.5 115.8 Hong - Kong. Phaseolus Mungo, Linn. Per Cent. 11.88 19-98 18.04 1.94 0.75 68.96 4.76 3 *67 1 : 3.03 110-8 Indian ,, ( ( Mung Beans. Per Cent. 10-1 to 11.4 22.2 to23.8 - - 2.0 to 2.7 54.1 to 55.8 4.2 to 5.8 3.8 to 4.4 1 : 2 5 to 1 : 2.7 116.3 to 119.3FOOD AND DRUGS ANALYSIS 495 The ‘‘ nutrient ratio” is the ratio between the percentage of crude proteins and the sum of the percentages of starch and fat, the latter being first converted into its starch equivalent. The ‘‘ food-units ” is the total obtained by adding the percentage of starch to 2.5 times the sum of the percentages of fat and crude proteins.A. R. T. Estimation of Fat in Cocoa by Means of Zeiss’ Refractometer.0. Richter. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 24, 312-319.)-The cocoa powder is treated with trisodium phosphate solution and a mixture of ether and alcohol, and the amount of fat present is determined from the refraction of the ethereal solution. The trisodium phosphate solution should contain 65 grms. of the salt per litrs, and the alcohol-ether mixture is prepared by mixing equal volumes of these solvents.Preliminary experiments must be made to ascertain how much of the ether-alcohol must be added to 100 C.C. of the phosphate solution so that 5 C.C. of ether shall separate after mixing. The proportions of ether and alcohol in the mixture are so adjusted that about 25 C.C. of the mixture must be added to yield 5 C.C.of ethereal layer. Ten grms. of the cocoa powder are then mixed with this quantity of the ether-alcohol mixture, and 100 C.C. of the phosphate solution are added. The whole is then shaken for some ten minutes and allowed to settle; in the case of chocolate or coarsely powdered cocoa the mixture may be warmed slightly, and then cooled to 17.5’ C., at which temperature all measurements of the solutions are made.The clear ethereal layer is next examined in the refractometer, and the percentage quantity of fat ( F ) present is calculated from the formula : where n is the refractive index of cocoa butter (1*4653), nl that, of the solvent (1*3543), n.2 that of the fat solution observed, x the excess volume of the ether (5 c.c.), y the sp. gr. of the fat, and z the weight of substance in grms.(10 grms.). Tables are also given showing the quantity of fat aorresponding with refractive indices ranging from 1.3560 to 1.4200. w. P. s. Studies on Flour. R. Fanto. (Zeitsch. Untersuch. Nahr. Genussrn., 1912, 24, 269-274.)-With regard to the relation between the gluten-content of a flour and its baking quality, the author points out that rye-flour (which does not yield a coherent.eake of gluten although it possesses good baking qualities) does not contain any substances which prevent the coagulation of its gluten or of that of wheat-flour. A mixture of rye- and wheat-flours yields the proportionate quantity of gluten. Rye- flour, therefore, does not appear to contain gluten. The grain obtained by crossing wheat and rye gives a satisfactory cake of gluten.The maximum solubility of the proteins of both wheat- and rye-flours in alcohol is reached when the alcohol has a strength of from 50 to 60 per cent. by volume. w. P. s. Composition of the Fatty Oils obtained from the Seeds of Illicium Verum Hook and Illicium Religiosum Sieb. J. Bulir. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 24, 309*312.)-The fruit of lllicium verum Hook (Chinese496 ABSTRACTS OF CHEMICAL PAPERS star-anise) is frequently adulterated with the poisonous fruit of Illicium religiosum Sieb.(Japanese star-anise); the fruits are very similar in appearance, but may be distinguished from one another by careful examination. The seeds of both fruits contain a fatty oil ; the oils were extracted by the author from specimens of the two seeds by means of ether, then freed from ethereal oils by steam, and dried in an atmosphere of coal-gas.Analyses of the oils yielded the following results : IZZiciurn Yerum. Oil. Fatty Acids. Sp. gr. at 15" C. ... ... Saponification value . . . Iodine value (Hiibl) . . . Hehner value ... ... Reichert-Meissl value . .. Mean molecular weight 0.9264 193.8 93.1 95.2 1.4 - - 200.2 97.4 - - 279-7 Oil.0,9295 193.4 90.6 95.0 1.5 - F a t t y Acids. - 200.7 93.6 - - 279.0 In the case of Illiciwm werurn the fatty acids consisted of-Oleic acid, 45.0; linolic acid, 23.9; palmitic acid, 23.2; stearic acid, 2.6 per cent. The fatty acid from the oil of Illicium religiosum consisted of-Oleic acid, 60.2 ; linolic acid, 9.8 ; w. P. s. palmitic acid, 22.5 ; stearic acid, 2.5 per cent.Shea-Nuts and Shea-Butter. (Bull. Imp. Inst., 1912, 10, 281-292.)-The shea-nut is the product of Butyrospermum Parkii, found in West Africa and Uganda, etc. The figures yielded on analysis by the "butter" prepared by the natives, and by the fat extracted from dried kernels by petroleum ether, are as follow : SHEA-BUTTER from- Lagos ...... ... Gold Coast, 1 ... ... 9 , 9 , 2 . ' * Bahr-el-Ghazal . . . ... FAT EXTRACTED from kernels Southern Nigeria, 1 ... 9 , ,, 2 ... 9 t ,, 3 ... ,, 4 ... Bahr-el-Ghazal . . . ... ... from- 9 9 Sp. Gr., 99" - c. 15" 0.862 - - - 0.869 0.867 - - 0.859 Saponi- fication Value. 179.0 184.6 183.0 181.7 181.5 182.8 181.2 180.2 184.0 Iodine Value. 'er Cent 58-0 56.0 56.7 54.0 62.0 57-17 59.4 55-8 62-9 isolublt Patty Acids.'er Cent, 96.5 - - - 91.2 94.6 - - 91.9 Jnsaponi fiable Matter. Per Cent, Titer 0. pt. Percent- age of Fat in Kernels. - - - - 48.6 52.4 41.4 46.2 47.2FOOD AND DRUGS ANALYSIS 497 Oil* Per Cent;. The presence of unsaponifiable matter is accounted for by the presence in the nuts of latex containing a gutta-like body. Any appreciable quantity of this unsaponifiable matter will render the fat less suitable for use in the manufacture of butter substitutes or of soap, The fat appears to contain oleic and stearic acids, and possibly arachidic or lauric acid.The composition of shea-nut oil-cake is shown below in comparison with other oil-seed cakes : Carbo- Crude llgdrates. Fibre. Per Cent. Per Cent. Per Cent. Moist w e .Per Cent 20.30 11.38 6.56 9.50 11.07 Shea-nut cake ... ... Cotton-seed cake (decorti- cated ... ... ... Cotton-seed cake (unde- corticated) . . . ... Linseed cake ... ... Soya-bean cake . . . ... 11.13 48.54 6-68 43.78 23.56 5-18 24.62 29 28 21.19 29-50 35.54 9.10 38-82 26.51 5.85 7.85 9.00 13.75 11.16 12.70 Ash. Per Cent. 5.50 7-10 4-60 5-20 5.05 Shea-nut cake possesses a, bitter and unpleasant taste, probably due to the presence of saponin, as is the case with other cakes from sapotaceous oil-seeds.The cake is low in proteins, and, although not actively poisonous, animals do not readily become accustonied to eating it, even in small quantities. A. R. T. Crude Phytosterol of Cocoanut Oil and the Crude Cholesterol of Butter Fat, and the Detection of Cocoanut Oil in Butter Fat.D. D. Kedro- vitsch. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 24, 334-335.)-Six different specimens of cocoanut oil yielded from 0.09 to 0.30 per cent. of crude phytosterol, and the melting-point of the phytosterol acetate varied from 122' to 125" C. Butter fat was found to contain about 0.30 per cent. of crude cholesterol, the acetate of which melted at 113' t o 113.5" C.From the examination of the phytosterol- cholesterol acetate obtained from mixtures of cocoanut oil and butter fat, it was found that the presence of 10 per cent. of the former could be detected, the melting- point of the acetate, in this case, lying between 114.8' and 117.5' C. w. P. s. Solanidine from Solanzmz Tziberosunz. A. Colombano. (Gaxz. Chim. Ital., 1912, 42, 101-116.)--The solanidine obtained in the hydrolysis of the solanine from the germ of the potato differs in chemical composition and physical properties from the solanidine derived from Solanum sodommm.Specimens of potato solanidine prepared by various methods melted at 214" to 215O C., and had the composition C,5E,,N0 when dried at 105" C. Commercial samples of solanidine and specimens prepared from commercial samples of solanine also had the ~ a m e composition and melting-point.The solanidine from S. sodomaurn crys tallised in nacreous scales, melting a t 197' to 198O C., and had the composition C1,H,lNO after drying at 105" C. Another difference between the two compounds is that solanidine from498 ABSTRACTS OF CHEMICAL PAPEKS 8. sodomaum does not decolorise an aqueous or chloroform solution of bromine, whereas the potato solanidine forms a fairly stable compound with bromine, melting (with decomposition) at 80" to 90" C.C. A. M. Polarimetric Estimation of Starch in Sausages. P. Lehmann and E. Schowalter. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 24, 319-327.)-The method proposed depends on the optical rotation of starch in hydrochloric acid solution.Lintner and Ewers have already given values for the rotation of starch in acid solution (cf. ANALYST, 1906, 31, 25; 1907, 32, 179), but the authors find that commercial wheat-starch has a specific rotation of + 181.1' and potato-starch + 183*15", under the conditions of their experiments. I n the process given below the quantity of substance taken for the estimation and the volumes of the solution are such that each degree of rotation exhibited by the final solution is equivalent to 1 per cent.of starch. The sausage is finely divided, and 27-5 grms. are mixed with 80 C.C. of alcoholic potassium hydroxide solution (100 C.C. of potassium hydroxide dissolved in 100 C.C. of water and diluted with 96 per cent. alcohol to 1 litre) and allowed to stand over-night. The mixture is then boiled under a reflux condenser, and the liquid portion is decanted; the residue is washed once with the alcoholic potassium hydroxide solution, and then with 55 per cent.alcohol, until the washings do not yield a turbidity with hydrochloric acid. Decantation usually suffices in this part of the process, and filtration is seldom necessary.The residue is then dissolved by heating it on the water-bath with 2 C.C. of water and 5 C.C. of 8 per cent. sodium hydroxide solution; the mixture is now neutralised with hydrochloric acid, 25 C.C. of; hydrochloric acid are added, and the whole is heated for ten minutes on the water-bath. The mixture is then cooled rapidly, neutralised by the addition of 12.5 C.C.of sodium hydroxide solution, and filtered, the filtrate being collected in a 100 C.C. flask. The precipitate obtained by mixing 3 C.C. of basic lead acetate solution with 6 C.C. of 10 per cent. ammonia is added, the whole is diluted to 100 c.c., filtered, and the filtrate is examined in a 220 mm. tube in the polarimeter. If a 200 mm. tube is employed, 25 grms. of the material should be taken for the estimation.w. P. s. Lintner's Polarimetric Method for the Determination of Starch. C. E. G. Porst and H. A. Crown. (Eighth Inter. Cong. App. Chem., 1912, vol. 13, 213-218.) -The authors have investigated the effect of varying the following conditions : (1)Temperature of digestion with concentrated hydrochloric acid ; (2) timeof digestion ; (3) time of standing after adding the phosphotungstic acid before the reading is taken ; (4) volume and concentration of phosphotungstic acid.Results are concordant when the same conditions are observed, and the following method is recommended : Five grms. of starch, or a weight of the finely ground substance equivalent to 5 grms. starch, are mixed with 20 C.C. of water in a, mortar cooled down in ice-water.To this is added 40 C.C. of concentrated hydrochloric acid, previously cooled down in a freezing mixture, and the solution is kept at 20" C. for half an hour. The contents of the mortar are transferred to a 200 C.C. flask, 10 C.C. of a 4 per cent. phosphotungstic acid solution added, and made up to volume at 20' C. with acid of 1.125 sp. gr.FOOD AND DRUGS ANALYSIS 499 The flask is then kept for half an hour in a water-bath at 20' C., filtered, and exactly fifteen minutes after filtering the reading is taken at 20' C.Dry maize starch was thus found to have an [aID 199.4. In applying the method to the determination of starch in maizo kernels a correction must be applied for the water-soluble matter present. Good agreement was obtained when using the acid method as compared with the diastase and Sachsse methods.In materials such as gluten meal rich in proteins it was found that the readings increased up to a point with the amount of phosphotungstic acid employed to precipitate the protein. The maximum reading was obtained with an amount equivalent to 50 C.C. of the 4 per cent. solution. If more than this were added, the reading fell owing to precipitation of starch.Even with this material, which contained nearly 50 per cent. of protein, the starch value obtained was 44-7 (using the maximum reading), as against 45.2 per cent. by the Sachsse method. The whole operation only takes one hour and a quarter, and if the temperature is kept at 20" C. no inconvenience arises from acid fumes.(Cf. ANALYST, 1909, 34, 332.) H. F. E. H. Examination of Storax. C. Ahrens. (Zeitsch. ufeentl. Chem., 1912, 18, 267-272 ; through Chem. Zentralbl., 1912, II., 873-874.)-A method of examination is based upon the fact that storax is partially soluble in petroleum spirit. From 4 to 5 grms. of the sample are mixed with about 5 grms. of sand and repeatedly triturated with cold petroleum spirit (sp.gr. 0-65 ; b.-pt., up to 70" C.), the successive extracts being decanted through a filter, until in all about 350 to 400 C.C. of the solution have been obtained. This is distilled in a tared flask and the residue dried in a hot oven until constant in weight. I t should be light yellow in colour, strongly refractive, very viscous, and have a pleasant aroma. Pronounced adulteration is indicated by the residue being darker in colour and more solid, and by its odour.This residue is now dissolved in about 30 C.C. of cold neutral alcohol (95 per cent. by vol.) and the solution titrated with alcoholic potassium hydroxide solution, with phenolphthalein 8s indicator, to obtain the acid value; after which an additional 25 C.C. of the alkali solution are added, the flask closed and allowed to stand for twenty-four hours, and the excess of alkali titrated to obtain the saponification value.The moisture is estimated by triturating 4 to 5 grms. of the storax with anhydrous sodium sulphate and ether, and filtering the liquid through a tared paper. The filtrate and washings are mede up to 100 c.c., then dried further by means of anhydrous sodium sulphate, and 50 C.C.thereof evaporated in a tared flask. The sodium sulphate is then washed out of the mass on the filter, ar.d the residue dried and weighed. The sum of the two residues deducted from the amount of substance taken gives the amount of water. From the examination of a large number of samples the following limits are provision- ally suggested for commercial storax : Petroleum spirit extract, 37.6 to 56.0 per cent. (mean 45.2) ; acid value of petroleum spirit extract, 33.1 to 62-9 (mean 46-7) ; and saponification value of petroleum spirit extract, 191.3 to 203-3 (mean 196.1).Products with values outside these limits are to be regarded as inferior or adult erst ed. C. A. 114.500 ABST.RACTS OF CHEMICAL PAPERS Tea-Seed Oil and Cake.(Bull. Imp. Inst., 1912, 10, 234-235.)-The seeds of of Camellia Sasa.nqua (tea-seed) are expressed by the Chinese for their oil, which is used as an illuminant, the residue being employed as a soap-substitute, by virtue of the saponin it contains. Samples from Hong-Kong gave the following results on analysis : TEA-SEED CAKE. Per Cent. Moisture ... ... ... 8-33 Crude proteins ...... ... 6.49 True proteins ... ... ... 6.13 Other nitrogenous substances 0-36 Fat ... ... ... ... 1.31 Starch, etc. ... ... ... 43.24 Fibre ... ... ... ... 37.43 Ash ... ... ... ... 3.20 TEA-SEED OIL. Sp. gr. at 15.5” C. ... ... 0.918 Acid value ... ... ... 9.4 Saponification value , . , ... 193.4 Iodine value per cent. ... ... 87.5 The oil sometimes contains saponin, and therefore is unsuitable for edible use.The cake contains 7 to 8 per cent. of saponin, and has an unpleasant and bitter taste, and cannot be used as a feeding-cake. The amount of saponin is less than is present in quillaia bark, but the cake may be suitable for use in the preparation of vermicides for dressing lawns. A. R. T. I t contains no alkaloids. Analyses of Ceylon Tobaecos.(Bull. Imp. Inst., 1912, 10, 187-205.)-The following are typical examples of analyses of Ceylon-grown tobaccos : Samples froiii Trincomalee. Samples from &hha-Iluppallama. “Sumatra No. 1.” ” Sumatra, No. 2.” (‘Java, No. 2.” “ Java, No. 3.” December Crop, 1909. 1909.10 Crop. Per Cent. 17.5 1-8 1-5 16.6 Per Cent. 15.1 1.7 3.1 12.6 Per Cent. 12.5 1.1 2.0 18.0 Per Cent. 13.2 1.8 2.7 15.3 Per Cent. 9.8 3.0 3.2 15.6 Yer Cent.15.1 1.4 3.3 12-5 Moisture ... ... Nicotine ... ... Nitrogen ,.. . a . Ash ... ... ... Composition of ash : Lime ... ... Potash ... ... Soda ... ... Sulphates (expressed as sulphuric acid) Chlorides (expressed as chlorine) ... 30.7 21.7 0.2 2.4 16.1 35.2 19.2 0.4 4.0 8.9 30.4 20 -3 0.3 4.1 10 9 34.1 11.5 1.1 8.4 9.1 27.7 16.0 2.4 1-8 7.3 33.2 20.1 2.5 4.7 6.5 Burning quality ...Nature of ash ... Poor. White ; flaky. Poor. White ; flaky. Moderate. Grey ; flaky. Bad. Almost black. Moderate. Dark with grey patches. Poor. Black. A. R. T.FOOD AK’D DRUGS ANALYSIS 501 New Colorimetric Method for the Determination of Vanillin in Flavour- ing Extracts. 0. Folin and W. Denis. (J. Ind. and Eng. Chem., 1912,4,670- 672.)-The Heis-Prescott method, as modified by Winton ( J .Amer. Chem. SOC., 1899, 21, 256; 1902, 24, 1,128; 1905, 27, 719), though accurate, is laborious. By the use of the phosphotungstic-phosphomolybdic reagent (J. Biol. Chem., 1912, 12, 239) an accurate colorimetric method can be employed, which gives theoretical results with arti6cial extracts containing known amounts of the substance, and with authentic extracts gives values identical with those obtained by the official method.The solutions required are (1) an aqueous solution of pure vanillin, 10 C.C. of which contains 1 mgrm. of vanillin ; (2) phosphotungstic-phosphomolybdic acid prepared as follows: To 100 grms. pure sodium tungstate and 20 grms. phosphomolybdic acid (free from nitrates and ammonium salts) are added 100 grms.of syrupy phosphoric acid (containing 5 per cent. H,PO,) and $00 C.C. water : the mixture is boiled over a free flame for one and a half to two hours, cooled, filtered if necessary, and made up fo 1 litre. An equivalent amount of pure molybdic acid may be substituted for the phosphomolybdic acid. (3) Saturated sodium carbonate solution. (4) A solution containing 5 per cent.basic and 5 per cent. neutral lead acetate. Vanillin and other mono-, di-, and tri-hydric phenol compounds, when treated with the reagent (2), give on the addition of excess of sodium carbonate solution the deep blue colour which is the basis of the new method. The method cannot be applied to the untreated extract, since tannin also reacts with the reagent, and the following procedure is required: Five C.C.of the extract to be examined are diluted with about 75 C.C. of water in a 100 C.C. flask, 4 C.C. of the lead acetate solution added, and the mixture made up to volume, filtered, and 5 C.C. of the filtrate placed in one 50 C.C. flask, and in another 5 C.C. of the standard vanillin solution. Five C.C. of the phosphotungstic phosphomolybdic reagent are added to each flask, the solution shaken and allowed to stand five minutes, and then each flask is made up to volume with sodium carbonate solution.The solutions are then well mixed and allowed to stand ten minutes, by which time the precipitation of sodium phosphate is complete. The contents of the flasks are filtered rapidly, and the colour of the filtrates, which must be quite bright, are compared in a Dubosc colorimeter.The standard solution is best placed at 20 mm. Thus, if 5 C.C. of the diluted and filtered solution gave a reading of 18 mm., the result would be 0 . 5 ~ g=O*555 mgrm., and 55*5+250=0*22. Hence 0.22 per cent, of vanillin. An advantage of the method is the small amount of solution required, 2.5 C.C. of extract being enough for from two to four duplicate determinations.The official method may be readily checked by using the ether extract after drying and weighing and dissolving it in ethyl alcohol, the estimation then proceeding as already described. Night readings can be taken, the best illumination being an ordinary incandescent electric light, covered with a sheet of white paper. A new portion of the standard solution should be made for each batch of twelve samples examined, as the colour darkens for an hour after the addition of the alkali.A large number of results are recorded determined by the new and the official methods, which show agreements in all cases within 0.01 per cent. Although vanillin, even in dilute solution, may be precipitated with basic lead acetate, in the high dilution above recommended no precipitation occurs.CoumariD, extract of tonka bean, and acetanilide give no colour502 ABSTRACTS OF CHEMICAL PAPERS with the phosphotungstic-phosphomolybdic reagent, and the presence of sugar, caramel, or glycerol does not interfere with or alter the colour formation. H. F. E. H. Estimation of Extract in Wort and Beer. W.Fresenius and L. Grunhut. (Zeitsch. anal. Chem., 1912, 51, 643-658.)--A comparison is instituted between the tables of Balling, Windisch, Schultze, Ostermann, Elion, and Riiber. For the determination of extract in beer, the table of Windisch is shown to give the least inaccurate values. Windisch's table (" Tafel zur Ermittlung des Zuckergehaltes wassriger Zuckerlosungen," 1896) is a cane-sugar table, and, applied to solutions of maltose and dextrin, leads to results much above the truth, as may be calculated from the results of Brown, Morris, and Millar, or those of Ost or Meissl.But in the case of bser extracts the presence of the small amounts of glycerol and non- volatile acid normally present goes far towards compensating the above error, for these substances are under-estimated by 35 to 40 per cent.if the solution factor for cane-sugar be applied to their solution. The nitrogenous constituents of the extract also tend to reduce the plus errors attaching to the lise of Windisch's table, whilst the ash constitsents tend to increase it. Tho algebraic sum of all the errors is always positive, and appears to lie between 0-4 and 1.2 per cent. The extract of unfermented malt-worts is over-estimated by as much as 2 per cent. if calculated by means of Windisch's table, since the influence of the maltose and dextrin in unfermented wort quite outweighs the influence of the minor con- stituents. Of existing tables, that of Riiber (" Videnska,bsselskabets Skriften I., Mathematisk-naturv. Klasse," 1897, No. 5) gives the smallest errors when applied to unfermented malt worts. The error is a minus one, and its magnitude very close to 1 per cent. Riiber's table being somewhat difficult of access, and occupying several pages in its original form, the present authors have condensed it as follows. The table gives the percentage of extract corresponding to every degree of gravity from 1,000 to 1,085, and the nine columns on the right show the addition to be made for each tenth of a degree. EXTRACT TABLE ACCOXDING TO C. N. RIIBEL (PERCENTAGE BY WEIGHT.) d 15" I 16" 1'00 .. 1.01 . . 1'02 .. 1.03 .. 1-04 .. 1.05 .. 1.06 .. 1'07 .. 1.0s . . - 0 0.00 2'48 4.92 7-31 - 9.67 11.9s 14'213 16.50 LS'i1 - 1 - 0 '25 2.73 5.16 7.55 9'90 12'21 14'48 16.72 1S.93 - 2 0.60 2 9 7 5'40 7.7s 10'13 12'44 14.71 16'95 19.16 - - 5 - 1'25 3 . i O 6-13 s '49 10'83 13.12 15.3s 17-61 19'SO - 6 - 1'49 3'95 8'36 s.73 11'06 13.35 15-61 17'83 - - 7 - 1'74 4 19 6'60 S.96 11%) 13'5s 15%3 1s.05 -. - 8 - 1.99 4'43 6 '64 9'20 11'52 13 'SO 16.06 18.217 - - 9 - 2'24 4-G8 7.07 9.43 11-75 14.03 16-28 18'49 - - 1 - 02 02 02 02 02 02 02 02 02 - 2 - 05 05 05 05 05 05 04 04 04 - 3 - 07 O i 07 0; 07 07 c; 07 07 - 4 - 10 10 10 09 09 00 09 09 09 - 6 - 12 12 12 12 1 2 11 11 11 11 - 6 - 15 15 14 14 1'4 14 13 13 13 - 7 17 17 17 17 16 16 16 15 15 - - 8 - 20 20 1 9 1 I) 1s I S 1s 1s 17 - 9 - 22 22 22 21 21 "1 20 20 20 G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9123700492

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOG [CAI;, ETC. 503 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Structural Elements of Cellular Membranes. J. Konig. (Chena. Zeit., 1912, 36, 1101.)-In addition to true cellulose, the cellular tissue contains-(A) Fat, wax, resin, tannin, aromatic aldehydes, glucosides, etc. ; (B) hemicelluloses ; (C) lig- nins; (D) cutin and suberin. The substances under Group A may be removed by treatment with dilute alcohol or with alcohol, benzene, and ether ; the Group B by hydrolysis with dilute acids; the Group C by feeble oxidisiog agents in alkaline solution; and the Group D by treating the residue from the preceding groups with dilute ammoniacal copper solution or zinc chloride and hydrochloric acid, by which the true cellulose is not attacked.The substance obtained by treating a vegetable substance with dilute acids and alkalis, or with glycerol-sulphuric acid, is not cellu- lose ; it contains large quantities of lignin, together with hemicellulose (pentosan), and is more properly termed (‘ crude fibre ” than cellulose.The (‘ cellulose ” prepared from wood for paper-making contains considerable quantities of pentosan and lignin.By treating rasped wood with dilute mineral acid, followed by oxidation with the usual agents, a comparatively pure cellulose may be obtained, and also by-products which may be used as fodder. When beech or pine wood, or hemp fibre, has been treated with benzene, alcohol, and water, and then subjected to hydrolysis with 72 per cent. sulphuric acid, subsequent treatment with water yields a clear solution and a brownish-black sedi- ment; the latter has the structure of the cell-membrane, and may be oxidised by hydrogen peroxide in ammoniacal solution.It consists of lignin, and in this way not only the cellulose, but the lignin, may be estimated in cellular tissues. It is not considered probable that the lignin is combined with cellulose in vegetable tissues, as, if this were so, the two substances would not preserve their original structure when separated.I t would appear to be likely that the lignin and the cellulose were mixed in the tissue in much the same way that calcium phosphate and proteins exist in bones. w. P. s. Delicate Method for Determining Minute Quantities of Chlorophyll. C. A. Jacobson. (J. Anzer. Chem. SOC., 1912, 34, 1266-1269.)-The author has extended the work of Jacobson and Marchlewski (ANALYST, 1912, 460) in the separation of neo- and allo-chlorophyll, and, modifying the photographic process there described, uses it far the estimation of traces of chlorophyll.The intensity of the chlorophyllan absorption bands in the ultra-violet of the solution to be examined is compared with that of corresponding bands produced by solutions of known concen- tration.Chloroform, as before, is used as the solvent, and 4 or 5 C.C. of solution waa found to be suf5cient for the purpose, containing as little as 0.02 mgrm. of chlorophyll. A leaf whose green weight is 0.2 grm. suffices for determining the quantity and character (b., ratio of neo- to allo-chlorophyll) of the chlorophyll it contains.Eight photographic plates are given, illustrating the variations in intensity of the spectra obtainable. Leaves are macerated in a mortar with cold 92 per cent. alcohol, filtered, and the residue again ground until the extract is colourless. Two C.C. of 10 par cent. alcohol oxalic acid solution is added to the extract, and the whole allowed to504 ABSTRACTS OF CHEMICAL PAPERS stand two or three hours.Calcium carbonate is then added in slight excess, and the mixture evaporated to dryness on the water-bath. The residue is then extracted with chloroform till colourless, and the chloroform solution is diluted appropriately for photographing the spectrum. H. F. E. 13. Nature of Peroxydase. A. Hesse and W. D. Kooper. (Zeitsch. Untersuch.Nahr. Genussm., 1912, 24, 301-309.)-The results obtained during an investigation as to the nature of the substance which yields the " peroxydase " when milk is treated with Rothenfusser's, Storch's, and Arnold's reagents, in the presence of hydrogen peroxide, lead the authors to the conclusion that inorganic substances also play a part in the reaction, and that these substances are not the alkaline constituents of the milk (Cf.ANALYST, 1912, 141). They are of the opinion that the colour reaction is due to the catalytic action of iron compounds such as ferrous lactate. This is borne out by the extreme sensitiveness of the reagents towards ferrous lactate, even in very dilute solutions of the latter, and by the fact that the iron solution loses its property of giving a coloration with the reagents when it has been boiled, either alone or in the presence of milk, or even when it has received the addition of boiled milk.Further, substances such as lactic acid, sodium thiosulphate, ethyl alcohol, methyl alcohol, and amyl alcohol, which prevent the so-called peroxydase reaction, also inhibit the action of ferrous lactate on the reagents, whilst mercuric chloride and chloroform (two substances which destroy enzymes) do not interfere with the reaction, either in the case of milk or of ferrous lactate.w. P. s. Proteolytie Enzyme of Malt. R. Wahl. (Eighth Inter. Cong. App. Chem., 1912, vol. 14, 216-229.)-The proteolytic activity of malt extracts is much increased by the presence of bacterial acidity due to lactic acid, and the author concludes that the peptic enzyme contained in the malt is combined with some base of an albuminous nature, and becomes active through liberation by bacterial acidity.The optimum temperature for the splitting of albumin in presence of lactic acid is about 30" C., and the reaction is rapidly brought to a standstill at about 50" C. It has hitherto been stated that the optimum temperature for peptic activity was from 40" to 50" C.The substitution of mineral or commercial acid for lactic acid of bacterial origin does not result in any increased activity, and this latter acid, when added to a brewer's mash, increases the total yield obtainable from the malt, owing to an increase in peptic activity. Commercialmalts differ greatly as regards their peptic activity, high-dried malts being less active than low-dried.The lactic acid employed for the acidulation of the water used in the malt extractions was prepared by inoculating a mixture of 1 pint crushed malt in 4 pints of water with a culture of lactic acid, and raising to a temperature of 50" or 60" C. for about twenty-four to forty- eight hours, by which time 1 or 2 per cent.of lactic acid is formed. The grains are then separated and the liquid used in suitable dilution for the extraction of the malts under examination. The peptic strength of the extracts was determined by auto- digestion and by a modified '' gelatine liquefying strength " method adopted from that of Schidrowitz (J. Inst. Brewing, 1904,10,166). The peptic strength of malt extracts was always compared with that of a standard solution of pepsin of known strength.BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.505 The gelatine is prepared as follows : 32 grms. of gelatine are dissolved in 318 C.C. of distilled water by gently warming. One-third of a grm. of finely-ground egg albumin dissolved in 50 C.C. of distilled water is then added, and the gelatine solution cooled to 52" C.The temperature is then raised to 85" C. in five minutes, then kept at 100" C. for ten minutes, and filtered into a beaker containing 0.5 grm. of thymol. Tubes are then filled with 6 C.C. of the gelatine solution, and closed with corks to prevent evaporation. When required for use the tube is gently warmed in a water- bath until the contents are liquefied.Five C.C. of the extract to be examined are added, a blank tube being run alongside with 5 C.C. of water. The tubes are incubated for four hours at 3 7 . 5 C., and afterwards placed in ice-water at 2" C., the time required for solidification of the gelatine being noted. The time for the blank tube to solidify is subtracted from that of the other tube, as the lactic acid has it slight liquefying action on gelatine.The pepsin standard is prepared by mixing 0.15 grm. of pepsin of 10,000 strength with 10 grms. of powdered sugar, and dissolving the whole in 100 C.C. of distilled water. Five C.C. of this solution are added to a gelatine tube, and, under the conditions already described, should require seven minutes for solidification. The auto-digestion method consists in measuring the amount of coagulable albumin remaining in the malt extracts after digestion for a suita,ble time and temperature, and is carried out as follows: The clear filtered extract, after the above-mentioned digestion, is heated to 75" C., and kept at this temperature for thirty minutes, when it is cooled to 25" C.Ten C.C. of the solution are then centrifugedfor four minutes at a speed of about 2,500 per minute.The coagulated albumin is then read in ,l,ths of C.C. A number of values are recorded with varying amounts of lactic acid acidity, and also with mineral acids, none of the latter showing a solidification time beyond five minutes, as against the fifteen to twenty minutes with 1.5 to2per cent. lactic acid. Malts containing moisture from 2 to 3.9 per cent.gave gelatine values of sixteen to twenty-one minutes, while from 4 to 6.4 per cent. of water lowered this to about ten minutes. High extract malts also gave a higher gelatine test indicative of greater peptic strength. H. F. E. H. Sensitive Test for the Detection of Albumin in Urine. A. Jolles. (Chem. Zeit., 1912, 36, llOS.)-The reagent employed is prepared by dissolving 10 grills.of mercuric chloride, 20 grms. of citric acid, and 20 grms. of sodium chloride in 500 C.C. of water. Five C.C. of the filtered urine are placed in each of three test-tubes ; the first tube then receives the addition of 1 C.C. of 30 per cent. acetic acid, and 5 C.C. of the reagent, the second tube 1 C.C. of the acetic acid. Water is then added to the second and third tubes until they are filled to the same height as the first tube, and their contents mixed by shaking.On placing tube No. 3 between Nos. 1 and 2, a difference in the turbidity of the contents of the two latter is readily detected ; in the presence of albumin and pus the contents of tube No. 1 will be more turbid than those of tube No. 2. The presence of mucin and nucleo-albumin may be detected by comparison with tube No.3 ; an increase in the turbidity of the contents of tube No. 2 when diluted with water indicates the presence of nucleo-albumin. -it7. P. s. The test will detect 1 part of albumin in 130,060 parts of urine.506 ABSTRACTS OF CHEMICAL PAPERS Detection of Blood in Urine and other Physiological Fluids. F. Michel. (Chem. Zeit., 1912, 36, 994-995.)-The guaiacum test for blood is rendered more sensitive if a small quantity of pyridine is added to the urine or other fluid under examination.Five C.C. of urine should be mixed with about 1 C.C. of pyridine before the ozonized turpentine or hydrogen peroxide is added. The extraction of the urine with pyridine, according to the method described by von Furth for the detection of blood on fabrics (ANALYST, 1911, 36, 549) is in many cases unsatisfactory, as substances are extracted from the urine which interfere with the subsequent test for blood.The following method of carrying out the test is stated to be more trust- worthy, and to be capable of detecting the presence of 1 part of blood in 200,000 parts of uriue : Twenty-five C.C. of the urine (filtered, if necessary) are treated with 5 C.C.of a 15 per cent. calcium chloride solution, and heated to boiling. To the hot solution are added 5 C.C. of a 10 per cent. sodium phosphate solution, the precipitate (consisting of calcium phosphate together with coagulated' blood) is collected on a, filter, washed with a small quantity of physiological salt solution, and a portion of it is transferred to a strong stoppered test-tube.Three C.C. of water, 3 C.C. of pyridine, and a few drops of potassium hydroxide solution are added, and the mixture is boiled. It is then shaken, while hot, with an equal volume of 50 per cent. potassium hydroxide solution, the pyridine layer is separated, again shaken with 50 per cent, solution, and separated. This pyridine solution is now treated with an equal volume of glacial acetic acid, 0.5 C.C.of a leuco-malachite green solution (Cf. ANALYST, 1911, 36, 284), and 2 drops of 1 per cent. hydrogen peroxide. An intense green coloration develops if blood is present. Another portion of the calcium phosphate precipitate may be dissolved in a few drops of glacial acetic acid, treated with a small quantity of pyridine, and then tested with the leuco-malachite green solution in the presence of hydrogen psroxide.I n both testa the coloration must develop within two minutes, and be of a deep tint ; a faint green coloration, which does not indicate the presence of blood, is given by the calcium phosphate precipitate obtained from most normal urines. w. P. s. Estimation of Cane-Sugar in Urine in the Presence of Other Sugars.A. Jolles. (Biochem. Zeitsch., 1912, 43, 56-64.)-The method described previously by the author (Cf. ANALYST, 1911, 36, 28) may be applied to the estimation of cane-sugar in urine under the following conditions : Urine containing less than 5 per cent. of dextrose is diluted with an equal volume of water, but when the dextrose exceeds 5 per cent.it is necessary to dilute 1 volume of urine with 2 volumes of water. Of the diluted urine, 100 C.C. are treated with 2.5 C.C. of a 16 per cent. sodium hydroxide solution, and then maintained at a temperature of 37" C . for twenty-four hours. After cooling, the mixture is rendered slightly acid with acetic acid, and 50 C.C. are mixed with 5 C.C. of 10 per cent. lead acetate solution, filtered, and the filtrate is examined with the polarimeter.A slightly negative reading (about - 3" Ventzke) indicates that cane-sugar is absent, whilst a positive reading shows that this sugar is present in the urine, and its quantity may be calculated from the reading observed, allowance being made for the extent to which the urine has been diluted. As little as 0.2 per cent. of cane-sugar may be detected in urine by meansBACTERIOLOGICAL, PHYSIOLOGICAL, ETC.507 of the method. Trustworthy results cannot, however, be obtained in the case of wines containing a large quantity of ammonium salts, or of P-hydroxybutyric acid or other optically active substance. w. P. s. Deteetion of Laevulose in the Presence of Dextrose. A. Jolles. (Chem.Zeit., 1912, 36, llO8.)-The author’s modification of the Ihl-Peckmann reaction will detect the presence of 0.1 per cent. of laevulose in urine which also contains 5 per cent. of dextrose. The test is carried out as follows : 1 C.C. of diluted urine (1 : 10) is treated with 10 drops of a 20 per cent. alcoholic solution of diphenyl- amine and 1 C.C. of concentrated hydrochloric acid, and the mixture is boiled for fifty seconds.A comparison test should be made ah the same time with normal urine, containing a similar quantity of dextrose. The detection of pathological con- stituents in urine is rendered difficult owing to the increasingly large number of substances which are administered as medicines. For instance, a sample of urine was found to be laevorotatory, yielded positive reaction with phenylhydrazine and Seliwanoff’s test, but failed to give the Ihl-Pechmann reaction, and a fermentation test gave a negative result.This urine was from a patient who, for three weeks, had been taking validol (a compound of menthol with valerianic acid). w. P. s. Detection of Glycuronic Acid in Diabetic Urine. A. Jolles. (Chem. Zed. 1912, 36, 1108.)-Since dextrose gives a reaction with naphthoresorcinol, it is not possible to detect glycuronic acid directly in diabetic urines by means of this reagent.The test may, however, be carried out 8s follows : From 200 C.C. to 400 C.C. of the urine are treated with lead acetate until a precipitate no longer forms; after settling, the clear solution is passed through a filter and the precipitate is washed four successive times by decantation with water, using 400 C.C.each time. The filtrate (excluding the washings) is now precipitated with basic lead acetate, and this precipitate is washed in a similar way. The two precipitates are united, mixed with a small quantity of water, heated to 70’ C., the lead is removed as sulphide, and the solution is evaporated to 20 c.c.; 5 C.C.of this solution are then tested with naphthoresorcinol. w. P. s. Method for the Estimation of Hippuric Acid in Urine. T. Hryntschak. (Biochem. Zeitsch., 1912, 43, 315-322.)-The method is based on the oxidation of hippuric acid by permanganate, the resulting benzoic acid being separated sub- sequently by extraction with ether. One hundred C.C. of the urine are boiled with 10 grms.of sodium hydroxide in a flask (about 1 litre capacity) under a reflux condenser for one hour. The contents of the flask are then cooled, the condenser is removed, and potassium permanganate is added, in small quantities at a time, until the liquid has a distinct permanganate tint after a further seven minutes’ boiling ; in the case of human urine, 10 grms.of permanganate is usually a sufficient quantity. The mixture is again cooled, a few pieces of ice are added, together with about 15 grms. of sodium bisulphite. The condenser is attached to the flask, the latter is placed in a vessel of cold water, and 50 per cent. sulphuric acid is added through the condenser until all the manganese dioxide has dissolved. The flask may508 ABSTRACTS OF CHEMICAL PAPERS now be placed aside for a few hours and the contents then extracted five successive times with ether, the condenser and the flask being also rinsed with the solvent.The united ethereal extracts are dried by the addition of fused sodium sulphate and transferred to a round glass basin, the last portion of the ethereal solution being decanted through a small filter in order to remove fragments of sodium sulphate.After the ether has been evaporated the residue is dissolved in a, small quantity of chloroform (previously washed with water and dried over anhydrous copper sulphate), the solution is filtered into a weighed flask, and the chloroform is evaporated by placing the flask in a vessel through which a current of dry air is passed. The weight of the benzoic acid found is multiplied by 1.468 to give the amount of hippuric acid present. Results of experiments are recorded which show that, when hippuric acid is added to urine, from 96-1 to 99.9 per cent. of the amount introduced may be recovered by means of the above-described method, provided that an allowance is made for the quantity of benzoic acid yielded naturally by different urines when subjected to the process. In the case of human urine the benzoic acid found amounts to 0.056 grin. per 100 C.C. ; with dog’s urine it is 0.009 grrn., and for horse’s urine 1.007 grms. The presence in urine of such substances as hydroxyphenyl- acetic acid, hydroxyphenylpropionic acid, phenylaceturic acid, and of benzoic acid contained in a, glycocoll complex, will influence the results, but, as a rule, these substances occur in such small quantity that their effect may be neglected. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700503

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

508 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Elementary Analysis. A. Kwrtenacker. (Zeitsch. anal. Chem., 1912, 51, 639-640.)-The author recommended (ANALYST, 1911, 36, 516) the use of reduced nickel in the forward part of a combustion-tube to reduce oxides of nitrogen. Doht (Zeitsch. anal. Chenz., 1911, 50, 755) criticised that paper on the ground that its author rejects the use of metallic silver for the same purpose, without adducing any evidence of its failure to reduce oxides of nitrogen and without reference to the work of Epstein and Doht (Zeitsclz.anal. Chem., 1907, 46, 771), who recommended it. The author now points out that in his original paper he gave references to the work of others who had shown the insufliciency of silver, brings forward experimental evidence of his own to the same effect, and shows that the work of Epstein and Doht is inconclusive, since many of the test substances used by them-e.g., p-nitraniline and m-dinitroberzene-give accurate results when sub- mitted to combustion in an open tube without the use of any device for the reduction of oxides of nitrogen.G. C. J. Estimation of the Acetyl Value. W. Normann.(Chent. Rev. Fett- u- Haw-Ind., 1912, 19, 205-206.)-The following rapid method obviates errors caused by esterification of acetylated fatty acids when dissolved in hot alcohol : About 2 grms. of the filtered fat are weighed into a saponification flask and boiled with 4 to 6 C.C. of acetic anhydride for thirty minutes to an hour beneath a reflux condenser. The flask is then immersed in a hot-water bath, while a current of carbon dioxideORGANIC ANALYSIS 509 hydrogen (or air in the case of non-oxidisable fats) is blown through it, until the whole of the residual acetic anhydride has evaporated.The contents are next diluted with a little ether, about 5 C.C. of water added, any remaining traces of acetic anhydride and the free fatty acids neutralised with a few drops of aqueous sodium hydroxide solution, and the fat saponified with 50 C.C.of alcoholic potassium hydroxide solution, the excess of which is titrated with $ hydrochloric acid. The amount of alkali expressed in the usual way gives the value for the saponification of the glycerol ester and of the acetic ester. By deducting from this value the saponifica- tion value of the original fat, if neutral, or the ester value if free fatty acids were present, a value is obtained showing the amount of alkali corresponding to the free hydroxyl groups in the original fat.For this the term hydroxyl value is suggested in contradistinction to the acetyl value, which only relates to the acetylated fatty acids. C. A. No Hubener Bromide Method for the Estimation of Caoutchouc.R. Becker. (Gummi-Zeit., 1912, 26, 1503 ; through Chem. Zentralbl., 1912, II., 966.)-The Hiibener bromide is not entirely soluble in chloroform (cf. Hinrichsen and Kindscher, ANALYST, 1911, 31, 224), but is dissolved completely by a mixture of chloro- form and carbon disulphide. Caoutchouc brominated by the method of Budde did not show this peculiarity. The proportion insoluble in chloroform increases with the amount of bromine in excess during the bromination.The substance insoluble in chloroform is of a sticky consistency, and may easily be taken for unconverted caoutchouc. The author considers that the error thus introduced into the Hiibener method can be avoided by bringing the rubber into less intimate contact with the bromine; this is effected by placing the bromine in a special stoppered porcelain vessel pierced with fine holes at 5 to 10 mm.from the bottom. This is removed from the beaker when the powdered bromide is returned to it. The bromine may also be the cause of the oxidation of vulcanisation sulphur. The presence of sulphur trioxide in the bromine, mentioned by Hiibener, is confirmed. 0. E.M. Hubenor Bromide Method for the Estimation of Caoutchouc. G. Hubener. (Gummi-hit., 1912, 26, 1711 ; through Chem Zentralbl., 1912, II., 967.)-The sticky substance insoluble in chloroform, observed by Becker (see preceding abstract), may be due, not to over-bromination, but to the presence of compounds of bromine or oxygen with resins, or of the resins themselves, as Becker does not state that these had been removed from the rubber.Pure tetrabromide is not always obtained by the method of Budde (ANALYST, 1909, 34, 407) Korneck (ibid., 1911, 36, 158) found that it often contains enclosures of unaltered rubber, and, as Speiice and Galetly have shown (ibid., 1911, 36, 361), the whole of the protein is present. On the other hand, Utz (ibid., 1912, 361) obtained a bromide containing 70.18 per cent.of bromine- a nearly theoretical result. Regenerated rubber, containing more constituents soluble in acetone, yields more substance insoluble in chloroform than does raw rubber; but this comes not wholly from resin and oil, but also from the caoutchouc-sulphur compound which at present cannot he broken up in the process of regeneration. The author’s modified method is as follows : The rubber is rasped fine, and 2.5 grms.510 ABSTRACTS OF CHEMICAL PAPERS are wrapped in filter-paper and extracted in a Soxhlet apparatus with acetone for from four to six hours.If resin insoluble in acetone is present, as in hard rubber mixtures, an extraction with dichlorhydrin follows. The residue is dried at 60” C., and 0.2 grm., or more if necessary, digested with 100 C.C.of water and 5 to 10 C.C. of bromine at a moderate temperature on the sand-bath, until the rubber is completely opened out and most of the bromine driven off. The rest is removed by boiling. The precipitate is washed on a filter with hot water, dried at 50” to 60” C., and fused at a, red heat in a platinum crucible with sodium carbonate free from halogen. The melt is dissolved by warming in aqueous nitric acid; overheating must be avoided.The bromine is then titrated (Chem. Zeit., 1909,33, 648). An analysis in which extraction with acetone was omitted gave a result exceeding the theoretical by 3.5 per cent.; this is regarded as satisfactory, as the acetone extract was especially high. The author’s method is suitable only for vulcanised rubber.0. E. M. Estimation of Cellulose in Woods and Textile Fibres. C. F. Cross and E. J. Bevan. (Zeitsch. f. Farbenind., 1912, 11, 197-198 ; through Chem. Zentralbl., 1912, II., 1066.)-In a paper by Konig and Huhn (Zeitsch.f. Farbenind., 1911,10,297), it was contended that Cross and Bevan’s chlorination process is one of oxidation by which considerable residues of pentosans and other bodies differing from true cellulose are left in the product, whilst the cellulose itself is appreciably modified by oxidation.Kiinig and Huhn recommended in preference a process consisting, first, of a hydrolysis with sulphuric acid dissolved in glycerol, whereby pentosans and hemihexosans are hydrolysed and dissolved, and, secondly, of an oxidising treatment (hydrogen peroxide and ammonia) whereby lignin is removed.The present authors condemn such a method on the ground that the products ob- tained are residues of hydrolysis and degradation, and bear no definitely ascertained quantitative relationship to the original material. The main characteristic of a ‘‘ normal ” cellulose is its quantitative persistence through a cycle of chemical changes-e.g., (a) Nitration-denitration, or ( b ) conversion into xanthogenate-reversion to cellulose, with all its colloidal structural properties unchanged.The chlorination of lignin complexes is a specific reaction, and secondary oxidation changes in the cellulose residue may, under proper conditions, be almost entirely suppressed. The authors do not accept the view that the production of furfural from the celluloses isolated by their method indicates the presence of pentosan non-celluloses as residual (‘ impurities.” This is supported by the fact that the celluloses isolated from the Gramineae, by drastic and purely hydrolytic processes (caustic soda), yield 12 to 14 per cent.of furfural, which it is impossible to regard as being derived from adventitious pentosans.Thus, Konig and Hiihn’s contention that cellulose, which contains furfural-yielding groups, has not been sufficiently purified by hydrolysis, is untenable. J. P. B. Estimation of Cellulose in Woods and Textile Fibres. J. Konig and F. Huhn. (Zeitsch. f. Farbenind., 1912,11,209-211; through Chem. Zentralbl., 1912, II., 1066-1067.)-The authors reply to the specific points raised by Cross and Bevan (see preceding abstract). They state that Cross and Bevan have not proved thatORGANIC ANALYSIS 511 chlorination is unaccompanied by oxidation.They rely on the work of Tollens in support of their contention that furfural-yielding groups are synonymous with pentosans, which they contend must be removed by still more drastic hydrolysis before the cellulose can be considered pure.The maximum specific rotation of solutions of cellulose in acid zinc chloride was not put forward as a test for pure cellulose, but the fact was merely recorded that the solutions which showed the maximum rotations were derived from celluloses which, by other characters, were proved to be the purest. Konig and Huhn found by their proposed method, in a sample of commercial sulphite wood cellulose, only 32.21 per cent.of '' true cellulose "; this result is upheld against the criticism of Cross and Bevan on the ground that the sample still contained much lignin. The differences between the authors and Cross and Bevan turn on the question of a definition of chemically pure cellulose, as contrasted with the technically pure article.Konig and Braun, by the isolation of lignin, free from accompanying cellulose, but still retaining the structural form of the cell membrane, have proved that the lignocellulose of wood is not a chemical combination, but a mixture of two mutually interpenetrating colloids. J. F. B. Determination of Bleaching Quality of Sulphite Pulp. E. Richter. (Eighth Inter.Cony. App. Chem., 1912, vol. 13, 233-236.)-The author has previously shown that the Hempel-Seidel nitric acid figure of pulp can be employed to determine the percentage of non-cellulose in pulp, jute, or wood, by previously extracting the pulp with ether, alcohol, and water. The nitric acid figure gives values proportional to the bleach test, and an attempt has been made by a colorimetric method to gee.a value in per cent. of bleach powder. Sulphuric acid which has been employed by Klason (Papier Zeit., 35, 3781) as the basis of a, colorimetric method for this purpose is unsatisfactory, since this acid attacks too much pure cellulose. The author recom- mends the following procedure: 5 grms. of air-dried pulp are broken up in thin pieces and placed in a widemouthed bottle with 100 C.C.of 13 per cent. nitric acid, well shaken, and kept in the dark for an hour. A standard pulp of known bleaching quality is put on alongside. At the end of the hour the mass is filtered through a, small piece of pure absorbent cotton on a dry funnel, and 25 C.C. of the filtrate from each transferred into small bottles. From zt burette water is added to the darker one until the shade of both solutions is the same.The colours can then be accurately compared in Eggertz carbon tubes. The bleaching quality of the pulp to be tested is calculated by simple proportion from the amount of bleaching powder that is known to be required for the standard. A strongly digested pulp will not always yield much colour to the acid in one hour, but placing the water-bottles in a water-bath a t 40' C.and shaking will bring out the colour in about fifteen minutes, and the comparison can then be proceeded with. H. F. E. H. Detection and Determination of Cyanogen and Hydrogen Cyanide. F. H. Rhodes. ( J . Ind. and Eng. Chem., 1912, 4, 652-655.)-The author has examined, from the quantitative point of view, the observation of Wallis (Ann.Chem., 1906, 345, 353), that while hydrogen cyanide in the presence of cyanogen is quantitatively precipitated when passed through acidified silver nitrate solution,572 ABSTRACTS OF CHEMICAL PAPERS cyanogen may be removed from solution in this reagent by a current of air. He finds that hydrogen cyanide and cyanogen may be determined accurately in the presence of each other, the former being precipitatcd as silver cyanide in acid silver nitrate solution (10 per cent.with 7 drop of dilute nitric acid), while the cyanogen which passes on may be detected and estimated colorimetrically by collecting it in caustic potash solution, adding ferrous sulphate and 1 drop of ferric chloride, and then, after fifteen minutes, acidifying with dilute sulphuric acid.I n this manner as little as 0.3 C.C. of cyanogen can be detected in a mixture of the two gases, and in the presence of large volumes of air. Carbonic acid does not interfere unless present in such quantity as to form potassium carbonate with the whole of the caustic potash employed. If the quantity of hydrogen cyanide is very small, ths trace of silver cyanide obtained can be filtered off and sublimed with a trace of iodine in a tube, when as little as 0.1 mgrm.of silver cyanide, equivalent to 0.02 mgrm. of original hydrogen cyanide, can be detected as a sublimate of cyanogen iodide. H. F. E. H. Estimation of Dextrose in the Presence of other Optically Active Substances by Bertrand's Method. M. Rosenblatt. (Biochem. Zeitsch., 1912, 43, 478-480.)-When it is desired to estimate dextrose in a solution containing, in addition, such substances as peptones, amino-acids, etc., by the polarimetric method, it is necessary to remove these substances previously by means of mercuric acetate and phosphotungstic acid (Cf.ANALYST, 1912, 145). Such is not the case, however, when the sugar is estimated by Bertrand's method (ANALYST, 1908, 33, 476), as the results obtained are not affected to any appreciable extent by the presence, in the sugar solution, of glycin, alanin, leucin, tyrosin, asparagin, betaine, glutamin, urea, and peptone.This particularly applies to the estimation of dextrose in urine, for which purpose the polarimetric method is unsuitable, owing to the small quantity of sugar present. Urea and peptone have the most influence on the results obtained by Bertrand's method, the amount of sugar found being too low by from 1.6 to 4.4 per cent.of the quantity actually present. I t is pointed out that the ferric sulphate solution used in Bertrand's method should contain 50 grms. of ferric sulphate and 200 grms. (not c.c.) of concentrated sulphuric acid per litre. w. P. s.Diphenylamine Test for Gun-Cotton. C. Kullgren. (Zeitsch. f. Schiess- 26. &rengstofwcsen, 1912, 7, 153.)-Guttmann's test consists in maintaining the dried nitrocellulose at 80" C. in a tube in which is suspended a strip of dipheriylamine test-paper, and taking as a measure of the stability of the sample the time required for the evolution of oxides of nitrogen sufficient to produce a blue tint on the paper.This investigation is to determine whether the acid substances producing this colora- tion exist ready-formed in the gun-cotton, or whether they are produced during the heating. The experimental material was a factory gun-cotton containing 12.6 per cent, of nitrogen, and dried at 40" to 45" C. for sixteen hours. Free acid in gun- cotton may be either the remains of nitrating acid not removed in manufacture, or the result of slow decomposition at ordinary temperatures; it was found that washingORGANIC ANALYSIS 513 before the test had no effect if the sample was dried, because the acid is in any case driven off by drying at 45" C.This was supported by the observation that gun-cotton moistened with strong mineral acids recovered its test with sufficient drying; that drying at 45" C.gave rise to a much higher test than drying over phosphorous pent- oxide or sulphuric acid at room temperature; and that a gun-cotton, insufficiently stabilised by boiling, gave a much higher test after being dried at 45' C. for two days than it did after standing for fourteen days at ordinary temperature, and drying for three hours at 45OC.The test is thus dependent, not on the free acid present in the gun-cotton, but on that produced during the test (qf. Robertson and Smart, Zeitsch. f . Schiess- 26. Sprengstofzuesen, 1910, 5, 185: 208). The danger of obtaining fallacious tests due to traces of unstable bodies may be avoided by prolonging the time of dry- ing, and taking tests at intervals.The decomposition of nitrocellulose is stated to take place in at least two stages, the velocity with which the intermediate body or bodies cause the evolution of oxides of nitrogen being increased more rapidly by rise of temperature than their velocity of formation. The test would then depend, not on the total amount of unstable constituents, but on the amount of intermediate product.Prolonged drying at 45' C. would diminish the amount of intermediate product, with a high test as the result ; standing at ordinary temperatures would increase it, and a lower test would be produced. 0. E. M. Gasometric Estimation of Ether and Chloroform Vapours in Air. M. Koehmann and W. Streeker. (Biochern. Zeitsch., 1912, 43, 410-417.) - The quantity of ether or chloroform vapour in air may be estimated by shaking the gaseous mixture with alcohol and noting the decrease in volume of the former.The most suitable apparatus to use is a Bunte burette, and 96 per cent. alcohol is employed for the absorption. After the vapours have been absorbed, the alcohol vapour remaining in the burette is removed by means of water saturated with air. The necessary allowance is made for the vapour-pressure of water in calculating the decrease of volume due to the absorption of the ether or chloroform vapour, and full details as regards manipula.tion are given in the original paper.I t may be mentioned that, in some preliminary experiments, olive oil and paraffin were used to absorb the ether and chloroform vapours, but the results obtained were unsatisfactory, owing to the formation of numerous small bubbles of air in the oil during the shaking part of the process.w. P. s. Determination of Humus in Hawaiian Soil. W. P. Kelley and W. MeGeorge. ( J . Ind. uizd Eng. Chenz., 1912, 4, 664-667.)-The author defines hgmus as the organic matter of soils soluble in 4 per cent. ammonia after removing calcium and magnesium with hydrochloric acid, and in the analyses given varies from 2.6 to 18.3 per cent., when estimated by the method described in the paper.A large number of soils were tested for humus content by the following methods, and the results tabulated : Hilgard, Mooers-Hampton, Houston-McBride (official), Cameron- Breazeale, and Rather. I n addition the author describes a modification of his own, involving the filtration, under diminished pressure, of the humus solution through a514 ABSTRACTS OF CHEMICAL PAPERS Pasteur-Chamberland filter, in order to separate the clay, the presence of which in soils containing much of it constitutes the most serious difficulty in the way of accurate determinations (cf.ANALYST, 1912, 466). When the first portion of the solution has passed the filter, 4 per cent.ammonia is drawn through as long as any colour is shown, and the filtrate and washings are then evaporated to dryness. The clay is washed out of the inside of the candle with a test-tube brush between each washing. The candle, with a short portion of its neck protruding, is suspended in a bell-jar from which the air is exhausted, the filtrate collecting in a jar beneath, while the solution to be filtered is poured into the candle down its centre from out- side the bell-jar.Higher results are obtained by this process than by any of the others, excepting the official and Rather methods, neither of which is to be relied on for Hawaiian soils, as the majority of these are rich in very finely divided clay. The cause of the inaccuracy of these two last-mentioned methods becomes clear when the ash is determined in the humus obtained by evaporating its solutions to dryness, the value rising to as high a figure as 33 and 25 psr cent.respectively, as against 0.6, 0.4, and 0.3 per cent. by the other methods. The large amount of clay un- removed from the humus solution accounts for the higher values. H. F.E. H. Estimation of Methyl Alcohol in Admixture with Aleohol, and Especially in Spirits. W. Koenig. (Chem. Zeit., 1912, 36, 1025-1028.)- The following modification of the bichromate method of Thorpe and Holmes (ANALYST, 1904, 29, 113) is recommended as the most generally applicable. The oxidation is effected in a litre flask (previously cleansed with boiling potassium permanganate solution and dilute sulphuric acid), and the carbon dioxide is conducted through drying-tubes, one containing sulphuric acid on pumice-stone, and the other calcium chloride, and is absorbed in two weighed U-tubes containing soda-lime, whilst beyond these are two more guard-tubes containing soda-lime, and calcium chloride.The oxidation flask is closed with a rubber cork with two openings, through one of which passes a dropping funnel, which can be closed at the top by a soda-lime tube, whilst the other opening receives a reflux condenser connected at its other end with the series of absorption tubes.After a current of air (freed from carbon dioxide) has been swept through the apparatus, the mixture of alcohol and methyl alcohol (5 to 10 c.c.) is introduced into the flask, and the dropping-funnel charged with a solution of 30 grms.of potassium bichromate in 500 C.C. of water and 50 C.C. of sulphuric acid (sp. gr. 1-84), this liquid having been first boiled for fifteen minutes and then cooled to 5 O C. After this has also been introduced, the oxidation flask is shaken and allowed to stand for four hours, and its contents then slowly heated and boiled for one hour.Air is next drawn through the apparatus for about forty-five minutes, at first slowly, and then more rapidly, and the absorption tubes are then weighed. The weight of carbon dioxide multiplied by the factor 0.728 gives the amount of methyl alcohol. In test experiments with pure ethyl alcohol the amount of carbon dioxide corresponded to an average proportion of 0.50 per cent.of methyl alcohol-a result that agreed well with the observation of Thorpe and Holmes. The alcohol distilled from spirits behaved in the same way as pure alcohol, and in the case of test-mixtures containingORGANIC ANALYSIS 515 from 4 to 15 per cent. of methyl alcohol the amounts found agreed within kO.19 per cent. of the theoretical quantities. C.A. M. Rapid Methods for determining Phenol. I. V. Redman and E. 0. Rhodes. (J. Ind. and Eng. Chem., 1912,4,655-659.)-The authors compare the bromide-bromate method of Koppeschaar (Zeitsch. anal. Chem., 1876, 15, 233) with the hypobromite method worked out by Lloyd (J. Amer. Chem. SOC., 1905, 27, 16). A special shaking machine was employed, and it was found that, using either method, phenol determin- ations could be made within an error of 0.3 per cent.with one minute of continuous shaking after the solution containing the bromide was added, in place of the usual thirty minutes. It is important that the phenol solution be diluted until approxi- mately &., and under these conditions the precipitate obtained by either method was white and flocculent, and showed no trace of red tetrabromo-phenoyuinone or yellow tribromophenol bromide.The phenol solution employed must be acid after the bromine is added; if alkaline, an error arises, which increases as the concentration of the phenol present diminishes and the reaction period increases. The error introduced by shaking the solution for only one minute after the potassium iodide solution is added before titrating back with thiosulphate is 0-5 per cent.Three minutes shaking eliminates this, and further shaking has no effect. The potassium bromide-bromate solution (3-5 grms. bromate and 55 grms. of bromide to the litre) bas the advantages over the -& hypobromite solution that it is permanent in strength and is free from unpleasant odour and free bromine, and only requires standardising once in three months, whereas the hypobromite solution weakened one-third per cent. every twenty-four hours for the first few days after being made.H. I?. E. H. ‘‘ Acid Resins ” from Petroleum Residues. F. Schwarz. (Clzem. Rev. Fett- u. Ham.-Ind., 1912, 19, 210-212.)-The acid residues obtained in refining the lighter distillation products of petroleum with sulphuric acid yield when diluted with water resinous substances which are used in the manufacture of varnishes, etc., while the acid is regenerated.I n the cases of lubricating oils, however, the mineral acid cannot be separated in this way, and the residues are therefore neutralised with lime and used as asphaltum substitutes. As these products from the so-called (( acid resins ” are inferior to other asphalt materials, it is desirable to distinguish them from the more valuable distillation residues of petroleum.Samples of the former examined by the author yielded aqueous extracts which were strongly alkaline, owing to the presence of free lime. The presence of sulphonated acids was indicated by extracting the sample with petroleum spirit, evaporating the extract, igniting the residue, and testing the ash for sulphuric acid.I n each case a small amount was found. For the separation of the organic acids, 5 grms. of each sample were thoroughly extracted in a basin on the water-bath with a mixture of absolute alcohol and a little hydrochloric acid (sp. gr. 1*19), and the extracts united, cooled to the ordinary temperature, and decanted from the residue.The clear brown liquid was then diluted with an equal volume of water, rendered alkaline with sodium hydroxide, and treated with petroleum spirit, to separate unsaponifiable516 ABSTRACTS OF CHEMICAL PAPERS matters, after which the alcohol was evaporated from the alcoholic solution, and the residual aqueous solution shaken with ether and a little hydrochloric acid, On washing the ethereal layer with water, part of the organic acids was taken up by the water-this being an indication of the presence of sulpho-acids.The hydrochloric acid was therefore eliminated by washing the ethereal solution with a concentrated solution of sodium chloride, and the ether then evaporated. The residual acids were brown and resinous. They dissolved in water, forming a clear brown solution, but were only sparingly soluble in petroleum spirit and benzene. When neutralised and ignited they left an ash containing sulphuric acid. The amounts of sulphonated acids thus separated from three commercial samples were 7.5, 0.86, and 3.5 per cent. respectively. A distillation residue from petroleum treated in the ~ a m e way yielded only an insignificant quantity of a yellow, resin-like mass which was insoluble in water. C. A. M. General Method for the Estimation of Tartaric Acid. A. Kling and D. Florentin. (Bull. SOC. Chiin., 1912, 11, 8%-895.)-The addition of ammonium citrate prevents the interfering action of iron and aluminium salts on the estimation of tartaric acid as calcium racemate (cf. ANALYST, 1910, 35, 323), even when the quantity of iron oxide or alumina present in certain pharmaceutical preparations amounts to 50 per cent. of the amount of tartaric acid. The effect of copper and antimony salts on the estimation is also prevented by the addition of ammonium citrate. The quantity of citrate added should be about ten times the weight of iron oxide or alumina present. When the proportion of alumina is very large, it is better to remove it by precipitation in the form of ammonium-alum. Fm this purpose the tartaric acid solution is treated with ammonium sulphate, a small quantity of hydrochloric acid, and alcohol; the alum crystals are collected on a filter, washed with alcohol, and the tartaric acid is estimated in the filtrate. Large quantities of iron are removed as sulphide in acetic acid solution. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700508

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

516 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Titration of Copper Salts with Titanous Chloride. L. Moser. (Chew. Zeit., 1912, 36, 1126-1127.)-1n the titration of copper salts by means of titanous chloride (see Rhead, J. Chenz. Xoc., 1906, 89, 1491) the use of thiocyanate and of a ferrous salt as indicator may be dispensed with. The reaction only proceeds quanti- tatively in strongly acid solutions, and hydrochloric acid is preferred because cupric solutions containing much hydrochloric acid possess a high colour, and the disappear- ance of this colour marks the end-point of the titration.For the same reason the author makes use of less dilute eolutions than Rhead, a i> solution of titanous chloride being employed, and the copper solution concentrated to approximately strength and mixed with its own bulk of recently boiled hydrochloric acid (1 : 1) before the titration, which must be conducted in a vessel through which 8 current of carbon dioxide passes.The method is accurate to within 0.05 C.C. of the standard titanous chloride. G. C. J.INORGANIC ANALYSIS 517 Detection and Estimation of Minute Quantities of Fluorine in Waters, Minerals, and Living Tissues.A. Gautier and P. Clausmann. (Bull. SOC. Chim., 1912, 11, 872-884.)-The fluorine is first concentrated by rendering the water slightly alkaline, adding about 0.4 grm. of sodium sulphate together with a slight excess of barium chloride, and evaporating the whole to dryness. The residue is treated with a quantity of water sufficient to dissolve the soluble salts, an equal volume of 96 per cent.alcohol is added, the precipitate is separated by centrifugal action, and washed with alcohol until free from chlorides. I n the case of minerals, those which are entirely attacked by sulphuric acid may be tested directly, whilst others are fused with sodium carbonate, dissolved in water, the silica is separated by means of ammonium carbonate, and the solution concentrated.Organic tissues are ignited in the presence of lime, the rzsidue is dissolved in dilute hydrochloric acid, and the solution treated as in the case of water. When a mineral water containing much sulphate is under examination, magnesium chloride, ammonium phosphate, and ammonia may be added, and the precipitate produced employed for the test.The barium, or other precipitate, obtained as described above, is now heated with concentrated sulphuric acid in a specially constructed gold crucible in such a way that the evolved gases are absorbed by moistened potassium hydroxide contained in a device which covers the crucible. At the end of two hours the potassium hydroxide is dissolved in water, the solution is brought just to boiling, nearly neutralised with hydrochloric acid, and ammonium chloride solution is added until the mixture, while still hot, is neutral to phenolphthalein.About 4 grms. of ammonium carbonate are then added, the solution is evaporated to dryness, the residue is dissolved in water, filtered, sodium sulphate is added to the filtrate, which is now heated to boiling, and precipitated with a slight excess of barium nitrate. The mixture is again evaporated to dryness, water is added, together with an equal volume of alcohol, the precipitate is separated by centrifugal action, washed with 65 per cent.alcohol until the last traces of nitrate and chloride are removed, then dried and weighed. A portion of this precipitate may be tested for the presence of fluorine by heating it with sulphuric acid and noting whether the vapours will etch glass.A lead crucible is used in this test, a varnished glass-cover having a small unvarnished portion being employed to cover the crucible. The quantity of fluorine present is estimated in the remaining part of the weighed precipitate by heating the latter with sulphuric acid in a platinum crucible, and absorbing the vapours by powdered lead-glass moistened with water.The lead-glass is then dried, and washed with boiling 85 per cent. alcohol; the lead fluoride is dissolved by washing the lead-glass with a saturated potassium chlorate solution diluted with four times its volume of water, and, after the addition of a small quantity of gelatin solution, $he lead is estimated colorimetrically as sulphide, its quantity being a measure of the amount of fluorine present.I t is stated that the method will estimate accurately as little as 0.1 mgrm. of fluorine in 1 litre of water, or 100 grms. of vegetable or animal tissue, whilst the qualitative test, described will detect as little as 0.001 mgrm. of fluorine. w. P. s. Sampling Gold Bullion. F. P. Dewey. (Eighth Inter.Cong. App. Chem., 1912, Vol. I, 155-181.)--In many cases a chip or drill sample may be satisfactory, in518 ABSTRACTS OF CHEMICAL PAPERS others, drillings will give a more representative sample than chips. But with bullion concerning which nothing is known the sample must be remelted, properly mixed, and dipped. I n many cases, particularly of cyanide bullion, the composition of the metal interferes with the actual assaying, and the bullion must be refined before the gold can be determined accurately.The paper includes the results of hundreds of assays which support the above conclusions. The degree of divergence between duplicates, when remelting is dispensed with, may be as much as 1 per cent. G. C . J. Estimation of Hydrogen and Methane in Gas Mixtures.W. Hempel. (Zeztsch. angew. Chem., 1912, 25, 18&1-1845.)-The temperature obtainable by means oE an ordinary Bnnsen burner is insufficient to ensure complete combustion oE methane in a Drehschmidt platinum capillary. The use of a small blowpipe flame is essential. The Drehschmidt platinum capillary may be replaced by a capillary of transparent quartz, into which is pushed a short length of platinum wire oE such diameter that the wire almost fills the tube.Such a capillary has the advantage that there is no risk of propagation of flame from the heated portion of the capillary to an explosive mixture contained in the gas burette to which it is connected. When using the Winkler-Dennis combustion pipette there is often difficulty in burning the last of the methane, so that the operation extends over a considerable period, during which such an amount of mercury may be oxidised as to give rise to serious error. This source of error may be avoided by enclosing the electrically heated spiral in a quartz glass tube, which becomes the outer limb of the capillary U-tube of a simple mercury pipette.The gas is passed slowly to and fro between the burette and pipette over the heated spiral.The quartz tube is connected at either end by short pieces of rubber tubing to the tubes of soft glass, through which pass the stout platinum wires conveying the current to the spiral. A detailed drawing of a convenient arrangement accompanies the paper. Fractional combustion of hydrogen by means of palladium asbestos is successful only if the passage of gas through the capillary be slow and the temperature of 400" C.not exceeded. A convenient way of controlling the temperature is to let the capillary containing the palladium asbestos lie horizontally in a groove cut in a massive block of brass, which is heated by a flame. Close to the groove in the block is bored a vertical hole which accommodates a thermometer or a tube of mercury, the boiling of which shows that a suitable temperature has been reached. The author uses a capillary of 1 to 18 mm.diameter, filled for 10 mm. of its length with palladium asbestos, and it is found that the speed of the gas through such a capillary should not much exceed 10 C.C. per minute. The use of a palladium sol, together with a soluble picrate as an absorbent for hydrogen, as suggested by Paal and Hartmann (ANALYST, 1910, 35,139), gives ex- cellent results, but, as originally described, the method is rendered tedious by the persistent frothing of the liquid.Moreover, the absorptive capacity of the reagent falls off somewhat rapidly on storage, even in the dark. The froth is instantly destroyed by the introduction of 5 drops of alcohol through the capillary, but alcohol makes the reagent useless for further determinations.As the reagent is unaffectedINORGANIC ANALYSIS 519 by mercury, the most convenient procedure is to use but a small quantity of it confined over mercury. The author treats 0.3 grm. or less of Kalle’s colloidal pal- Iadium with 5 C.C. of water, and after twenty-four hours the palladium sol is mixed with 10 C.C.of a saturated solution of sodium picrate and charged into a mercury pipette. The quantity named has an absorptive capacity of about 455 C.C. of hydrogen, and can be depended on to absorb a quarter of that amount quantitatively and quickly from a gas mixture. Alcohol is used to destroy foam, and the contents of the pipette are then transferred to the palladium residue bottle, and the pipette is recharged after being washed free from traces of alcohol.G. C. J. Methods for the Estimation of Iodides. W. Sehirmer. ( A ~ c h . Pharnz., 1912, 250, 44$-451.)-The ferric chloride, nitrite, and iodate methods for the estimation of iodides were found to yield the most trustworthy results under the following conditions : Ferric Chloride Method-About 0.4 grm.of the iodide is dissolved in not more than 20 C.C. of water, and the mixture is treated with 5 grms. of ferric chloride solution ; after the lapse of one hour the mixture is diluted with 120 C.C. of water, 10 C.C. of phosphoric acid (25 per cent.) are-added, the liberated iodine is dissolved by the addition of 0.5 grm. of potassium iodide, and titrated with thiosulphate solution.One C.C. of Tc thiosulphate corresponds with 0.0166 grm. of potassium iodide. Nitrite Method-In a stoppered flask 0.5 grm. of the iodide is treated with 50 C.C. of water, 10 C.C. of dilute sulphuric acid, and 10 C.C. of a 1 per cent. sodium nitrite solution. At the end of two minutes, 1 grm. of urea is added, the contents of the flask are shaken for five minutes, and, after the separated iodine has been dissolved by the addition of 0.5 grm.of potassium iodide, the solution is titrated with thio- sulphate solution. Iodate Method.-Twenty C.C. of a 1 per cent. potassium iodate solution, 5 C.C. of dilute sulphuric acid, and 50 C.C. of water are placed in a stoppered flask, and 0-4 grm. of the iodide, dissolved in 10 C.C.of water, are introduced. After the lapse of about two minutes 5 grms. of borax are added, and at the end of a further five minutes the liberated iodine is dissolved by the addition of about 1 grm. of potassium iodide, and titrated with thiosulphate solution. w. P. s. Applications of the Method of Precipitating Metals as Iodides, etc., from Sulphuric Aeid Solution.G. Bressanin. (Gaxz. Chim. Ital., 1912, 42, Estimation of Tin.-Solutions of tin in sulphuric acid (sp. gr. 1.52) yield a, precipitate on treatment with potassium iodide in an analogous manner to arsenic and antimony (ANALYST, 1912, 206). The reaction, which is given by both stannous and stannic salts, is much more sensitive than the reaction of stannous salts with mercuric chloride.The tin precipitate is bright yellow, and resembles arsenic iodide, but is readily soluble in hydrochloric acid, whereas arsenic iodide is practically insoluble. It differs from antimony iodide in colour, and in being more soluble in hydrochloric acid. In order to obtain quantitative results it is necessary that the tin should be in the higher form of oxidation, since, unlike arsenic and antimony, 97-101.)-520 ABSTRACTS OF CHEMICAL PAPERS which are precipitated as iodides, stannic compounds are precipitated as stannic iodate, whilst stannous precipitates are unstable and undergo continuous oxidation.With this precaution of preliminary oxidation of the tin, arsenic and antimony may be estimated in the presence of that metal. The stannic precipitate, when dissolved in dilute tartaric acid solution, gives a solution which, when neutralised with sodium bicarbonates, does not absorb iodine.Estimation of Arsenic in Commercial Copper.-The proportion of arsenic in commercial copper is so small that a large amount of the copper is required for the estimation ; and since the copper salts on treatment with potassium iodide liberate an atom of iodine for each atom of copper, the total quantity of iodine thus set free is so great that it cannot be eliminated by a, single washing with a, solution of potassium iodide in sulphuric acid.The process must therefore be modified as follows : The finely divided copper (0-5 grm.) is dissolved in 5 C.C. of aqua regia, the solution evaporated to dryness, and the residue, after removal of all nitric acid, dissolved in about 250 C.C. of hot sulphuric acid (sp.gr. 1.52). On cooling the solution, and adding 25 C.C. of a 30 per cent. solution of potassium iodide, the copper and arsenic are precipitated together as iodides. The precipitate is allowed to stand for about twenty minutes, after which it is collected on an asbestos filter, and washed with the aid of a filter pump with 30 to 40 C.C.of sulphuric acid containing 5 per cent. of 30 per cent. potassium iodide solution, and the arsenic iodide dissolved off the filter by means of a dilute solution of sulphurous acid, whichalso reduces the remaining iodine. If the filter bed is sufficiently close none of the copper iodide will pass into the filtrate, which should remain perfectly limpid.The filtrate and washings are treated with sufficient iodine solution to give a, distinct blue coloration with starch paste, then rendered alkaline with sodium bicarbonate, and the titration completed with iodine solution. The arsenic is calculated from the amount of iodine used in this second period of the titration. C. A. M. Colorimetric Determination of Iron in Lead and its Oxides.J. A. Schaeffer. (J. Ind. and Eng. Chem., 1912, 4, 659-660.)-The method is substantially that of Thomson ( J . Chem. Soc., 1885, 47, 493), with the difference that greater care is taken to secure similarity in the solution8 to be compared. In the analysis of litharge or metallic lead, I grm. of the sample is covered with 15 C.C. of water, and enough nitric acid is added to convert all the lead to nitrate.The solution is diluted if basic nitrate separates, is boiled for several minutes to peroxidise iron, and is then neutralised with ammonia, and again rendered faintly acid by addition of a measured amount of dilute nitric acid. It is then transferred to a 100 C.C. Nessler glass, 15 C.C. of thiocyanate (5 per cent.) is added, and the mixture diluted to the mark, and its colour matched by adding a standard solution of ferric ammonium sulphate from a burette to a cylinder containing 15 C.C.of thiocyanate and as much nitric acid as was added to the test solution after neutralisation. In the analysis of red lead, the initial treatment is the same, but when the solvent action of the nitric acid slackens, 10 C.C. of hydrogen peroxide (2 : 7) is added, and the solution boiled for one minute.The solution is neutralised, acidified again by addition of a measured quantity of dilute nitric acid, and cleared, ifINORGANIC ANALYSIS 521 necessary, by addition of a few drops of hydrogen peroxide solution. To the corn- parison cylinder 10 C.C. of hydrogen peroxide solution (2 : 7) as well as a measured quantity of nitric acid and thiocyanate are added.Quantities of iron up to 0.03 per cent. can be estimated with an error not exceeding 0.001 per cent., and the small per- centage of copper present in lead and its oxides, such as are used in the manufacture of accumulators and high-grade lead-glass, does not interfere. G. C. J. Determination of Carbon in Steel by Direct Combustion in the Newest Form of Shimer Crucible, with the Aid of a Perforated Clay Dise.F. 0. Kichline. (J. Ind. and Eng. Chem., 1912, 4, 683-684.)- Descrip- tion of improvements in the platinum crucible with water-cooled brass stopper previously described by P. W. Shimer, and of modifications in the manner of using it for carbon determinations. The cru- cible is now made of slightly larger diameter, so as to accom- modate a No.00 Berlin crucible (-J bw$.-.;%!...;,&A 0 CROSS 6ECTION 70P BOTTOM CLAY DISC. instead of a No. 000. This allows the use of 2.72'7 grms. of drilliogs (1 mgrm. CO, then =0.01 per cent. C.), instead of only half this charge. The drillings are placed on a bed of sand, of which enough is taken to half fill the crucible, and are now covered by a perforated disc, like that shown in the illustra- tion, instead of with asbestos as formerly.Allowing for these modifications, the improved apparatus is used in the manner already described. The discs are best made of China clay, which is mixed with water to the proper consistency, moulded into shape, carefully dried, fired and annealed, With a little practice they can be constructed i n any ordinary laboratory, and with care in use will last for 100 deter- minations like the porcelaiu liners.Compared with asbestos they save time and are cleaner in working. G. C. J. Technical Analysis of Spelter, E. J. Ericson. (Eighth Inter. Cong. App. Chem., 1912, Vol. I, 183-186.)-The spelter (20 grms.) is covered with 100 C.C. water and 50 C.C. dilute (1 : 3) sulphuric acid, and allowed to stand overnight.The lead, cadmium, and undissolved zinc are then filtered off, washed with hot water, returned to the beaker, and dissolved in 10 C.C. of nitric acid. The solution is boiled until brown fumes cease to be evolved, and is then diluted and filtered from any trace of tin or antimony oxide. If these are absent, as is usually the case, the solution is diluted to at least 100 c.c., and 30 C.C.of ammonia and 5 to 10 grms. ammonium persulphate are added, and the solution boiled for five minutes. After ten minutes, the lead peroxide is filtered off on a double filter (11 cm.) and washed four times with hot 10 per cent. ammonia and five times with hot water. The precipitate is washed back into the beaker and treated with a, measured volume of hydrogen peroxide solution of known strength until dissolved.After addition of 15 C.C. of dilute nitric acid (sp. gr. 1.2) and 75 to 100 C.C. water, the excess of hydrogen peroxide is determined522 ABSTRACTS OF CHEMlCAL PAPERS by titration with permanganate. If 1 C.C. of the perinanganate corresponds to 1 mgrm. of iron, it should theoretically correspond to 1.85 mgrm.of lead; but experience shows that the factor 1-92 should be employed. Using this factor, i;he results check well with results obtained by the gravimetric chromate method, and the method is recommended for spelter containing 1 per cent. or less lead. The ammoniacal filtrate from the lead peroxide is boiled until nearly neutral and a white precipitate appears.About 40 C.C. of dilute (1 : 3) sulphuric acid is then added, and boiling continued for ten minutes. After diluting to 200 c.c., the solution is saturated with hydrogen sulphide, with occasional additions of water. The pre- cipitate is collected on a double filter, washed a, few times, and then redissolved on the filter with the least possible quantity of hot dilute hydrochloric acid.Any copper which may be present remains on the filter as sulphide, and may be ignited and weighed as oxide. The solution of cadmium (and zincj chloride is nearly neutralised with ammonia, and about 8 grms. of trichloracetic acid (cf. Fox, J. Clzem. Soc., 1907, 91, 964) dissolved in water is added-or more, if more is necessary-to dissolve the cadmium sulphide which separates on neutralisation.The solution is diluted to 200 c.c., and the cadmium reprecipitated by hydrogen sulphide. The cadmium sulphide is filtered off, and finally converted into sulphate or phosphate. G. C. J. Determination of Manganese by the Bismuthate Method. W. Blum. (Biyhth Inter. Cony. App. Chem., 1912, Vol. I, 61-85.)-As the result of exhaustive research in the U.S. Bureau of Standards, the conclusion is reached that the bismuthate method is more accurate than any other, even for the analysis of Bigh- grade manganese ores.I t is shown that the manganese value of permaoganate solution is identical, whether calculated from a sodium oxalate titration by means of the theoretical factor 0.1640, or determined by means of pure anhydrous manganese sulphate.Statements to the contrary (e.g., that of Brinton, ANALYST, 1911, 36, 305; see also Hillebrand and Blum, ibid., 1911, 36, 430) are probably due to the difficulty of depriving manganese sulphate of traces of free sulphuric acid without at the same time decomposing some of the manganese sulphate. I t is shown that prolonged heating to at least 440" C. is necessary to eliminate free sulphuric acid, whilst at temperatures above 525" C.there is risk of decomposition. The sodiiim oxalate method of standardisation is therefore recommended. 2% permanganate, which should be used in the analysis of high grade manganese ores, is standardised by dissolving as much sodium oxalate as will require nearly 50 C.C. in 250 C.C. of water containing 5 C.C. of sulphuric acid, warming to 80" to 90" C., and titrating slowly, The final temperature should not be below 60" C.gG permanganate, such as is used for determining manganese in steel, is standardised in a similar manner, but a sharper end-point is obtained by restricting the initial volume to about 75 C.C. Analyses are conducted as follows : To the cold manganese solution containing 20 to 40 per cent.of nitric acid (free from nitrous acid) in a bulk of 50 to 150 c.c., a slight excess of bismuthate (0.5 to 1 grm.) is added, and the mixture agitated for half a minute. The sides of the flask are washed down with 50 C.C. of 3 per cent. nitric acid, and the solution is filtered at once through asbestos, previously coatedINORGANIC ANALYSIS 523 with bismuthate. About 100 C.C.of 3 per cent. nitric acid is used to wash the flask and filter. A measured amount of standard ferrous sulphate solution is added, and the excess titrated with permanganate. For quantities of manganese up to 0-05 grm. the method is accurate to 1 in 500. The experience of the Bureau shows that no other known method, gravimetric or volumetric, gives results for which a higher degree of accuracy can be claimed.With quantities of manganese as large as 0.1 grm., the method as described gives rise to errors of several units per cent. I t is shown that permanganate solutions preserve their strength when exposed to diffused light, if protectedifrom reducing substances, and that i ! solutions of ferrous sulphate are as stable as those of ferrous ammonium sulphate, the rate of oxidation under average conditions being about 1 per cent.in five days (see also Baskerville and Stevenson, ANALYST, 1911, 36, 467). G. C. J. Rational Analysis of Nitrate of Soda. W. S. Allen. (Ezghih Inter. Colzg. App. Chem., 1912, Vol. I, 19-31.) - A protest is raised against tbe custom of estimating the content of sodium nitrate in commercial nitrate of soda by subtracting from 100 per cent.the sum of the water, insoluble matter, and chloride and sulphate expressed as sodium chloride and sulphate. The method invariably overestimates the sodium nitrate, the average error being about 1 per cent.; but it may reach 3 per cent. Not only do all samples contain soluble salts of calcium, magnesium, iron, and aluminium in small amount, but sodium perchlorate is occasionally present up to nearly 1 per cent., and the percentage of potassiuni nitrate may exceed 8 per cent.Though commercial nitrate of potash is more valuable than the sodium salt, its presence in admixture with the latter is a disadvantage to the nitric acid maker, as its nitrogen content is lower than that of nitrate of soda. It is held that the basis of sales should be the nitrate content as determined by a direct method.A modifi- cation of the Devarda method (Zeitsch. anal. Chem., 1894, 33, 113) is described, and the opinion expressed that it will be found simpler than the use of the nitrometer by those who are not thoroughly familiar with the use of that instrument. The new method consists in reducing the nitrate to ammonia in alkaline solution by ineans of Devarda metal, and driving the ammonia over into a measured volume of standard acid by means of a current of air, which bubbles through tho reduced solution con- tained in a flask which is heated in a water-bath.Between the flask and the receiver is a spray-tap, consisting of four 1-inch bulbs blown on a tube about 8 inches long. The bulbs are filled with glass-wool, and drain back towards the reduction-flask.To prevent undue condensation in this spray-trap, and to hasten the distillation of the ammonia, the bulbed tube is surrounded with a lead jacket through which steam is passed. The air which is drawn through the apparatus is previously freed from carbon dioxide, and methyl red is preferred as indicator. G. C. J. Effeet of Ignition on the Solubility of Soil Phosphates. C.B. Lipman. (J. Id. and Eng. Chem., 1912, 4, 663 664.)-Fraps (ANALYST, 1911, 36, 371) showed that the ignition of phosphate minerals such as wavellite, dufrenite, etc., for ten minutes at a low red heat increaaed about ten times the solubility of the phosphoric acid in them in nitric acid, and rendered it almost entirely soluble in 12 per cent.524 BBSTHACTS OF CHEMICAL PAPERS hydrochloric acid.The author has frequently noticed the reverse effect when soils were ignited, and below are recorded the figures obtainable when the phosphoric acid is estimated in soils of varying composition before and after ignition : Percentages of P,O,. . 1. 2 . 3. 4. 6 . Ignited ... 0.410 0.150 0.090 0.167 0.151 N-ot ignited ...0.460 0.250 0.130 0.191 0.190 Theoretical considerations are discussed as to the possible causes of the loss noticed and the reason for the reverse effect mentioned above. H. F. E. H. Action of Dimethyl-Glyoxime on Platinum Salts. M. Wunder and V. Thuringer. (Ann. Chinz. anal., 1912, 17, 328-329.)-Platinum salts form an insoluble compmnd with dimethyl-glyoxime, but with much more difficulty and at a higher temperature than the corresponding palladium compound (ANALYST, 1912, 379).The platinum precipitate is brown, blue, or greenish-blue while moist, but assumes a bronze colour when dry. I n experiments to render the reaction quantitative the precipitate, obtained in the same manner as with palladium (Zoc. cit.), was digested for several hours on the water-bath, then separated, dried.and ignited. From 0.0292 grm. of platinum there was obtained 0.0222 grm. Better results (e.g., 0.266 grm.) were obtained by the use of an alcoholic solution of dimethyl- glyoxime, while by adding sodium citrate to augment the reducing action the figures were still better (e.g., 0.0250 grni. from 0.0262 grm.). For each part of platinum one and a half parts of the reagent were used.The presence of ammonium chloride am~lerated the formation of the precipitate, but did not lead to better results than those quoted. C. A. M. Rare Earth Reactions in Non-Aqueous Solvents. 0. L. Barnebey. (J. Amer. Chem. Soc., 1912, 34, 1174-1189.)-A study of the reactions of the common acids and bases with the yttrium group-neodymium, lanthanum, and cerium-using acetone as solvent.The reactions are of the same general order as those in aqueous solution, but the solubilities vary more widely. I n some cases compounds which are readily soluble in water have been found to be nearly insoluble in acetone, so that the use of acetone as solvent, in combination with reagents used for the separation of the earths by fractional precipitation, promises to make such separations sharper and less tedious.The basic nitrate scheme of fractionation, using acetone as solvent, is very effective as a means of separating ceria from the other earths, but none of the other separations described are separations in the sense in which the term is usually understood by analysts. A separation of the yttrium group, using tartaric acid as precipitant, has been found very effective for fractional purposes.The serial order established is ytterbium (lutetium and neoytterbium), holmium, erbium, dysprosium, yttrium. Other separations described depend on the use of alkaloids as fractional precipitants in acetone solution. G. C. J. Exact Determination of Sulphur in Pyrites. W. S. Allen and H. B. Bishop.(Eighth Inter. Cong. App. Chenz., 1912, Vol. I, 33-51.)-The method dependsINORGANIC ANALY S1S 525 on oxidation and solution by means of a solution of bromine in carbon tetrachloride followed by nitric acid, reduction of ferric iron by means of aluminium powder, and precipitation in cold dilute solution by slow addition of barium chloride solution. Large quantities are taken for analysis, so that the barium sulphate to be weighed approximates 5 grms.Under the prescribed conditions, the barium sulphate always contains barium chloride, but the amount of this is very nearly constant (0.0137 to 0-0150 grm.), and the results show that the error due to this cause is almost exactly compensated by the solubility of the barium sulphate. The sample is not ground more finely than 80 mesh (C'.Allen and Johnston, ANALYST, 1910, 35, 332), and 1.3736 grms. is weighed out into a 300 C.C. beaker and covered with 10 C.C. of a mixture of 2 volumes bromine and 3 volumes carbon tetra- chloride. Bromine alone is too violent, and its aqueous solution too weak. The mixture is shaken from time to time, and after fifteen minutes 15 C.C. of nitric acid is added, and the mixture left for a further fifteen minutes at room temperature, with occasional shaking.The beaker is then placed on an asbestos board on the steam-bath until all action has ceased and most of the bromine has volatilised. The clock glass covering the beaker is next raised somewhat by means of glass riders, and the contents of the beaker are evaporated to dryness by immersing it in the steam-bath up to its rim.Hydrochloric acid (10 c.c.) is added, and the solution again evaporated to dryness, and the residue dried for several hours at 100" C. to render silica insoluble. The residue is moistened with 4 C.C. of hydrochloric acid, and after five minutes 100 C.C. of hot water is added, and the mixture boiled for five minutes. It, is allowed to cool for about five minutes, and then 0.2 to 0-3 grm. of aluminium powder is added, and the contents of the beaker agitated until the colour of ferric iron disappears. The solution is cooled to arrest the action of acid on aluminium, which might otherwise give rise to mechanical loss on the filter, and is filtered through a 12.5 cm. filter, which is washed nine times. The filtrate is diluted to about 1,600 c.c., and a further 6 C.C. of hydrochloric acid is added to it. About 125 C.C. of 5 per cent. barium chloride solution is added without stirring, and at a, rate not exceeding 5 C.C. per minute. The paper includes description of an appliance for effecting this without attention. When all the barium chloride has run in, the contents of the beaker are stirred, and then allowed to stand for not less than two hours. The liquid is decanted through a 35 C.C. Gooch filter with a moderately thick asbestos mat, and the precipitate is transferred to the filter and washed six times with cold water. The crucible is then dried and heated for half an hour with the full flame of a Bunsen burner (or in an electric oven at 870" C.). The weight of the precipitate multiplied by ten gives the percentage of sulphur in the sample. Test analyses show that the method gives results of the accuracy stated, and that it is unaffected by the presence of such amounts of lead, copper, zinc, arsenic, lime, and silica, as may occur in pyrites. The results are accurate to within 0.05 per cent. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9123700516

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年代:1912

数据来源: RSC

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526 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Crystallo-Chemieal Analysis : A New Method of Chemical Analysis. G. von Fedorow. (Zeitsch. f. Krystallogr., 1912, 50,513-575; through NatzLre, 1912, 89,503- 505.)-It is shown that there is a correct mode of setting up a crystal for descriptive purposes, and that this setting is arrived at independently of external “ habit,” being based on calculations of the “ reticular density ” (closeness of packing of the nodes, or ‘6 points,” of the space-lattice or point system) along the planes of the principal faces.The setting which corresponds to primary faces of maximum reticular density is the only correct one on which comparisons should be made. A table including 10,000 crystalline substances, which have been goniometrically measured, has been prepared, arranged in regular progressive order, and calculated on the above lines as regards correct setting.If a few measurable crystals of any one of these substances be subjected to a sbort goniometrical investigation, occupying at most a few hours, and often only a few minutes, the substance of which the crystal is composed can then be identified by reference to the table.In short, provided a chemical substance has Once had its crystals measured, it is possible to detect it at any time by merely making a few brief measurements so as to be able to calculate the elements-by a shortened process, partly graphical, which the author has perfected-and then searching the table for the substance therein recorded as possessing such constants.A number of test cases have been sent to the author, and he succeeded in identifying them correctly. The method has the advantage of not injuring the crystals, but fails in its simple form with cubic crystals, in which the angles are always the same ; but a determination of refractive index is successful where that of symmetry, elements, and angles fail. H. F. E. H. Luminescence Analysis.0. Wolff. (Chem. Zeit., 1912,36,1039.)-Lehmann has devised a fluorescence microscope which is used with ultra-violet light and has a screen for the protection of the eye. By means of this instrument the author has found that the red fluorescent particles in crude potashes consist of potassium sulphide, whilst the particles showing a blue fluorescence consist of organic matter, mainly in combination with the mineral matter.I n like manner the orange fluorescence of mercuric chloride is shown to be due to particles of mercurous chloride. Chemically pure mercuric chloride shows no fluorescence, but in many of the preparations on the market traces of calomel may thus be detected, although they escape detection by chemical means. Resublitnation of pure mercuric chloride in a tube causes the orange fluorescence to appear, owing to the formation of traces of calomel. Another direction in which this microscope has proved useful is in the examination of anthracene, which when pure shows a blue fluorescence, but when impure fluoresces green, owing to the presence of a substance with a yellow fluorescence.The fluorescence of the latter disappears on heating.C. A. M. New Type of Inorganic Filter for Laboratory Purposes. M. A. William- son and P. A. Boeck. (J. Ind. and Eng. Chem., 1912,4,672-677.)-The material ofAPPARATUS, ETC. 527 the new filter is ‘‘ alundum ” (cf. Boeck, ANALYST, 1912, ass), a porous ware already in use for the construction of extraction thimbles and filter plates (ANALYST, 1912, 109).When given the form of an ordinary crucible, this ware was not successful in replacing the Gooch crucible with asbestos mat, because the upper portion of the crucible absorbed strong saline solutions, and the time required to wash the salt out from those portions of the crucible above the level where the suction was operative was so great as to outweigh any advantages the crucible might otherwise have possessed.Filtering-cones have now been constructed which overcome this difficulty, and which serve as combined filter and crucible. The use of the cone ag filter is shown in Fig. 1. A funnel a little larger than the cone is equipped with a piece of soft rubber tubing about 14 inches long and 1& inches in diameter (the cones are 1s inches in diameter and la inches high), and the cone finds a FIG.1. PIG. 2. seating on the moistened rubber. The filter and any precipitate it may contain can be washed perfectly in two or three minutes, and, after drying, can be ignited. The material is unaffected by sulphuric, nitric, or hydrochloric acid. I t is somewhat hygroscopic, a cone of the dimensions given picking up about 1 mgrm.on exposure to the air of the laboratory for one hour, but there is no further gain in weight in three hours. Among the test numbers given, those for barium sulphate are all low- from 0.1329 to 0.1331 found against 0.1349 required by theory and found by ordinary filtration using t% paper. Since parallel experiments in which a paper was placed inside the cones also gave 0.1330, the low results appear to be due not to penetration of the filter by the finely divided precipitate, but to the solubility of the precipitate in the washing water, of which there is a tendency to use large quantities when a filter operates very quickly.Fig. 2 shows how these cones may be freed from any soluble salts suspected to lie within their pores. The illustration actually figures a crucible-shaped filter, of the type which was abandoned owing to its tendency to absorb salts ; but a similar arrangement serves t o clean a cone, as to the cleanliness of which there may be a doubt.The cones are made by the Norton Company, Worcester, Mass., U.S.A. G. C. J.528 ABSTRACTS OF CHEMICAL PAPERS Apparatus for Rapid Distillation of Mercury in Vacuo. L. Dunoyer.(Compt. rend., 1912, 154, 1344-1346.)-The apparatus consists of a bent glass baro- J meter tube, A B, of 4 to 5 cm. diameter and 35 to 40 cm. high. The limb A terminates in a tube about 10 mm. in diameter, which dips into a small beaker, C, fixed to the tube. This beaker hangs in a tube, G, which is cemented into the bottom of the rectangular glass dish E, which can accommodate some 20 kgrms.of mercury. The end B of the barometer-tube terminates in a tube about 120 cm. long and not more than 3 mm. in diameter. This narrow tube dips into the vessel D, which is provided with a side outlet, and is itself contained within the bottle F. The bottle F is evacuated by connecting the cock S to a water-pump. This causes the mercury to rise to the level shown in A , and the circuit is then completed through the electrical heating device, and the distillation com- menced. The use of the vessels C and D make it possible to clean or empty F without interrupting the distillation.The heating device consists of a winding of chrome-nickel wire, extending from the constriction of the tube A to the highest point of the bend, separated from the glass by insulating material and externally covered with a thick layer of some poor conductor of heat.I t is to be noted that only the small portion of mercury in A and the vapour above it are heated by the current, the bulk of the mercury in E remaining cool until drawn up into A to replace mercury which has evaporated. The apparatus possesses a simple device for breaking the eleotrical circuit if, and when, the supply of mercury in E is exhausted or rednced to some assigned level.From the base of the vessel Hproceeds a narrow S-tube, the other end of which dips into the mercury in E. His closed by a wooden plug through which is screwed an electrode, LW, of amalgamated copper tube. The height of this electrode is adjusted until its lower end corresponds to the level at which it is wished to arrest the further depletion of the mercury in E.Mercury is then poured into H, covered with a layer of petroleum, and the plug carrying the electrode is pushed into H, whilst closing the upper end of the tubular electrode with the thumb or a stopper. In this way mercury is forced into the S-bend, thus establishing electrical connection between the electrode and the mercury in E.The current passes from the terminal I through the electrode M and the mercury in B, the S-bend and E, and thence by the nickel wire L, which dips into the mercury in E, to the heating coil, the other terminal of which is at J. When the level of the mercury in E has sunk to the level of the lower end of the electrode A!, the electrical circuit is automatically broken and the distillation is suspended.G. C. J. Two New Pieces of Laboratory Apparatus. E. Berlin. (Zentralbl. fiir Physiol., 1912, 26, 219; through Chern. Zentmlbl., 1912, 11, 889.)-The first apparatus is for the evolution of hydrochloric acid gas from its aqueous solution by the action of sulphuric acid. I t consists of a round-bottomed flask, into the closedAPPARATUS, ETC.539 top of the neck of which are sealed two tubes, each terminating downward somewhat below the base of the neck inside the flask, and leading upward, through a stopcock, to a bulb carrying a funnel and a tube opening to the air; funnel and tube are simultaneously opened and closed by the plug of a stopcock passing through both. A delivery tube, and an emptying tube reaching the bottom of the main flask, are sealed into the neck halfway up, and are closed with stopcocks.The bulbs are charged with concentrated hydrochloric acid and concentrated sulphuric acid respectively. The second apparatus is for the continuous extraction of a liquid, such as water, by a heavier liquid, such as chloroform. Into the neck of a round-bottomed flask with reflux condenfier is sealed a tube with its mouth, directed downwards, a short distance below the cork.This tube passes down outside the neck to join a second tube, sealed through the base of the neck, and reaching the bottom of the flask. From the junction the tube is widened, and passes diagonally downwards to a smaller flask in which chloroform is boiled. Chloroform is placed in the larger flask until the mouth of the tube reaching to the bottom is well covered, and on this sufficient of the aqueous liquid to be extracted to cause the chloroform to overflow into the smaller flask.Chloroform, as vapour, passes up the side tube, is condensed, sinks in drops through the aqueous liquid, and flows over into the smaller flask. 0. E. M. Apparatus for the Estimation of Adulterants in Vegetable Powders, and Notes on Starch Granules.C. Hartwich and A. Wichmann. (Arch. Pharm., 1912, 250, 452-471.)-The apparatus consists of a microscope slide on which is engraved a square, the sides of which measure 1.5 cm. ; this square is divided into 100 equal squares, and around its edges are placed strips of cover-glass, SO that a shallow cell, 0.25 mm.in depth, is formed, The powder under examination is diluted with a known quantity of sugar, say in the proportion of 1 to 100 or 1 to 1,000, and a small quantity of the mixture is weighed out into the cell. For instance, if 0.05 grm. of the mixture (1 to 100) be taken, the cell will contain 0*0005 grm. of the original powder. A drop or so of water is then added to the cell, and, when the sugar has dissolved, a cover-glass is placed over the whole, and the slide is examined under the microscope, the foreign particles being counted. The apparatus is particularly suitable for estimating the amount of clove-stalks in pow- dered cloves, sandal-wood in saffron powder, starches in powders, etc. The author has also determined the weight of various starch grains by means of the apparatus, the weight of a single grain, after the starch had been dried at 100" C., being: Oryza sativa, 0~0000000000163 grm. ; Zea Mais, 0*0000000007%9 grm. ; Maranta arzcndinacea, 0~0000000063 grm. ; Triticzhm sativum, 0~0000000000605 grm . ; Canna edulis, 0°0000000502 grm. ; Solanurn tuberosum, 0~00000000644 grm. The specific gravities of the dry starches were found to be : Canna edzdis, 1.5255; Solanurn tzlberosum, 1.5247 ; Maranta arundinacea, 1.5215 ; Oryxa sativa, 1.5134 ; Zea Mais, 1.4809 ; Triticzwz sativunt, 1.4696. w. P. s,

ISSN:0003-2654    

DOI:10.1039/AN9123700526

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年代:1912

数据来源: RSC

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530 REPORT REPORT. Report of the Government Chemist upon the Work of the Government Laboratory for the Year ending March 31, 1912, with Appendices. (Issued as a Parliamentary Paper, pp. 1-27.)-The Beport commences with a short recapitulation of the principal steps in the history of the Laboratory and its work, from the origin of the Laboratory in 1843 to the year 1911, when the Government Laboratory was separated from the Department of Customs and Excise, and constituted a new Department under the official title of the ‘‘ Department of the Government Chemist.” Changes in the method of staffing the Laboratory have also been made, and, whilst Revenue Officers still attend to that part of the work which pertains to the Revenue, chemists recruited from “ the open market ” are employed for non-Revenue work.The duties performed by the staff include analyses of samples taken by Revenue officers, of stores supplied to Government Departments, of dairy produce imported into this country, of samples referred by magistrates under the Food and Drugs Act, the Fertilisers and Feeding-Stuffs ,4cts, etc. The total number of analyses and examinations made in the two branches of the Laboratory during the year was 195,170, compared with 186,044 for the preceding year.Including samples examined in provincial stations, the total number was 345,181. For the purpose of checking dilution and adulteration 7,464 samples of beer were taken from retailers, and of this number 452 were found to have been diluted. None of the samples contained saccharine.Of 444 samples of herb beers and temperance beverages examined, 300 contained less than 2 per cent. of proof spirit ; 107 contained less than 3 per cent. ; 30 between 3 and 5 per cent.; 6 between 5 and 8 per cent.; and 1 sample 10.6 per cent. One thousand and forty-six samples of beer and brewing materials were examined for the presence of arsenic, but only 18 of these contained more than one-hundredth of a grain of arsenious oxide per gallon (or pound, in the case of solids). Of 122 samples of malt 5 exceeded the limit, the highest proportion found being one-fortieth of a grain per pound ; 8 samples of wort and beer contained excessive quantities of arsenic-the highest quantity being one-twentieth of a graiu per gallon.The highest quantity of arsenic found in 377 samples of other brewing materials was one-fiftieth of a grain per pound.In addition to the samples connected with brewing, 292 samples of mineral acids, chemicals, etc., were tested for arsenic. Attention is drawn to the fact that 19 samples sold as cider were found to be artificially prepared liquids, and to be free from apple - juice. A considerable proportion of the 56 samples of liqueur chocolates analysed waR found to contain from 6 to 12 per cent.of proof spirit, and in two cases the quantity reached 25.0 and 28-8 per cent. respectively. In connection with the Board of Agriculture and Fisheries, and the Department of Agriculture and Technical Instruction for Ireland, 3,228 samples were examined, including 70 samples of milk, 63 of condensed milk, 71 of cream, and 1,309 of butter.Only 11 of the samples of imported butter contained excessive quantities of water ; 396 contained boric preservative, and 180 added colouring matter. The samples of imported milk, meam, and butter are always tested for the presence of preservatives.REPORT 531 The whole milk imported in churns was usually free from preservatives, but 3 samples contained boric acid and 1 hydrogen peroxide.Boric acid is generally present in imported cream, and its use in past years has been supplemented by the addition of salicylic acid and hydrogen peroxide. During the present year no sample was found to contain salicylic acid, and in only a few cases had hydrogen peroxide been used. The presence of benzoic acid and fluorides was not detected in any of the butters-boric acid being the only preservative present.All the samples of cream and butter from Norway, Sweden, Russia, and Denmark, were free from preservatives. None of the samples of margarine examined contained more butter-fat than is legally permissible, and an excessive quantity of water was found in one case only. One hundred and forty samples of sheep-dips were received for examination : 20 were deficient in active ingredients, and in 63 other cases the formula required modification.Linseed sometimes contains small quantities of glucoside, which is capable, under certain conditions, of producing hydrocyanic acid, although it is stated that the hot-press process of preparing linseed cakes destroys the enzyme.Results of an investigation showed that, when allowance is made for the oil removed during the pressing, the cake yields the same amount of hydrocyanic acid as the original seed. Samples of oysters obtained from the West of England were examined in consequence of a suspicion that copper-poisoning had resulted from eating them. Many of the oysters had a distinct green appearance, and all contained copper and zinc, the largest amount of copper found being 1.22 grains of metallic copper per dozen oysters, and of zinc 2.31 grains.The oysters containing most copper were so distinctly green in colour that no person would have been likely to eat them. The growth of the oysters did not appear to have been affected by the presence of the two metals. Ninety-three samples referred by magistrates under the Food and Drugs Acts were examined during the year, I n 14 cases, including 9 samples of milk, the reports of the public analyst could not be confirmed.Certificates could not be issued with regard to 3 other samples of milk, owing to the high state of decom- position in the case of 2 of the samples, and because the bottle containing the other sample was burst in transit.The following are the particulars of some of the more important cases : Butter.-In one case where the charge was excess water, less than the legal amount was found. In 2 out of 3 samples alleged to contain foreign fat, the results obtained confirmed those of the public analyst; in the third case the butter gave results of an abnormal character, but having regard to the fact that similar results were obtained from the analysis of genuine butter from the same locality, it was impossible to say that the fat was not wholly butter-fat.One sample of butter, alleged to contain cocoanut oil and an excess of water, was found to contain excess of water, but no foreign fat. Milk.-Except in the case of 9 samples, the results obtained were in agreement wholly or partially with those of the public analyst ; the charge in three of these cases was added water and in the other six abstraction of fat.Mu2t Vinegur.-One sample contained a large proportion of vinegar not derived from malt or grain, but in the case of the other sample received the results were not inconsistent with those given by genuine malt vinegar.532 REPORT Whisky.-In 1 of the 2 samples received the alcoholic strength was found to be 21 degrees under proof, and was not therefore below the legal strength.Mar- garine.-The one sample received contained more than 10 per cent. of butter-fat. Rice.-The report of the public analyst, that the sample had been “faced,” was confirmed. Cream of Tartar.-A sample condemned by the public analyst was found t o comply substantially with the requirements of the British Pharmacopceia.The other samples referred consisted of rum, cream, and coffee, and in all these cases the results of the public analyst were confirmed. The total number of samples submitted by the Board of Agriculture under the Fertilisers and Feeding Stuffs Acts was 47, consisting of 15 fertilisers and 32 feeding stuffs.The particulars relating to some of these samples were as follows: Plant-Food. -An article, sold in penny packets, and guaranteed to contain 22 per cent. of phos- phates and 0.85 per cent. of potash, consisted mainly of fine earth and ashes with only 1.84 per cent. of phosphate and 0.33 per cent. of potash. Tomato Manwe.- Contained only 4.7 per cent.of potash available for plant-food, although stated to contain “4.6 per cent. of free potash and 12.4 per cent. of combined potash.” Fish Manure.-The sample examined consisted of fine ashes mixed with a, few fish-bones, and contained only 0.59 per cent. of nitrogen and 3.4 per cent. of phosphates. The other fertilisers examined included superphosphates, wool-waste, bone-meal, and guanos, deficient in phosphates, nitrogen, or potash. Cottonseed ilfeaE.-A sample described as “ Double Decorticated Cottonseed Meal ” consisted of the ground meal of undecorticated cottonseed cake, containing the whole of the cortex proper to the seed. Milling Products.-A sample of barley meal was found to contain 5 per cent. of sand. As much as 50 per cent. of ground-oat husks was present in a sample of “sharps.” Other samples contained various quantities of tapioca meal and rice husks. Details regarding the numbers of various articles examined are given in the Appendices to the Report. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700530

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年代:1912

数据来源: RSC

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532 REPORT STUDY COMMITTEE OF THE INTERNATIONAL DAIRY FEDERATION.::: LAKGE VOORHOUT 88, THE HAGUE, October, 1912. DEAR SIR,-& the final general meeting of the Fifth International Dairy Congress, held at Stockholm, July 1, 1911, the following resolutions were carried : “ The next International Dairy Congress will fix tbe percentage of butter-fat in the dry matter which may be considered as normal figures for all sorts of cheeses which are found in the markets of the world.” ‘‘ To secure the exactness of the result of the discussions, the Study Committee of the International Dairy Federation shall do the preparative work necessary specially to arrive at an international agreement on tha methods for the analysis of cheese.” At the meeting of the Study Committee, held at Brussels on March 13 and 14, 1912, I was invited to prepare reports for this purpose, and I now beg to submit for * Readers of the journal interested in this matter are invited t o cornmimicate with Dr.SwavingSTUDY COMMITTEE OF THE INTERNATIONAL DAIRY FEDERATION 533 your consideration proposals for the unification of tho methods for the analysis of cheese. These proposals are the consequence of discussions of a special committee com- posed of delegates of cheese control-stations, of the Government dairy-station at Leiden, of municipal laboratories, of the Government agricultural experimental stations, and of myself as chairman.This committee has agreed to the methods for the analyses of cheese to be followed in the Netherlands. I should feel obliged if you would kindly give these proposals your careful consideration, and let me know what modifications, if any, you wish to suggest.- Yours faithfully, SWAVING, Secretary of the Study Committee of the International Dairy Federation.PROPOSALS FOR THE UNIFICATION OF ANALYTICAL METHODS FOR CHEESE. 1. Determination of Water in Cheese.-Five grms. of cheese are weighed in a wide dish containing clean sand, and mixed and well ground up by means of a glass bar with flattened end, which has been weighed with the dish.The sample is then dried at the ordinary temperature-if possible in vacuo-for at least sixteen hours, and immediately after- wards dried for about one hour in an oven at 105' C., and weighed. Drying is continued, and weighing repeated with short intervals (half an hour). 2.Determination of Fat in Cheese-(a) By Gerber's Hethod, with Modified Cheese Butyro- meter (Van Gulik) for Three Grms. of Cheese.- Three grms. of cheese are introduced with the aid of a funnel into the widened part of the cheese butyrometer, which has been previously half filled with sulphuric acid (sp. gr. 1.50). The weighing of very soft cheese is made in a small beaker.The butyrometer is then warmed in a water-bath at 65" to 70" C., and the casein dissolved, while shaking and swinging the buty- rometer at intervals. When no more small particles of cheese are visible, the butyrometer is left in the water-bath for a short time, while swinging at intervals, and, after 1 C.C. amyl- alcohol has been added, it is filled with sulphuric acid up nearly to the division mark 35.The - contents are mixed with care, not swinging the FIG. 1 (4 size). - butyrometer oftener than necessary for a corn- GERBEIL- VAN Gu- LIK BUTYROMETEI:. plete mixing, then left for about five minutes in FIG. 2 (& size).- SMETHAM FLASK.534 STUDY COMMITTEE OF THE INTERNATIONAL DAIRY FEDERATION the water-bath, and centrifuged for four minutes at a speed of 1,000 revolutions per minute.The diameter of the disc-plate of the Gerber centrifugal machine must be at least 47 crns. (the machine should be warmed when the temperature of the room is low). Finally, the butyrometer is placed for five minutes in a water-bath at 65" C., and the height of the fatty layer read at 65" C. ( b ) By the Hydrochloric Acid Method.':'-One to 5 grms.of rasped cheese are gently boiled with 20 C.C. hydrochloric acid (sp. gr. 1.13) in a small flask, and shaking until all small particles have disappeared ; then either Smetham's perforation method or Schmidt -Bondzynski's modified method is applied. Smetham's Perforation Method.-The hydrochloric acid solution, when cool, is carefully introduced into the flask of Smetham's extractor, as modified for the estimation of fat in milk (Marius, Utrecht), and the flask filled with ether until it flows over.After two hours the ether is evaporated, and the fat dried for half an hour in the oven at 102" C. For control, a second flask can be connected to the extractor and treated as above. Modijed ~chmidt-Boizdxynski's Method. - The hydrochloric acid solution is carefully introduced into a mixing cylinder of 100 C.C.capacity, and, when cool, ether is added till the total volume is about 50 C.C. The cylinder is closed with a damped cork, then well shaken, and left for at least two hours to separate. The ether-fat solution is then drawn off as completely as possible (to at least 1 c.c.) in a weighed flask. A fresh quantity of 50 C.C. ether is introduced into the cylinder, and the contents swung several times. After one hour's rest the ether is again drawn off as completely as possible and added to the first ether-fat solution in the weighed flask. The ether is then distilled off, and the fat dried for half an hour in the oven at 102' C. Drying is continued to constant weight. Drying is continued to constant weight.

ISSN:0003-2654    

DOI:10.1039/AN9123700532

出版商:RSC    

年代:1912

数据来源: RSC