摘要:

FEBRUARY, 1912. Vol. XXXVII., No. 431. THE ANALYST. ~~ ~ ~~ OBITUARY. WE deeply regret to have to record the death of one of the Founders and Past Presidents of the Society of Public Analysts, Dr. John Muter. H e died on December 11, 1911, at Worthing. An obituary notice will appear in the next number of this Journal. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE ESTIMATION OF FURFURAL BY MEANS OF FEHLING’S SOLUTION.” BY LEWIS EYNON, B.Sc., F.I.C., AND J. HENRY LANE, B.Sc., F.I.C. (Read at the Meeting, December 6, 1911.) ACCORDING to J. T. Flohil, under certain conditions Fehling’s solution is reduced by furfural in direct proportion to the quantity of the latter, and he has proposed a, method for the determination of pentosans in which, after distilling the material with acid, the furfural in the distillate is determined by means of Fehling’s solution (Chem.Weekblad., 1910, 7, 1057; ANALYST, 1911, 36, 161). The method is conducted as follows : Fifty C.C. of the acid distillate (the total quantity of which amounts to 400 c.c.) are neutralised, treated with 20 C.C. of Fehling’s solution, and made up to 100 c.c., the whole being boiled for thirty-five minutes under a reflux Liebig’s condenser. In order to avoid any loss of furfural, a few pieces of ice are placed in the upper end of the condenser-tube, which is funnel-shaped. A blank determination must be made in which the same quantity of sodium chloride is present. Flohil finds that under these conditions the furfural-copper ratio is 0.3775 : 1-Le., that 1 molecule of furfural is equivalent to 4 atoms of copper or 2 atoms of oxygen.The amount of cuprous oxide may be found, not only by direct weighing, but indirectly by the iodometric determination of the unreduced copper (Schoorl, 2. Angew. Chem., 1899, 12, 633). We have carried out series of experiments to ascertain the influence of varia- tions in the concentrations both of furfural and of sodium chloride, and to determine * This work was carried out in accordance with the terms of the Analytical Investigation Scheme,42 EYNON AND LANE: THE ESTIMATION OF FIJRFURAL Weight of Sodium Chloride : Grms. the degree of accuracy that can be attained by Flohil’s method. We find that, in heating the furfural solution with Fehling’s solution under an ordinary Liebig’s condenser, the use of ice to insure the complete condensation of the furfural is quite unnecessary.Contrary to Flohil’s statement, we find that the copper-reducing power of furfural is not independent of the concentration, the furfural-copper ratio ranging from 0.376 to 0.450, as the amount of furfural present is increased from 0.01 to 0.05 grm. There appears to be no ground for Flohil’s assumption of a, simple stochiometric relation between the furfural and the copper. The furfural employed was purified by distillation in steam ; it was then dried over calcium chloride and redistilled. We have found that the reducing power of dilute aqueous solutions of furfural undergoes no change in the course of several weeks. The Fehling’s solution used was prepared by mixing equal volumes of a solution of 69-26 grms.of crystallised copper sulphate per litre, and a solution containing 100 grms. of sodium hydroxide and 348 grms. of Rochelle salt per litre. Method of Procedure.-A solution containing not more than 0.05 grm. of furfural was mixed with 20 C.C. of Fehling’s solution and a known quantity of a salt solution in a flask of about 200 C.C. capacity, the whole being made up to 100 C.C. with water. The flask was fitted with a, vertical reflux condenser, and heated on an asbestos card over a flame of such size that the liquid was brought to the boiling-point in twelve to fifteen minutes, after which it was kept boiling for exactly thirty-five minutes. The precipitate of cuprous oxide was then collected in a Soxhlet tube, washed with water and alcohol, dried a t 110” to 115” C .and weighed, after which it was reduced to copper and weighed again. Table I. gives the results of a number of blank determinations in which mixtures of 20 C.C. of Fehling’s solution, various quantities of salt, and sufficient water to make up 100 c.c., were heated as above described. TABLE I. Cuprous Oxide : Mgrms. Copper : Mgrms. 0.0 5.6 8-0 10.4 5-5 9.3 10.5 11-7 4.9 8.3 9.3 10.4 Table 11. shows the reducing power of furfural at various concentrations and in absence of salt. The weights of cuprous oxide given in column 2 are those found less 595 mgrms., the correction required under these conditions (see Table I.). The weights of copper given in column 3 (a) are those found less 4.9 mgrms., the correction required.The weights of copper given in column 3 (b) are calculated from the weights of cuprous oxide given in column 2. The close agreement between the figures in column 3 (a) and ( b ) shows that there is no necessity to reduce the cuprous oxide to metallic copper. The reducing power of the furfural is not inde- pendent of the concentration, the furfural-copper ratio increasing from 0.362 toBY MEANS OF FEHLING'S SOLUTION 43 0.452, as shown in column 4. This may be the result of mass action ; in presence of 0.05 grm. of furfural, the greater part of the copper in 20 C.C. of Pehling's solution is reduced. I n addition to the results given in the table, fourteen other determina- tions were made with 0.05 grm. of furfural (the maximum quantity employed).I n most cases the results agreed well with those given in the table, but in five cases differences of as much as 4 to 6 mgrms. in the weight of cuprous oxide (Le., 3 to 5 per cent.) were found. 1. Weight of Furf'ural employed : Grni. 0~0100 0~0200 0*0300 0*0400 0*0500 TABLE 11. 4. 2. 3. Weight of Cuprous Oxide (corrected) : Mgrms. 30.8 31.8 57.2 54.8 80.5 81.3 101.7 101.4 126.0 123.7 Weight of Copper (corrected)- (u) Mgrms. found. 37.1 28.0 50.8 48 *G 72.1 72.1 90.1 89.7 111.6 109.6 ( b ) Mgrms. calculated. 27.3 28.2 50 8 48.7 71.5 72.2 90.3 90.0 111.9 109.8 0.362 0.402 0.417 0.444 0.452 In the well-known process of determining pentosans which involves distilling the material with 12 per cent. hydrochloric acid, a distillate containing about 10 per cent.of the acid is obtained. Since, according to Flohil's method of copper reduction, 50 C.C. of the distillate are used, we have determined the reducing power of furfural at varioue concentrations, in presence of a quantity of sodium chroide (8 grms.), equal to that obtained by neutralising 50 C.C. of 10 per cent. hydrochloric acid with sodium carbonate. Table 111. shows the reducing power of furfural at various concentrations in presence of 8 grms. of sodium chloride. The weights of cuprous oxide given in column 2 are those found less 10.5 mgrms., the correction required under these conditions (see Table I.). The weights of copper given in column 3 (a) are those found less 9.3 mgrms., the correction required. The weights of copper given in column 3 (b) are calculated from the weights of cuprous oxide given in column 2. Here again the reducing power of the furfural is not independent of the concentration.44 EYNON AND LANE: THE ESTIMATION OF FURFURAL 1.2. Weight of Weight of Cuprous Oxide (corrected) : Furfural employed : Grm. Mgrms. 29.3 0~0100 28.7 27.0 58.1 0*0200 56.3 58.7 82.5 0.0300 81.9 80.7 103-4 0.0400 106 *9 104.8 125.9 0.0500 127.2 126.5 3 . Weight of Copper (corrected)- (4 Mgrms. found. 25.6 25.4 23.6 50.9 49.2 52.1 72.5 72.0 71.4 91.6 95.4 93.0 - 112-9 110-7 (a) Mgrms. calculated. 26.0 25.5 24 SO 51.6 50.0 51.0 73.3 72.7 71.7 91.8 94.9 92.1 111.8 113-9 112.3 4. Fiirrural Copper -. 0.399 0.394 0.418 0.429 0.445 It is evident from a comparison of Tables 11. and 111. that the reducing power of the furfural per se is independent of the presence of salt-ie., the weight of cuprous oxide obtained by the action of a given weight of furfural on Fehling’s solution in presence or absence of salt, less the weight of cuprous oxide obtained in a blank experiment with the same quantity of sodium chloride, is constant.The values given in Tables 11. and 111. being, therefore, practically the same, they have been employed in plotting the curve shown below ; the points indicated by the small circles represent the mean weights of cuprous oxide from Table II., whilst those indicated by the crosses represent the mean weights of cuprous oxide from Table 111. The values given in Table IV. have been taken from the curve. By means of Tables I. and IV. the quantity of furfural corresponding to the weight of cuproue oxide obtained by the above-described method may be found.We have confirmed Flohil’s statement that the unreduced copper in the liquid after boiling may be determined by Schoorl’s iodometric method (Zoc. cit.). For this purpose the contents of the flask are cooled in running water, treated with 10 C.C. of a 20 per cent. solution of potassium iodide and 10 C.C. of a 25 per cent. solution of sulphuric acidBY MEANS OF FEHLING'S SOLUTION 45 (1.5 parts of concentrated acid to 8.5 parts of water by volume), and then titrated with Fa thiosulphete solution. b Mgrms. of CusO. TABLE IV. 0~0100 0.0200 0~0300 0~0400 0*0500 30.0 57-0 81.0 103-5 125.0 26.6 50% 71.9 91.9 111.0 0.376 0.395 0.417 0.435 0.45046 ESTIMATION OF FCJRFURAL BY MEANS OF FEHLING’S SOLUTION DISCUSSION.The CHAIRMAN (Mr. LING) remarked that the estimation of furfural was of great importance in the estimation of pentoses and pentosans, and two methods had hitherto been available, the furfural being estimated in the one case as phenyl hydraeide, and in the other as phloroglucide. Both of these methods emanated from Professor Tollens. The estimation as phenyl hydraeide was very uncertain in its results, and the phloroglucide method was more satisfactory, but phloroglucinol was a somewhat expensive substance. He had tried the copper-reduction method some years ago, but had not been successful with it. He had applied it in what seemed to him to be a rational manner, by adding an excess of Fehling’s solution and heating the mixture in a closed vessel for a certain time in the water-bath.About twelve months ago, however, Flohil had found it possible to obtain much better results by usin a reflux condenser, and it was at his (Mr. Ling’s) suggestion that the present authors undertook the revision of Flohil’s results under the Society’s Research Scheme ; and having seen their experiments and read their paper, he must say that he considered their investigation to be an ideal one from the point of view of the Research Scheme. Such a method had been much needed, and, as the result of Messrs. Eynon and Lane’s work, it was rendered quite as satisfactory as the phloroglucinol method, whilst it had the additional advantage of being more e~peditious. Mr. A. E. PARKES asked whether it would be possible to apply this method t o the determination of furfural in spirits. The CHAIRMAN observed that, the method being a reduction method, could not be used in the case of spirits, which contained other reducing substances as well as furfural. Dr. SCHIDROWITZ remarked that some ten years ago Dr. Hewitt had tried a method of this kind for the estimation of aldehydes in spirits, but had found it to be inapplicable owing to the smallness of the quantities of aldehydes that were present. Mr. A. CHASTON CHAPMAN asked at what degrees of furfural concentration the respective ratios of 0.376 : 1 and 0.450 : 1 were obtained. Mr. W. BACON asked what were the limits of concentration most applicable to this process. Mr. EYNON, in reply, said that the ratio of 0.376 : 1 was obtained at a furfural concentration of 0.01 grm. in the reaction mixture, and that of 0.450 : 1 at a concentration of 0.05 grm. The quantity of furfural present must be within the limits of 0.01 and 0.05 grm., unless a larger quantity of Fehling’s solution be taken, and then, of course, the tables they had given would not apply.

ISSN:0003-2654    

DOI:10.1039/AN9123700041

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年代:1912

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MILLER : COMPOSITION OF AUSTRALIAN (VICTORIAN) MILK 47 Total Solids. % % 13.33 13.07 12.90 i2.58 11-72 12.03 12.S8 13'46 13-37 13.28 13.31 12-97 12.96 COMPOSITION OF AUSTRALIAN (VICTORIAN) MILK. BY E. HOLL MILLER. (Read at the Meeting, December 6, 1911.) THE average composition of 11,140 samples of milk from farms, analysed in the Anglo-Australian Milk-Preserving Company's laboratory during the year September, 1909, to August, 1910, inclusive, is given in the following table. The period chosen is one complete year ; spring embraces the months September to November, summer December to February, autumn March to May, and winter June to August. Fat. 4-16 3-99 3.97 4-08 4.03 4-02 4.23 4'71 4-61 4'41 4.35 4'24 4.23 Morning Milk. Evening Milk. Mean. Approxi- mate Corre- sponding English Month.Solids. not- Fat. 3olids- not- Fat. Solids. not- Fat. Total Solids. - Fat. Totitl Solids. - Fat. Sp. Gr. Sp. Gr. Sp. Gr. 1909. September October ... November December 1910. January . . . February March ... April ... May ... June ... July ... August ... % 12-94 12-74 12.71 12.40 11.71 12.02 12.74 13.14 13.02 12.84 12.74 12-39 % 3.90 3 -86 3-92 4.01 4-02 4.05 4-15 4-46 4.43 4-15 4-00 3.90 % 9-04 8.88 8.79 8.39 7.69 7.97 8-59 8.68 8-59 8 -69 8-74 8-49 x 9-17 9-08 8-93 8.50 7.69 8.01 8-65 8.75 8.76 8.87 8-96 8.73 % 13-13 12.90 12 -80 12-49 11 -71 12.02 12.81 13'30 13-19 13.06 12.90 12-68 % 4.03 3-92 3.94 4-04 4-02 4-03 4.19 4-58 4-52 4-28 4.17 4.07 % 9.10 8'98 8-86 8 *44 7.69 7.99 8-62 8.72 &-66 8-78 8-73 8.61 1.0325 1 *0319 1.0315 1.0298 1.0270 1.0281 1.0305 1.0306 1.0303 1.0309 1.0312 1 *0303 1 -0328 1.0326 1 -0320 1.0302 1 -0270 1.0283 1 -0307 1.0307 1.0308 1-0314 1.0318 1.0310 1.0326 1.0322 1'0317 1'0300 1.0270 1 -0282 1.0306 1.0306 1.0305 1-0311 1 *0315 1-0306 February.March. April. May. June. July. August. September. October. November. December. January. Average ... 1 -0304 12.62 4-07 - 8 -55 1-0310 8.70 1.0307 12-79 4'15 - 8.62 It will be noticed that the poorest milk occurs in the month of January, which month approximates to the English month of June. The average difference between morning and evening fat is 0.16 per cent. This figure is lower than that given by Richmond for English milk-vie., 0-35 per cent. It will be noticed that the evening milk is the richer in fat, while the sp. gr. of the morning's milk is lower than that of the evening's milk.With English milk the sp. gr. of the morning's milk is generally higher than that of the evening's milk. On comparing the mean average composition with that given by Richmond ("Dairy Chemistry ") for English milk, the ~ p . gr. is found to be lower, and the fat higher. The lowness of sp. gr. for the months of December, January, and February, is ascribed to a flush of green herbage caused by copious rains. Aldehyde Figure.-The aldehyde figure of a considerable number of the above samples has been found to average 1 8 . 5 O using Tv strontia, and 17" using & soda.48 MILLER : COMPOSITION OF AUSTRALIAN (VICTORIAN) MILK This is a ratio of approximately 1.1, and corresponds with the results of Richmond and Miller (ANALYST, 1906, 31, 224).has been found to be 0.173 (using strontia), the figure given protein The ratio aldehyde I t was found that milk curdles on boiling when it had developed an acidity of This figure is in accordance with that given by by Richmond (ANALYST, 1911, 36, 9) being 0.170. 13' above its normal acidity. Harrison and Richmond (ANALYST, 1900, 25, 116). The following curve graphically illustrates the souring of milk : Time. 6 16 23 25 27 31 33 50 53 Acidity. 0 4 20 33 49 50 55 61 63 TIME (HOURS). It will be noticed that there is the usual break in the curve, occurring at 45" and Acidity.-The average normal acidity was found to be 18". Ash.-The percentage of ash determined from a considerable number of samples C1, CaO, and P20,.-The average percentage of these constituents was found to A sample of tinned sterilised milk of German origin, imported into Java, gave corresponding to the acidity at which the micro-organisms cease to increase. was found to average 0.72 per cent. be as follows : C1, 0.08 per cent. ; CaO, 0.18 per cent. ; Ps05, 0.21 per cent. the following results on analysis : Sp. gr. ... ... 1'0325 Total solids ... . . . 12-21 per cent. Fat (Gottleib) ... ... 3.21 ,, Ash ... ... ... 0.72 ,, Solids-not-fat . . . ... 9.00 ,, Protein (N x 6.38) ... 3.60 ,, Lactose . . . ... ... 4.68 ,, Acidity ... ... 23' Aldehyde figure ... 21' (strontia) ... 0.171 . protein Ratio -~ aldehyde C blorine ... ... 0.090 ... 0.160 CaO ... ... P,O, I.. ... ... 0-230

ISSN:0003-2654    

DOI:10.1039/AN9123700047

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年代:1912

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COMPOSITION OF AUSTRALIAN SWEETENED CONDENSED MILK 49 COMPOSITION OF AUSTRALIAN SWEETENED CONDENSED MILK. BY E. HOLL MILLER. (Read at the Meeting, December 6, 1911.) THE following two tables give the composition of sampIes of five different brands of sweetened condensed milk purchased in Victoria, and six purchased in New South Wales. These figures are of some interest, as all the milks were manufactured in Australia. TABLE I . Purchased in Victoria. Brand No. 1. Brand No. 4. Brand No, 5. lample c. Brand No. 2. Brand No. 3. Sample a. Sample b. lample a. Sample b. Total solids ... Fat ,.. ... Ash ... ... Solids-not-fat . . . Protein(N x 6-38) Total sugars ... Chlorine ... Acidity ... ... 72-18 10-03 1.91 62.15 9.68 50-56 0.19 43.8" 72.96 11-41 1.90 61.55 9.20 50.45 0.18 51' 73.740 10.800 1.870 61.940 9-300 50.700 0.188 46.9' 76.80 10.50 2-04 66.30 9.69 54-59 0.18 48-6" 76.24 10-63 2.01 65-61 10.12 53-48 0.24 49-4" 75-00 10.11 1.93 64-89 9-69 53-27 0.23 46.5" 74.99 10.27 1.90 64-72 9.00 53-82 0.22 45*5O 74.74 9.61 1.94 65.13 9-05 54-14 0.23 45.6" TABLE 11.Purchased in New South Wales. I Brand No. 1. Brand No. 2. Brand No. 3. Brand No. 4. Brand No. 5. Brand No. 6 . 75-87 10.68 2-10 65.19 10-25 52-84 0-36 5 1 O 67-53 9-41 1-82 58.12 9-14 47.16 0-20 56-8" 76-14 9.28 2.11 66.86 9-84 59-91 0.21 51-84' 74.77 9.81 1.82 64.96 8-95 54.19 0.19 44-64' 71-38 9.93 1-84 61-45 9-39 50.22 0.19 50-05" 75-87 9.05 2.10 66-82 9.10 55-62 0.24 49.75" Total solids ... Fat .., ... ... Ash ... .., ... Solids-not-fat . . . Protein (N x 6.38). . . Total sugars ...Chlorine ... ... Acidity ... ... For analysis the whole of the contents of the tin were turned out into a, basin and thoroughly mixed, and the portions required were taken from the mixed sample.50 MILLER: THE ALDEHYDE FIGURE OF BUTTER The fat was estimated by Richmond’s modification of the Rose-Gottleib method. Other constituents were estimated in the usual manner. Tyrosin was detected in all the above samples with the exception of Nos. 1 and 3, Table I. I have found that tyrosin makes its appearance in sweetened condensed milk between the end of the third and fourth month after manufacture. Samples six months old show distinct crystklline tufts of tyrosin, which can generally be detected on the first slide prepared, when examined under the microscope with a one-sixth inch objective. Samples twelve months old show fairly large round crystalline feathery tufts. These tufts of crystals all approximate to the same size in the same tin of milk, and the size and number of them form a fairly good criterion of the age of the sample.

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DOI:10.1039/AN9123700049

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年代:1912

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50 MILLER: THE ALDEHYDE FIGURE OF BUTTER THE ALDEHYDE FIGURE OF BUTTER. BY E. HOLL MILLER. (Read at the Neeting, December 6, 1911.) IT has been pointed out by Steinegger that formaldehyde combines with milk proteins to form additive compounds, probably of the type R<Coo&, with an increase in the acidity of the milk, which is proportional to the total nitrogen present. Steinegger's method has been modified by Richmond and Miller (chiefly by substituting the use of strontia for soda), who have shown that under their conditions the method is a rapid and approximately accurate one for estimating the percentage of proteins in milk ; and it has been further shown by Richmond (ANALYST, 1911, 36, 9) that the degree of accuracy of the determination is of the same order as the Gerber method for the estimation of fat.A number of experiments have been carried out in order to determine whether use could be made of this method to estimate with a, fair degree of accuracy the pro- teins in butter, as it was recognised that a rapid method for such would be of considerable value in butter-factory routine analysis. The following procedure was found to be the best for carrying out the determina- tion : Approximately 10 grms. of butter are weighed into a tared beaker, which is placed in a water-bath at 60" to 70" C., until the butter is completely melted. Twenty-five C.C. of water at about 65' C. are added, and followed by 1 C.C. of a 0.5 per cent. solution of phenolphthalein. The contents are well agitated. Approximately $a alkali is then run in until a faint permanent pink tint is formed.If it is found that the end point is masked by the yellow colour of the butter-fat, the contents of the beaker should be allowed to settle, and the bottom aqueous layer observed, and the addition of alkali continued until the pink tint is obtained. Five C.C. of strong formaldehyde solution are next added, and the contents NCHMILLER: THE ALDEHYDE FIGURE OF BUTTER 51 Protein (Kjeldahl, N x 6 '38) per Cent. of the beaker well agitated; ;G strontia is then run in until the pink tint is again produced in the aqueous portion. The number of C.C. of ZG alkali used in the second titration, less the amount equivalent to the acidity of the formaldehyde solution added, is proportional to the protein present. One C.C. of & strontia is equivalent to 0.01355 grm. of protein nitrogen, assuming the proportion of casein to albumin to be 7 to 1 (Richmond and Miller, ANALYST, 1906, 31, 224). Thus, when 10 grms. of butter are taken, the number of degrees of acidity pro- duced when multiplied by 0.170 gives the percentage of protein. The following are some of the results obtained : Ratio Protein Protein calculated, Aldehyde. O Aldehyde x 0.170. Difference* SALTED BUTTER ONE MONTH OLD, PREPARED FROM RIPENED CREAM. Aldehyd: Figure, . 3.50 3.00 4-00 3.50 5.00 4.13 0.620 0.495 0.690 0.600 0.860 0.720 0.177 0.165 0.172 0.171 0.172 0.1 74 0.595 0.510 0.680 0.595 0.850 0.700 - 0.025 + 0.015 - 0-010 - 0.005 - 0.010 + 0.020

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DOI:10.1039/AN9123700050

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年代:1912

数据来源: RSC

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MILLER: THE ALDEHYDE FIGURE OF BUTTER 51 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Estimation of Water in Butter. A. C. D. Rivett. (Chem. News, 1911, 104,261-263.)-The author employs the calcium carbide method, and determines the loss of acetylene by weighing, thus arriving at the amount of water present in the sample. A special form of apparatus is employed, in which a known weight of the butter in a lower chamber can be heated, in the weighed apparatus, after allowing it to become mixed with a quantity of calcium carbide placed in an adjacent chamber. The acetylene passes through a tower of glass-wool mixed with carbide, which traps any moisture, and is finally swept out of the apparatus by means of a current of dried air. Experiments show that 0,696 grm.of acetylene represents 1 grm. of water (theory = 0-722 grm. C2H2), and the calculation is made on this basis. The butter and carbide mixture should be heated with the direct flame to a temperature similar to that ordinarily reached in the direct heating method. The results are usually 0.2 to 0.3 per cent, lower than by the last-named method, in which probably volatile52 ABSTRACTS OF CHEMICAL PAPERS matter other than water-vapour escapes during heating. The method of heating butter with alcohol at 100" C. to expel the water gives results about 0.1 per cent. higher than the carbide method. A. R. T. Influence of Certain Preservatives on the Keeping Properties and Composition of Butter. K. Fischer and 0. Greunert. (Zeitsch. Untersuch. Nahr.Genussrn., 1911, 22, 553-582.)-Parallel experiments carried out on the effect of various substances on the preservation of butter and margarine showed that benzoic acid, salicylic acid, and boric acid, failed to prevent the butter and margarine from becoming rancid after the lapse of a short time, even when added in quantities up to 1 per cent. On the other hand, butters and margarine containing 3 per cent. of common salt remained fresh as regards taste and odour for from two to three months. The changes taking place in the butter and margarine containing the first- mentioned substances were due to decomposition of the glycerides and the proteins ; this decomposition was not decreased proportionally to the quantities of the preservative substances added. w. P. s.Estimation of Cocoa-Husks in Cocoa. C. Ulrich. (Arch. Pharm., 1911, 249, 524-597.)-Analyses of many samples of the different kinds of cocoa upon the market are given, and the methods of estimating cocoa-husk are critically examined (cf. ANALYST, 1909, 34, 134). The iodine value of the fat of the roasted beans examined ranged from 32.20 to 35-6 (mean, 34*1), whilst in the case of unroasted beans the limits were 34.7 to 36.5 (mean, 35.5). Prochnow (Dissertation) confirmed the results of Welmans (2. oflent. Chem., 1901, 7, 500), that the fat from the shells had a considerably higher iodine value (43.2 to 46.2 for six samples) than the bean fat; but the author has obtained lower values than these-34.8 to 37.9 (mean, 36-3) for the fat from roasted shells, and 36 to 38 (mean, 37.3) for the fat from unroasted shells.Hence it is not possible to detect the presence of even 30 per cent. of husks, as claimed by Welmans, by means of the increase in the iodine value of the fat, With regard to the elutriation method of separating the husk, devised by Filsinger and Drawe (ANALYST, 1903, 28, 216), the author's experiments indicate that as little as 7.5 per cent. of added husk may be detected and estimated in normal cocoa (30 per cent. of fat and moisture), provided that the husk is present in a very finely powdered condition, and that the factor (for the loss) of 1.43 proposed by Drawe be increased to 1.72. Estimation of the amount of crude fibre by the method of Konig (ANALYST, 1898,23, 47), and the modification of Matthes and Muller (ANALYST, 1906, 31, 362), gave the following results with eight different kinds of cocoa: Roasted kernels 5.79 to 7.9, and roasted husks 13.5 to 17-7 per cent., calculated on the fat- free substance.The method would not enable a smaller quantity than 27.5 per cent- of husks to be detected. In like manner, estimation of the pentosans (see Hehner and Skertchley, ANALYST, 1899, 24, 178) is only of value in the case of mixtures containing more than 25 per cent. of husk. The following new method, based on the precipitation of cocoa-red by means of ferric chloride from an acetic acid extract of the cocoa, is claimed to detec with certainty the addition of 10 per cent. and upwards of cocoa-husks to a normal cocoa: One grm. of the finely-powdered,FOOD AND DRUGS ANALYSIS 53 anhydrous, fat-free sample is boiled for three hours beneath a reflux condenser with 120 C.C.of pure 50 per cent. acetic acid, after which the contents of t'he flask are cooled, made up to 150 c.c., well shaken, and allowed to stand for at least twelve hours. The liquid is then filtered, and 135 C.C. of the filtrate are treated with 5 C.C. of concentrated hydrochloric acid and 20 C.C. of 20 per cent. ferric chloride solution, then boiled for ten minutes under a reflux condenser, rapidly cooled, and transferred to a beaker. After standing for at least six hours, the precipitate is collected upon a dried tared filter, washed until the washings are free from iron, dried for six hours at 105" C., and weighed. The following results, calculated upon the anhydrous and fat-free cocoa-beans and upon the original air-dried material, were thus obtained : Cocoa.Accra ... ... Ariba ... ... Bahia ... ... Ceylon ... Guayaquil . . . Samoa ... St. Thome ... Trinidad Mixture of ali" Estima- tions. 6 18 14 6 12 12 18 12 7 Roasted Beans. Ferric Chloride Precipitate. Extremes. Per Cent. 13.07-13*69 12'77-13 *97 10 *71-12 '49 13-67-13 *89 15 '13-16 -82 13 '82-14 '84 13.1 1-14 '27 13 '51 -14 '56 13*02-13*78 Mean. Per Cent. 13-52 13.50 11.39 13.79 16.11 14.34 13'75 14'11 13.51 0 11 Original Material. Per Cent. 6.34 6.99 5-47 6.45 7.48 6'69 6-12 6-14 5.81 Estima- tions. 3 3 3 3 3 3 1 - - Raw Beans. Ferric Chloride Precipitate. Extremes. Per Cent. 14 $6-15 '07 12 -22-1 2 *56 12.1 3-12-73 16*44-17'08 14 -80-15 *O 13 '1 1-13.36 - - 14-33 Mean.Original I Mazial. Per Cent. 14'82 12.82 12'40 16.67 14-90 13.26 14.33 - - Per Cent. 6 '29 5 -84 5.59 7.31 6 *49 5.91 6 -33 - - Extracts of the husks gave no precipitate under the same conditions, whilst mixtures of the different kinds of cocoa with 10 per cent. of husks gave results corresponding within 0.9 per cent. of the calculated smaller amounts of precipitate, Bahia and Guayaquil cocoa thus give results deviating considerably from those of the other kinds of cocoa, but it is pointed out that, in practice, commercial (normal) cocoa usually consists of a mixture of two or more brands, and that in the case of such mixtures the method will readily detect 10 per cent. of husks. If the cocoa is known to be a Bahia product alone, the amount of the precipitate must be as low as 9.68 per cent.before the presence of 10 per cent. of husk is indicated. I n like manner, in the case of Guayaquil cocoa it is also necessary to know the brand, since otherwise a precipitate of 13.70 per cent., as obtained from a mixture of that cocoa with 10 per cent. of husks, would indicate a pure sample. Not until as much as 21 per cent. of husks has been added to Guayaquil cocoa does the iron method give a value of 11-28, which in the case of a normal cocoa would indicate the presence of 10 per cent. of husk. C. A. M. Composition of Honey from Various Countries. K. Lendrich and F. E. Nottbohm. (Zeatsch. Untersuch. Nahr. Genussm., 1911, 22, 633-643.)- The following average results were obtained on the analysis of sixty-three samples54 ABSTRACTS OF CHEMICAL PAPERS of honey imported into Germany, the samples being taken either from the packages in the holds of the vessels or in the Customs warehouses : From Nagpur, India.Acidity ' C.C. 2 Qlkali $er .OO Grms.: Fat pre- pared in India. Sodium Chloride. 46 0-857 189.8 57.6 94-2 0.2 2.0 43-2 - Invert Sugar. - 0-870 20 *o 194.4 76.8 86.7 1.0 1.7 36-0 Non- Sugars. Proteins NX6.25). Country of Origin. Water. Ash. lucrose I Per Cent. 19.81 17-20 16.51 17.37 19.62 19.37 19.98 18.64 19.24 17.84 15-32 14.59 21-34 18-26 Per Cent. 0.30 0.06 0.53 0.22 0.19 0.30 0-25 0.45 0-39 0-20 0.32 0.05 0.63 0.29 Per Cent. 75.86 76-62 80.18 74-15 72.81 74.25 73.58 73.85 76.45 76 *43 75.47 69.60 81-56 75-42 Per Cent. 0.15 3.19 1.76 2.46 1-59 1.52 1.49 1.29 1.22 1.41 0.22 0.04 5-36 1.48 Per Cent.4.18 2.99 1-51 6.03 5-97 4.85 4.96 6.25 3.08 4-32 6.98 0.94 8.86 4.65 Per Cent. 0.58 0.21 0.17 0.28 0.46 0.50 0-39 0.43 0.40 0.50 0.28 0.12 1.07 0.38 France (2 samples) Italy (1 sample) ... Hawaii (8 samples) C a l i f o r n i a (8 Mexico (4 samples) Jamaica (9 samples) Hayti (2 samples) SG. Doming0 (5 Peru (7 samples) . . . Chili (14 samples) Australia (4 samples) All samples : Minimum ... Maximum ... samples). . . ... samples). . . ... Average . .. ... 3-50 1.80 0.86 2.39 2.50 2 -69 2.70 2.08 2.86 2-83 1.13 0.60 5.90 2.30 Only one of the samples yielded a positive reaction with Fiehe's test. This sample contained no diastase, was dark brown in colour, and had evidently been overheated in manufacture, w. P. s. Bassia Kernels and Fats.(Bzcll. Imp. Inst., 1911, 9, 228-236.)-The seeds The following come into the market under the name of " mowra " and " illipe " seeds. table shows the constants of the fats from some authentic samples : Bassia Latifo Zia. Bassia Longif0 Zia. Bassia Butyracea. Bassia Z;ongifoZia. Sample of,, " Mee Oil as received 'rom Ceylon. Fat from Madras, prepared in India. From Gonda, United 'rovinces. From Gonda, prepared in India. From MadraR. Yield of fat per cent. from kernels ... 57 -8 0.861 19.7 195.3 60.0 95'5 2B5 1 -4 45.0 61 -2 0.856 59.6 200.0 39.6 96.6 nil 2.2 51.5 - 0.864 5.0 198.2 60.0 87'4 3-6 2.1 36.0 - 0.862 20.7 195.3 42.7 94.6 4.3 2.5 48 *2 - 0.861 25.7 191.5 61-2 - - - 40.2 loo" c. Sp. gr. at - ... ... ... 15.5" C. Acid value ... ... ... ... Saponification value .. . . , . . . , Iodine value, per cent. ... ... Hehner value, per cent. ... ... Reichert-Meissl value . . . . . . Unsaponifiable matter, per cent. . . . Titer test, " C. ... ... ...FOOD AND DRUGS ANALYSIS 55 The fat from B. butyracea is harder and whiter than that from the other two species, :but it is not exported, the available supply being consumed locally. Bassia kernels at present are chiefly crushed in France and Germany, since in England the expressed cake is considered poisonous for cattle. It has been shown (Bio-Chemical J., 1910, 93) that such cake contains a saponin-like glucoside with marked physiological activity when subcutaneously injected, but apparently without action when fed to cattle. H. F. E. H. Charaeteristies of Palm Oil from Different Varieties of Palm.A. Hebert. (BUZZ. SOC. Chim., 1911, [iv.], 9, 1083-1085.)-The samples of palm oil examined were extracted by means of petroleum spirit from the fruit of palm-trees grown in Dahomey. All the fats are used by the natives as food, with the exception of that obtained from the variety repanda, which is reputed to cause headache and sickness. The yields and analytical values were as follows : FAT OF Ehis Gwineensis. Oil from pulp, per cent. . . . . . . Oil from whole fruit, per cent. Melting-point of fat, O C. ... Sp. OT. at melting- p2nt ... ,.. Saponification value ... ... Reichert value . . , Iodine value . .. Hehner value ... Melting-pointo of fatty acids, C. Variety ?ommunu, 41'0 22.0 42.0 0.882 201.0 0.8 43.8 98.0 46 -0 Sub-species 6.Nigrescens. Variety Vulgaris. 43.0 21.0 42.0 0.881 201 .o 0.8 48.0 96-2 48'0 47.0 29.0 43'0 0.888 196.0 0-8 52.2 96'2 48.0 Variety Semper- nigru. 52.0 16.0 44.0 0.892 196.0 0.9 52.2 98.1 48-0 Variety Pisijera. 59.0 42 -0 45.0 0.891 197.0 1-3 50.2 97.7 47'0 Analysis of Mustard Flour. A. Domergue. 60.0 56.0 44.0 0.889 210.0 1 '1 45-6 97-8 46.5 Sub-species 6. Vireseens. Variety Repanda. 63.0 32.0 43'0 0.884 196.0 0 '8 52 -1 95.0 44.0 Variety Gracili- nux. 52.0 30.0 42'0 0.889 198.0 1'1 55'6 97.7 44.0 Com- mercial 'alm Oil. - - - )*945 at 15" C. !02.0 0-5 52.0 95.0 47-0 C. A. M. (J. Pharm. Chim., 1911 [vii.], 4, 494-496.)-1n estimating the proportion of essential oil in mustard flour it is necessary to prevent the distilling vapours coming into contact with rubber connections.For this purpose the author employs an apparatus in which one end of the condenser is connected with the flask by means of a ground-in stopper, whilst the other end is bent downwards a t a right angle into a graduated cylinder. From 60 to 65 C.C. of the distillate are collected as described by Lenormand, after which 20 C.C. of & silver nitrate solution are added, the volume made up to 100 C.C. and the estimation56 ABSTRACTS OF CHEMICAL PAPERS completed. samples of mustard flour are from 0.2 to 0-9 per cent. 0.70 per cent. as the minimum for black mustard seed. The proportions of essential oil most usually found in commercial The French Codex specifies C. A. M. Composition of Capsicum (Cayenne Pepper). A. von Sigmond and M. Vuk. (Zeitsch. Untersuch.Nahr. Genussm., 1911, 22, 599-605.)-Analyses of twenty-five samples of Hungarian capsicum yielded the following results : Pevicarp : water, 16.6 ; ether extract (on the dry substance), 14.6 to 15.0 per cent. ; iodine value of the oil, 134. Seeds: water, 6.0; ether extract, 31.8 to 33.4 per cent. ; iodine value of the oil, 140. Green, Portions (stalks, etc.) : water, 9.1 ; ether extract, 2.5 to 2-6 per cent. ; iodine value of the oil, 110.0 to 112.6. Analyses are also given of specimens of Turkish, Spanish, Japanese, and Indian capsicums; the quantities of the various constituents varied considerably, the ether extract ranging from 9.2 to 10.47 per cent., and the ash from 8.19 to 9.46 per cent. for the fruit free from seeds, whilst samples of ground capsicums yielded from 15.5 to 22.08 per cent. of ether extract and from 5-63 to 9.86 per cent. of ash. As regards the detection of added oil in ground capsicums, the author is of opinion that this cannot be done by taking the iodine value of the oil extracted from a sample. As this added oil would remain on the outer portions of the particles constituting the powder, whilst the natural oil would be still partly enclosed in the cellular tissue, it might be possible to separate the added oil by shaking with water, and the authors are carrying out experiments in this direction. It is pointed out that the United States regulations require that ground capsicums, excluding seeds, shall yield not less than 15 per cent. of ether extract; this portion of the fruit, however, according to the authors’ analyses, contains only 14-5 per cent. of ether-soluble substances. w. P, s.

ISSN:0003-2654    

DOI:10.1039/AN9123700051

出版商:RSC    

年代:1912

数据来源: RSC

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56 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Antiseptic Effect of Creosote Oil and Other Oils used for Preserving Timber. J. M. Weiss. (J. SOC. Chem. Ind., 1911,30,1348-1353.)-The author has investigated the behaviour of pure cultures of B. subtilis, Sacch. glutinis, and Penicillium sp., all of which can grow on moist sterile wood towards three classes of antiseptics : (1) Oils prepared in the laboratory, mostly separated creosote oil with varying proportions of filtered tar or tar acids added; (2) pure substances such as phenol, cresol, naphthalene, anthracene, quinoline, and paraffin ; and (3) commercial creosoting oils. I n no case was the antiseptic used in higher proportion than 10 per cent. in the medium, the lowest dilution being 0.05 per cent.A culture medium composed of Liebig's extract, peptone, sodium chloride, maltose, lactose, dextrose, and calcium nitrate in agar was used. The author's conclusions are as follows: (1) The neutral oils of creosote are strong antiseptics ; (2) the middle fraction of these neutral oils, boiling from 235" to 270" C., is the strongest : the higher boiling oils are considerably weaker, the lower oils slightly so; (3) coal-tar bases having high boiling-points are strong antiseptics ; (4) coal-tar acids are very strong antiseptics, rising in efficiency with the boiling-point ; ( 5 ) the solid hydrocarbons, naphthalene and anthracene, have low antiseptic values; (6) the addition of filtered tar i nBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 57 moderate amounts to creosote does not materially reduce its antiseptic value ; (7) paraffin has no antiseptic value; (8) producer gas-tar distillates have lower antiseptic value and are decidedly inferior to the neuiiral coal-tar oils ; (9) coal-tar creosote is greatly superior as an antiseptic preservative to producer gas-tar distillates and petroleum residues.H. F. E. H. Use of Charcoal as a Clarifying Agent in the Estimation of Sugar in Urine. A. C. Andersen. (Biochenz. Zeitsch., 1911, 37, 262-265.)-The results of a number of experiments carried out by the author show that the addition of hydro- chloric acid, as recommended by Bang and Bohmannsson (ANALYST, 1910, 35, 70), does not prevent the absorption of sugar by blood-charcoal when the latter is employed for clarifying and decolorising urine. When bone - charcoal is used but little absorption takes place, the quant,ities of sugar found being practically identical with those obtained by using lead acetate or mercuric nitrate as clarifying agents ; bone-charcoal, however, decreases the reducing power of normal urine to a less extent than does blood-charcoal. More satisfactory results are obtained if 50 per cent.acetic acid be employed in place of hydrochloric acid, 8s the absorption of the sugar by either bone or blood charcoal is almost entirely prevented. Forty C.C. of the urine should be treated with 10 C.C. of 50 per cent. acetic acid and 4 grms. of powdered blood-charcoal, shaken for tan minutes, and then filtered. w. P. s. Observations on the Assay of Digestive Enzymes. H. T. Graber.( J . Ind. Eizg. Chem., 1911, 3, 919-921.)-According to the U.S. Pharmacopceia, the activity of pepsin preparations is to be tested on fresh eggs,’’ but the author has found that the digestibility of egg albumin varies considerably according to the age of the egg. The albumin of an egg twenty-four hours old is not in a readily digestible condition, and the maximum condition of digestibility by pepsin is only reached when the egg is five to seven days old; after this the digestibility decreases, and about the tenth day it becomes the same as it was on the second day. I t is advisable to retain a sample of pepsin standardised against eggs of known ages, and to use the same for control purposes in future work. I n digestion experiments with pepsin extremely small variations in acidity cause large differences in the results.In testing the diastatic activity of pancreatin, various kinds of starch show very different results-for instance, a sample of pancreatin may show an activity towards potato starch one-third greater than towards maize starch. In testing papain, finely- minced raw beef-steak should be used; the enzyme does not dissolve cooked beef, Ten grms. of minced beef, 0.325 grin. of papaln, and 85 C.C. of 0.3 per cent. hydro- chloric acid, are digested at 52” C. for six hours; the undigested residue, after settling in a, measuring-tube for three-quarters of an hour, should not amount to more than 2 C.C. The coagulating power of rennet is influenced by the condition of the milk and its chemical composition, particularly the proportion of calcium salts ; also the manner of mixing the rennet with the milk, the kind of cows from which the milk was taken, and, lastly, the temperature at which the milk was kept before and during the test.The milk should not be stirred, but the rennet should be mixed by pouring from one vessel to another. J. F. B.58 ABSTRACTS OF CHEMICAL PAPERS Diastatic Power of Malt. C. G. Matthews and F. E. Lott. (J. Inst. Brew., 1911, 17, 638-642.)-The Lintner process for estimating diastase measures only the saccharifying power, since soluble starch is employed, and this the authors consider a defect, as failing to take account of the starch-liquefying power of the extract. Soluble starch, if over-converted, yields results which axe too high ; while soluble starches prepared from malt, barley, and potato starches all yielded the same result with the pale malt used. The use of potato starch paste in place of soluble starch is shown to be satisfactory for the majority of malts examined, the average difference being 3.5 units Lintner, the maximum discrepancy being a fall of 16 per cent.with a vinegar malt (D.P. 99.5). Two malts of normal diastatic activity showed values of 3 and 5 units higher when starch paste was employed. The authors describe the method they recommend, which consists in adding 0.75 grm. of finely-ground malt to 500 C.C. of 2 per cent. starch paste, standing one hour at 70' F., checking the action with soda, diluting to 1 litre, and then titrating the maltose formed with Fehling's solution, the grains being allowed to settle out without filtering. For highly diastatic malts the concentration of starch may be increased to 3 per cent. The vinegar malt mentioned above shows a value of 20 per cent. low by this method (2 per cent. starch), and 11 per cent. low with 3 per cent. starch. The other samples examined show an average difference of 7 units Lintner, the new process values being in all cases but one lower than the standard values. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9123700056

出版商:RSC    

年代:1912

数据来源: RSC

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58 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Estimation of Asphalt in Mineral Oils, Pitch, etc. F. Schwarz. (Chem. Zeit., 1911, 35, 1417-1419.)--The author recommends the use of butanone (methylethyl ketone) for the separation of asphalt from mineral oil distillates, lubricating cylinder oils, etc. Dry butanone has a sp. gr. of 0.805 at 20" C., but its solvent action is too powerful to permit of a proper separation of the asphalt, especially in presence of a large proportion of oil. A litre of butanone dissolves about 110 C.C. of water at the ordinary temperature, and the saturated mixture has a sp. gr. of 0.835 at 20" C. For the treatment of thick mineral lubricants, a preliminary extraction with saturated aqueous butanone, followed by extraction with aqueous butanone of sp.gr. 0.812, affords a satisfactory separation of the hard asphalt. Two to 4 grms. of the oil to be tested are placed in a 200 to 300 Erlenmeyer flask, fitted with a fractionating column tube, together with 40 to 80 C.C. of saturated aqueous butanone; the contents of the flask are boiled with vigorous agitation for one minute, and the solution is decanted off hot through a No. 589 filter, care being taken to leave all the residual oil in the flask. The operation is repeated twice again with 20 to 40 C.C. of the saturated butanone. Next, the oily residue is treated in exactly the same manner, three times, with aqueous butanone of 0.812 sp. gr., the same filter being used and the extracts collected separately or together with those of the first series. Any oily particles on the filter should be thoroughly washed with the final hot extraction liquid.The residue in the flask is then dissolved in benzene or chloroform, and the solution is poured through the same filter into a dish. The residue after evaporation often contains traces of oily matters, which should beORGANIC ANALYSIS 59 removed by treatment with 5 to 10 C.C. of light petroleum spirit (h.p. 30" to 50" C.); the asphalt is filtered off, washed with the same spirit, dissolved in chloroform or benzene, and collected in a tared dish; it should be quite hard and brittle a t 100" C. The results are usually lower than those obtained by the alcohol-ether method, but the latter generally yields soft asphalts containing bodies not included in the hard asphalt separated by the butanone method, The butanone method may likewise be employed for the fractionation of solid bituminous materials and pitch residues.About 1 grm. of the bitumen, soluble in chloroform, is treated as described four or six times, each time with 20 C.C. of butanone of sp. gr. 0.812. The extraction with the saturated aqueoils butanone of sp. gr. 0.835 may be omitted with these materials, since the quantity of oily constituents is relatively small. The extracts are filtered hot, and the filter is washed with the same solvent ; the asphalt is then dissolved in chloroform and filtered into a tared dish. The matters in the butanone extract may be further fractionated by saturating the extract with water (about 10 C.C. of water per 100 c.c.). The precipitated resins are filtered off, washed with saturated aqueous butanone, and weighed separately, the oily constituents being estimated by evaporating the butanone extract.J. F. B. Analysis of Mixtures of Ceresin and Paraffin Wax. N. Chercheffsky. (Ann. de Chim. anal., 1911, 16, 456-463.) --The lowering of the melting-point caused by the addition of paraffin wax to ceresin is sometimes disguised by adding carnauba wax or a similar product. Hence it is necessary in the first place to separate the unsaponifiable matter in the sample by the usual methods. The following table shows the comparative solubility of a typical paraffin wax (melting-point 52" to 54" C.) and of a pure Galician ozokerite ceresin (melting-point 68.7" C.) in different solvents at 15O C. Solvents.Ethyl alcohol, 96.5 per cent. ... ... Methyl alcohol, 99.25 per cent. ... ... Amy1 alcohol ... ... ... ... ... Carbon bisulphide ... ... ... ... Carbon tetrachloride ... ... ... ... Chloroform . . ... ... ... ... Crystallisable benzene ... ... ... Acetone ... ... ... ... ... Ether ... ... ... ... ... ... Petroleum spirit (sp. gr. 0-710) ... Pure Ceresin (m.pt. 65-70 C.). Grms. per Cent. 0.056 0.016 0.100 1.9716 1.948 1-276 0.784 0.028 0.592 1.416 Paraffin Wax (m.pt. 53.7' C.). Grms. per Cent. 0.108 0.004 0.496 19,072 11 ~784 5,332 4.540 0.120 1.920 5,940 The critical temperature of solution is best estimated in 96.5 per cent. alcohol, and a table is given showing that the results obtained with mixtures of the two waxes are in close agreement with the calculated values.The turbidity tempera- tures given by d C.C. of the melted sample in 4 C.C. of the solvent in a tube 7 to 8 cm.60 ABSTRACTS O F CHEMICAL PAPERS Cd".l tetra- chloride. 42.1 23.5 in length by I cm. in diameter also afford valuable indications, as is shown in the following results in " C., obtained with the same samples of waxes : C11lOl.O- form, Benzene. Toluene. Xylene. 41.8 47.4 41 46.2 24.9 24.7 24.5 26.4 Amyl Alcohol. Carboil phide. Petro- leum Spirit (Sp. g-. 0*6886). Petro- leum Spirit (Sp. gr. 0'8725). I Ceresin . . , Paraffin Wax ... 28.8 29.8 45*1 I 51'3 66.4 40.3 51 14.8 I n most cases benzene (boiling-point 80.5" C.) will be found the most satisfactory solvent for this test, and it may even be used to eflect a partial separation of ceresin from paraffin wax.The general physical characters of certain typical paraffin waxes and ceresin are summarised in the following table : I'urbidity Tempera- ture in Benzene. Wax. Solu.bilitj in Carbon bisul- phide a t 15" C. I "C. Parafin 3 RB ... ... ,, from Schist 3 R 9 , ,, ,, 4R Ceresin .. ... America 53.7 Autun 42.1 Autun 46.5 Galicia 68.7 Critical Tempera- Refractive Index- ture of Solution 1.4280 1.4238 1.4246 1.4352 I I "C. 14185 148 1.4152 136.5 1.4161 141 1-4268 172.5 O c. 24.7 - - 47.4 Grms. per Cent. 19.07 38-68 34.65 1.97 Chemical Examination of Calabar Beans. A. H. Salway. c. &4. Ah!! (J. Chem. SOC., 1911, 99, 2148-2159.)-The ripe seed of Physostigma venenosum contains, in addition to the alkaloid physostigmine or eserine, some new substances which the author describes.He obtained two iuterconvertible modifications of physostigmine itself, C,,H,,O,N,, which appears to be dimorphous, one melting at 86" to 87" C., and the other at 105" to 106" C. The total amount separated amounted to 0-179 per cent. of the bean. Physovenine, Cl4Hl8OSN2, a new alkaloid, melts at 123" C., and has, like the previous substance, a powerful myotic effect on the pupil of the eye. Another alkaloid eseramine melts at 245" C. Calaberol, C,,H,,O,, a new dihydric alcohol, melts at 245" C. Trifolianol, C2,HQB04, is a dihydric alcohol previously isolated from red clover flowers. Stigmasterol, C,,H,,O, and sitosterol, C27H4,0, were obtained, andORGANIC ANALYSIS 61 Optical rotation in 100 mm. tube a t 21" c. ... ... Total alcohols, per cent... . ... Geraniol, per cent. C i,t r o n e l l a l , per cent. ... Volume of.80 per cent. alcohol pro- ducing clear so- lution ... ... in addition glycerides of behenic, stearic, palmitic, oleic, and linolic acids, and a sugar yielding d-phenylglucosaxone (melting-point 205" C.). H. F. E. H. - 3" 7' 51-6 27 -6 24.0 1 Aromatic Grass Oils. Part I. (Bull. Imp. Inst., 1911, 9, 240-253.)-These volatile oils are derived from members of the genera Cymbopogon, Andropogon, and retzveria, (Nat. Ord. Graminacea), and the chief are citronella, lemon grass, p&lmarosa, and vetiver oils. The ' 6 total alcohols " were calculated from the acetylated oil, and the amount of geraniol recorded was found by the phthallic anhydride method, the citronella1 being the difference between these two amounts.Three kinds of grass yield oils of the citronella type: (1) The wild mana grass; (2) the cultivated maha-pengiri grass ; and (3) lena-batu grass : Mana Grass Oils. I Oils from Cynzbopogon nardus, var. Li.nnc;ei (typicus). Maha- narm- pengiri Oil. T Yield of oil, per Sp. gr. 15" ,..I 0.920 15" C. Heen- naran- pengiri Oil. 0.200 0.913 I-2" 35' 43 *5 24.6 18'9 1 *3 10 :( Small- Leave! an a h s s Oil. 0.220 0.906 t3" 7' 57.0 34.4 22-6 1 10 "Verv Broad- Leaved Mana h s s Oil 0.170 0.926 t 1" 31' 48.7 25.8 22.9 1 10 Oils from Cynabopogon nardus, var. convertiJlorus. ' I Glau- Leave!; Mana Grass Oil. cous- 0,450 0.913 t12" 12' 465 29.3 17-2 1 10 (Whi - 3temm:d Mana bass Oil. 0.240 0.908 +lo 27' 54.8 30.2 24 -6 1 10 I ( Red- ItemniEd Mana frass Oil.0.160 0.929 t6" 19' 39'1 19.4 19. 1 10 Lena- Batu, Cpmbo- pogon nardus (Rendle, Lena- Batu). 0.420 0.913 -12" 26 57.8 31.5 26 -3 1 Maha- Pengiri, C'ymbo- pogon wintvri- anus (Jowitt). 0-500 0.890 -2" 45' 79.0 325 46 *5 1'2 Remains clear vith ten rolumes H. F. E. H. New Philippine Essential Oils. B. T. Brooks. (Philippine J. Science, 1911, 6, 333-351,)-0il of Nichelia Champaca (L) and of Nichzelia Longi,folia (Bl) (ANALYST, 1912, 28). Oil of Toddalia Asiatica (L.) Kurz (T. Aculeata Pers.).-The leaves of this species yield 0.08 per cent. of oil, of sp. gr. 0.9059 at 30" c., and [ n ] D 30" c. = 1.4620. It consists chiefly of linalol, together with about 18 per cent. of a volatile crystalline compound of camphoraceous odour melting a t 97" C. Oil of Clausena Anisurn-Olerts (BZ.) Nerr.-The oil from the fresh leaves (1.2 per cent.) has the following constants : Sp.gr. at 30" C., 0.963 ; [ n ] ~ 300 0. = 1.5235 ;62 ABSTRACTS OF CHEMICAL PAPERS saponification number, 3.6. No optical activity. Ninety-one per cent. distils between 212' to 214" C., and consists of methyl-chavicol. Clausena and rosemary are used in the preparation of aromatic liquors. The oil from Limnophila species (Scrophzdariaces) has a sp. gr. of 0,850, indicating a high proportion of terpenes. Citrus 0iZs.-Philippine orange-peel oil is of the usual character : [nID 300 c, = 1.4700 ; [a], 30' c., 90'95 ; ester number, 8.0 ; limonene, about 92 per cent, The freshly-pressed oil deposits about 0-3 per cent. of a crystalline stearoptene. Citrus Decumana.-The oil of the leaves of this species, which yields the well- known grape fruit, is present to the extent of 1.7 per cent., and has sp.gr. at 30' C., 0.870 ; ester number, 10 ; [ a ] D 300 c., 22O.9 ; [ n ] ~ 30. C. = 1.4644. It is miscible with 70 per cent. alcohol. The oil contains 25 per cent. dipentene, 15. per cent. linalol, and aldehydes in small quantity (? citral). The oil from C. hpstrilr: (0.08 per cent.) has sp. gr. at 30" C., 0.915 ; [ n ] D 30" c. = 1.4650 ; [ a ] ~ 3 0 0 , ~ . = - lo"% ; saponification number, 50.2. A. R. T. Reaction for Detecting Sesame Oil in Other Oils. Utz. (Chem. Rev. Fett- u.. Ham-Ind., 1911, 18, 292-293.)-Guarneri's test for sesame oil (Chem. Zentralbl., 1909, II., 869) consists in treating the sample with a few drops of an ethereal solution of hydrogen peroxide and a little nitric acid of sp.gr. 1.4, when a blue coloration should be obtained in the presence of sesame oil. The author describes a series of systematic tests made upon different oils and fats, from which he concludes that the colours obtained in the case of mixtures are not sufficiently distinctive, and that the reaction is not sensitive enough. The Baudouin test and Soltsien's tin chloride reaction are much more reliable and sensitive than Guarneri's reaction. C. A. M. Estimation of Phenol and p-Cresol in the Presence of Each Other. H. Ditz and F. Bardaeh. (Biochem. Zeitsch., 1911,37, 272-312.)-Results of a series of investigations are given with the object of confirming the accuracy of the method proposed some years since by Dite and Cedivoda (ANALYST, 1900, 25, 74).The method is reliable, provided that the prescribed procedure be followed, and is stated to be more trustworthy than that described by Siegfried and Zimmermann (ANALYST, 1911,36, 79). w. P. s. New Method for Determining the Melting-Point of Pitch. H. F. French. (J. Id. Eng. Chem., 1911,3,907-910.)-The method consists in heating a suspension of the pulverised material in a liquid until it coagulates. The liquid is heated by the passage of an electric current in an Erlenmeyer flask, which is rotated during the period of observation. The electrodes are ?- inch copper rods encased in rubber tubes and tipped with lead at the bottom; these are bound together with a thermometer. A 220-volt direct current circuit is used, and the electrolyte is dilute sulphuric acid standardised so that a current of 2.2 amperes passes at 25" C., whilst the flask is rotated.The correct grinding of the material is of extreme importance : 20 grms. of pitch are ground until the powder passes through a 40-mesh sieve of No. 32 wire,ORGANIC ANALYSIS 63 Nitro- gen, per Cent. having holes 0.0137 inch in size. Two grms. of the freshly-ground pitch are placed in the flask with 50 C.C. of the electrolyte and thoroughly shaken; the electrodes and thermometer are introduced and fixed parallel to one of the sides of the flask, which is then rotated at a high speed whilst the current is passed. When the suspended pitch coagulates to a distinct clot the current is switched off and the temperature noted.It is important that the pitch should not be kept longer than an hour or so after grinding, as the melting-point rises considerably on keeping. J. F. B. Number of Lbs. Per Bushel. Soot : Its Character and Composition. J. B. Cohen and A. G. Ruston. J. Xoc. Chem. Ind., 1911, 30, 1360-1364.)-The character of coal, method of combus- tion, and distance from place of combustion, all influence the composition of soot. The table shows the main differences observed in domestic and boiler samples of soot : - 1.21 0.11 2-32 4.11 6.89 Boiler, base ... ... ,, top ... ... ... Brass foundry, liquid fuel, base ... ... ... Brass foundry, liquid fuel, top ... ... ... Domestic, kitchen ... ,, room 5 feet up 35.8 34.3 63 3 40.1 22.0 16.5 Ash, Per Cent. 75.0 62.0 82.0 31.4 17.8 5.1 Zarbon, Per Cent.16.7 27.0 11.4 47.7 52.3 36-5 Tar, l’er Cent. 0.09 1-66 1-02 10.62 12.5 $4.9 The lighter and more bulky the soot, the E Value per Ton calcu- lated from Nitrogen. & s. d. 0 1 4 6 0 1 2 1 7 0 2 9 4 4 2 8 - Acidity, Per Cent. 1.33 0.56 - 0.65 0.28 0.92 gher, as a rule, is the nitrogen content, and it is advisable to buy by the bushel rather than by weight. The purchaser should demand that there be at least 4 bushels to the hundredweight. The average loss of coal in the form of soot is 6 per cent. in the case of domestic consumption and 0.5 per cent. for factories. The average deposit of soot over the City of Leeds is 220 tons per square mile per annum, the amount of tar varying from 4 to 110 hundredweight per square mile per &mum according to locality.The adverse effect of soot in the air on the growth and development of plants is very marked, the assimilating power of leaves having been found to fall from standard of 100, two and a half miles from the city, to 42 and even 12 in the University and the city itself respectively. The weight of lettuce crops was reduced from 140 to 44 over the same area. The acidity of soot is such that the corrosion of rails is six timss as great in towns as in the country, this acidity having a very injurious effect on soil bacteria, and therefore on the fertility of town soils, when present in excessive amounts, H. F. E. H. New Proeess for the Estimation of Sugars. F. von Fillinger. (Zeitsch. Untersuch. Nahr. Genussm., 1911, 22, 605-607.)-For the estimation of reducing64 ABSTRACTS OF CHEMICAL PAPERS sugars in such substance as blood, etc., the author deszribes a process which is a, combination of Bang’s and Pavy’s methods, The following solutions are required : (1) Potassium thiocyanate, 250 grms.; potassium carbonate, 250 grms. ; and potassium hydrogen carbonate, 25 grms., per litre. (‘2) Crystallised copper sulphate, 4278 grms. per litre. (3) Potassium thiocyanate, 200 grms. ; potassium carbonate, 250 grms. ; potassium hydrogen carbonate, 50 grms. ; and crystallised copper sulphate, 1042 grms., per libre. The sugar solution under examination should contain approximatoly 0.1 per cent. of reducing sugars ; in the case of solutions of unknown concentration, a preliminary estimation is made by boiling small definite amounts for two minutes with quantities of 10 C.C. of solution (3).The amount of sugar solution which just decolorises the 10 C.C. of reagent solution contains 0.01 grm. of sugar, and the strength of the solution is adjusted accordingly to make it contain 0.1 per cent. of sugar. For the actual estimation 20 C.C. each of solutions (1) and (2) are placed in a, 3ask, and the flask is closed with a rubber stopper, through which passes the nozzle of a burette containing the sugar solution. A side-tube on the neck of the flask is connected by means of a T-piece with two small wash-bottles containing alkaline pyrogallol solution; the tubes in these wash-bottles are so arranged that the air leaving the flask must pass through one of the bottles, whilst air entering the flask passes through the other. The contents of the flask are now boiled until all air has been expelled from the flask, and the sugar solution is then run in graduallyuntil the blue colour has Lccn discharged, the contents of the flask being kept at a boiling tempera- ture meanwhile. The percentage quantity of sugar is found by dividing 1 by the number of C.C. of sugar solution used, For the estimation of sugar in blood or other fluids containing proteins it is recommended that the latter be removed by treatmont with ferric hydroxide ; from 3 to 4 grms, of Godiuni chloride may slso be added to the 40 C.C. of mixed reagent solutions in order to rendx the results more concordaut. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700058

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

64 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Estimation of Antimony in Red Rubber Goods. W. Schmitz. (Gummi- Zeit., 1911, 25, 1928-1930 ; through Chem. ZentruZbZ., 1911, II., 1710.)-Three grms. of the finelyrasped rubber are treated in a Kjeldahl flask with 40 to 45 C.C. of strong sulphuric acid. A small quantity of mercury or mercury salt is added, and a piece of paraffin wax about the size of a pea. The mixture is heated until the rubber is dissolved and the black liquid begins to clear ; 2 to 4 grms. of potassium sulphate are then added, and the heating is continued until a colourless liquid is obtained. After cooling, 1 to 2 grms. of potassium metabisulphite are added, and an excess of tartaric acid ; the liquid is diluted sufficiently to prevent the charring of the tartaric acid, and boiled until the odour of sulphur dioxide has disappeared. A few C.C.of dilute hydrochloric acid are added, the liquid is diluted to 200 c.c., filtered through a dry filter, and 195 C.C. are titrated either with iodine and thiosulphate or, more simply, with potassium brornate, the latter titration being made in acid solution. The above procedure gives accurate results, and is far simpler than the usual gravi- metric method for the estimation of antimony. Decomposition of the rubber byINORGANIC ANALYSIS 65 means of fuming nitric acid in presence of sulphuric acid gives good results, but the method recommended by Frank and Birkner (ANALYST, 1910, 35, 131), in which ammonium persulphate and nitric acid are employed, is difficult in operation. J.F. B. Estimation of Antimony in Red Rubber aoods. W. Schmitz. (Gummi- Zeit., 1911, 25, 2002-2003 ; through Clzem. Zentralbl., 1911, II., 171 1.)-The method recommended by the author (see preceding abstract) is preferable to that of Frank and Birkner (ANALYST, 1910, 36, 131), because it can be performed on a relatively large quantity of material (2 to 4 grms.) and because in the latter method the rubber tends to ignite unless the nitric acid be suitably diluted. The oxidation of the rubber by sulphuric acid can, however, be accelerated by the use of ammonium persulphate. When the rubber is completely dissolved and the black liquid begins to clear, solid ammonium persulphate is added to the contents of the flask until the liquid becomes colourless. If small particles of carbon remain floating in the clear liquid, heating must be continued and more persulphate added.The liquid is then diluted and boiled for a long time in order to destroy the residual persulphate. When using this method, the titration with iodine is more suitable than that with potassium bromate, since the persulphate sometimes yields a liquid of yellow colour. The author’s method possesses the advantage of being extremely rapid (total time not more than two hours), and of avoiding the presence of nitric acid and oxides of nitrogen, which would interfere with the titration. J. F. B. Detection, Separation, and Estimation, of Arsenie and Antimony. G. Bressanin. (Boll. ChZirn. Farm., 1911, 50, 691-694 ; through Chem. Zentralbl., 1911, II., 1964.)-The method of Blattner and Brasseur (ANALYST, 1904, 29, 167) for the estimation of small quantities of arsenic in hydrochloric acid and sulphuric acid yields inexact results : 2 per cent.low, for example, in concentrated hydrochloric acid. With sulphuric acid (sp. gr. 1-45), even if it contained one-third hydrochloric acid, accurate results were obtained. Washing the precipitate of arsenious iodide with hydrochloric acid containing potassium iodide involves the danger of liberating iodine ; and 2-5 C.C. or less of the potassium iodide solution should be used instead of the 5 C.C. prescribed. To determine the arsenic in hydrochloric acid, the author mixes 1 part of the acid with 2 of sulphuric acid (sp. gr. 1.45). I n sulphuric acid free from lead or tin, the precipitation is carried out without the addition of hydro- chloric acid.Commercial sulphuric acid is first brought to a sp. gr. of 1.45, and one-third of hydrochloric acid added ; nitroso compounds, if present, are destroyed with urea. For washing, a mixture of 4 parts of sulphuric acid (sp. gr. 1-45) and 1 part of hydrochloric acid is used. The sulphuric acid under examination may be over a sp. gr. of 1.45--e.g., 1.52. Thus modified, the method gave good results. Antimonious iodide was found to be soluble in concentrated hydrochloric acid, and the method, for antimony, is thus confined to estimations in sulphuric acid. The reactions may be followed under the microscope: the yellow hexagonal plates of arsenious iodide are easily distinguished from the purple-red antimony iodide crystals of similar shape, To determine arsenic and antimony occurring together, the sample is66 ABSTRACTS OF CHEMICAL PAPERS dissolved in sulphuric acid (sp.gr. 162) to a standard volume, the antimony iodide and arsenious iodide precipitated in an aliquot part, without the addition of hydro- chloric acid, and the arsenic and antimony determined together by titration. The precipitate from a second portion to which one-third hydrochloric acid had been added is washed three times in the usual manner, dissolved, neutralised, and the arsenious iodide titrated ; the antimony iodide is found by difference. Arsenates and antimonates are estimated similarly. 0. E. M. Detection and Estimation of Arsenic in Organic Compounds. G. Bres- sanin. (Boll.Chim. Farm., 1911, 50, 727-730 ; through Chem. Zentralbl., 1911, II., 1695.)-The author applied the method (see preceding abstract) to the estimation of arsenic in sodium cacodylate, arrhenal, atoxyl, and salvarsan. In sulphuric acid of sp. gr. 1.45, these compounds, except salvarsan, even in dilute solution, gave characteristic, various - coloured precipitates with potassium iodide. The cacodylate always gave the smell of cacodyl. For estimation, 0.2 to 0.4 grm. of the substance was heated carefully in a long-necked flask for two hours with 10 C.C. concentrated sulphuric acid. Sulphur dioxide was expelled by a strong current of air, the contents of the flask transferred, with repeated washings with sulphuric acid (1.45 sp. gr.), to a 100 C.C. flask, and made up to the mark with the same acid.The arsenic was determined as described (see preceding abstract) in an aliquot portion. Results for sodium cacodylate, arrhenal, atoxyl, and salvarsan, agreed well with the theory. Salvarsan, unlike other organic arsenic compounds, in solution in sulphuric acid, gives no precipitate with potassium iodide. I t reacts violently with sulphuric acid of sp. gr. 1-84 with evolution of sulphur dioxide; if then diluted with sulphuric acid of 1.45 sp. gr., it gives a precipitate with potassium iodide. 0. E. M. Determination of Copper : A Modification of the Iodine Method. C. Kendall. (J. Amer. Chem. SOC., 1911, 33, 1947.)--The modification is intended to make the iodide method as rapid as the less accurate, but hitherto more con- venient, cyanide method.The removal of the nitrous acid formed by solution of the copper, as metal, oxide, or sulphide, is effected by means of sodium hypochlorite, instead of by evaporation to dryness, or by the use of bromine. The chlorine liberated is converted into chlorophenol, which is not ionised. If the sample is metallic copper, 200 to 300 mgrms. are dissolved in 5 to 10 C.C. of 50 per cent. nitric acid; if cuprous oxide, it is collected on asbestos in a Gooch crucible, and thence dissolved with 10 to 15 C.C. of 30 per cent. nitric acid; if cuprous sulphide, it is collected on a *-inch layer of asbestos in a Gooch crucible, the crucible with its contents boiled in a 50 C.C. beaker with 10 C.C. of 50 per cent. nitric acid until solution is complete, and solution and asbestos washed into a conical flask; if a solution of a copper salt, a quantity containing 200 to 300 mgrms.of copper is taken. To the solution in a 300 C.C. conical flask, its volume being between 50 and 60 c.c., its acidity equal to 4 or 5 C.C. concentrated nitric acid, and its temperature not above 25' C., are added 5 C.C. of hypochlorite solution made by boiling together 112 grms: calcium hypochlorite having 35 per cent. or more available chlorine, 100 grms. anhydrous sodium carbonate, and 1,200 C.C. water, filtering, and adjust-INORGANIC ANALYSIS 67 ing the hypochlorite solution until 5 C.C. are equivalent to 30 C.C. & thiosulphate. A change of colour from a clear blue to a greenish tint, or the evolution of chlorine, shows that enough hypochlorite solution has been added.At the end of two minutes, 10 C.C. of colourless 5 per cent. phenol are rapidly added, chlorine above the liquid blown off, the flask washed down with water, and 20 per cent. sodium hydroxide run in until a, very slight precipitate forms. This is just dissolved by the addition of 50 per cent. acetic acid, followed by 10 C.C. of potassium iodide solution containing 30 grms. per 100 C.C. The titration is made with thiosulphate (1 C.C. = 6 mgrms. Cu) until the liquid has a light straw colour. After addition of starch solution the titration is finished, thiosulphate 1 C.C. of which is equivalent to 1 mgrm. copper being used if great accuracy is required. The results appended show a percentage error ranging from - 0.10 to + 0.15. 0. E. M.Method for the Estimation of Selenium in Sulphur and Pyrites. P. Klason. (Chem. Zeit., 1911, 35, 1345.)-Sulphite lye containing 0.5 mgrm. selenium per litre is useless. The author estimates this small quantity by means of hydriodic acid : the selenious acid sets free iodine, which is detected by its action on starch, As a control, sulphur to which a known quantity of selenium had been added was burnt in a tube. Until all the sulphur was burnt, no oxidation of selenium took place; then, in oxygen, selenium dioxide was sublimed, and it was found that 0.1 mgrm. could be detected with certainty. Pyrites was treated similarly, but in a quartz tube. Sicilian sulphur was found to contain about 0.9 grm. ; Japanese, 1 to 20 grms. ; and Falun pyrites, usually 10, but sometimes 30 or 40 grms.selenium per ton. The author's method allows 92 per cent. of the selenium in sulphite liquor containing only 0.25 mgrm. selenium per litre to be determined. 0. E. M. Volumetric Estimation of Sulphur in Iron and Steel. T. G. Elliot. (Chem. News, l911,104,298.)-A mixture of 5 grms. of the sample with 0.25 grm. finely powdered anhydrous potassium ferrocyanide is wrapped in one 11 cm. filter-paper if the sample is a graphitic iron, in two if it is a steel or white iron, annealed in a covered porcelain crucible for twenty minutes in a closed muffle at 750" to 850" C., and allowed to cool slowly outside the muffle. If the paper is burnt away from above the drillings, the annealing has been at too high a temperature or too long, and the results will be low.The drillings are emptied into a glass mortar, loosened with a pestle, and transferred to the evolution flask, without touching its neck or sides. With the flask is connected a condensing-tube, 6 inches by 1 inch, containing 2 inches of water and standing in cold water, and with this in turn a flask containing 60 C.C. of cadmium chloride solution, made by dissolving 20 grms. of cadmium chloride in water containing a few drops of hydrochloric acid, adding ammonia until the precipitate formed dissolves, acetic acid to acidity and 20 C.C. in excess, and water to 2 litres. To the sample are now added 50 C.C. of concentrated hydrochloric acid, and heat is applied until the frothing shows that solution is well begun. The flame is lowered until the stream of gas slackens, then raised, and the liquid gently boiled until appreciable evolution of gas ceases. Excess of standard iodine solution is run into A safety-flask containing more cadmium solution is attached,68 ABSTRACTS OF CHEMICAL PAPERS the absorption-flask-usually nothing is found in the safety-flask-then about 10 C.C. of 1 in 2 hydrochloric acid, and the sulphide dissolved by shaking. The excess of iodine is titrated back with standard sodium thiosulphate. Displacement of the air by CO, is unnecessary in works practice. Correction may be made for any sulphur introduced as sulphates in the paper or ferrocyanide from the difference in sulphur found in samples of the same pure iron with and without annealing. The standard solutions used (1 c.c.= 0.005 per cent. sulphur on a 5-grm. sample) are standardised against a steel or iron of sulphur-content determined by the "aqua regia" or Bamber's method. An iron containing 0.2 per cent. of titanium and 0.080 per cent. sulphur (gravimetric) gave 0.018 unannealed, 0.066 after annealing at 800" C., and 0.076 per cent. after annealing at 950" C. for five minutes and above 790" C. for fifteen minutes. This suggests that with proper preliminary treatment the evolution process may be applied even to titanium pigs. 0. E. M.

ISSN:0003-2654    

DOI:10.1039/AN9123700064

出版商:RSC    

年代:1912

数据来源: RSC

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68 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. The Quantitative Manipulation of Small Quantities of Preeipitates, J. Donau. (Monatsh. fiir Chem., 1911, 32, 1115-1139.)-The author describes the apparatus and methods adopted in carrying out his improved method of quantitative microchemical analysis, and gives details of procedure in the case of twenty-six typical gravimetric estimations. The Nernst microbalance has been improved by constructing the beam and pointer in a single piece, with a glass counterpoise fused on to the beam at the end near the pointer. At the other end of the beam a piece of silver wire is fused into the glass, from which the filter-pan is suspended by means of a strand of very fine Wollaston wire, ending in a, hook below. The whole balance is enclosed in an air-tight case sealed with paraffin wax to exclude moisture; the atmosphere inside is kept dry by means of quicklime, and access is obtained to the pan-hook by a, circular hole 3 cm.in diameter, closed by a glass slide which is smeared with vaseline. For collecting the precipitates, the asbestos filter-bed (ANALYST, 1911, 36, 180) has been replaced to great advantage by one of spongy plateinurn. The filter-pan is formed out of a circular piece of thin platinum-foil 10 to 12 mm. in diameter, perforated at the bottom and provided with a wire loop for hanging on the balance. Spongy platinum is deposited on the perforated bottom of the pan, and the deposit is covered with a smaller platinum-foil tray, also perforated; in this way most of the precipitate, after weighing, may be lifted out of the filter bodily, leaving only a little to be dissolved out by chemical means.The author describes an ingenious arrangement for producing and manipulating the precipitates. It consists of a short glass tube 1 cm. wide, open at the top, and terminating in a narrow tube at the bottom, this being closed by a piece of glass rod attached by a rubber tube. The substance is dissolved in this vessel, the precipi- tating reagent is added, the whole being heated if necessary. The upper mouth of the precipitating vessel is then closed with a cork carrying a glass bulb-tube which has just been heated. On cautiously opening the lower end, air is sucked up the capillary, and the bubbles stir the precipitate. Similarly, by applying a hot glass od to this bulb-tube the liquid and precipitate can be expelled down the capillaryAPPARATUS, ETC.69 into the filter. vessel is washed out by similar procedure described above. in .bhe paper. A bell-jar is placed between the pump and filter. The precipitating Full details are given J. F. €3. Apparatus for Extracting Liquids with Immiscible Solvents, and for Measurement of Evolved Gases. R. F. Bacon and P. B. Dunbar. (U.S. Bureau of Chemistry Circular ; through Chem. Eng., 1911, 14, 430-431.)-Continzious Liquid Extraction.-As shown in Fig. 1, the apparatus consists of a flask, u, of glass tubing, of 2 inches in diameter (& inch thickness) and 20.5 inches in length, and enlarged to about 3 inches at its lower end; an extraction thimble, b, an ordinary test-tube of 18 inches diameter and of 100 C.C.capacity when filled to 16 inches of the top, having at a distance of a 4 inch from the top and on opposite sides two holes about 4 inch diameter; a Gooch crucible funnel, c, 8.5 inches long, but longer if dense liquids are to be extracted, with the lower end of the stem ground at an angle of 45 degrees; and a condenser, d, hanging loosely in the flask. About 100 to 150 C.C. of ether are poured into the flask, and 100 C.C. of the liquid to be extracted is placed in the test-tube; the funnel is inserted into this tube and suspended in the flask, about 3 inches above the bottom, with a copper wire passing through the holes in the tube and hooked over the rim of the flask neck. The condenser is placed in the top of the flask, and condensed ether drops from the condenser into the funnel, and is carried down to the bottom of the tube, whence it passes through the liquid, and overflows at the top.The efficiency of the extractor may be increased by using a glass spiral attached to the stem of the funnel (Kampf, Chern. Zeit., 1910, 34, 1365). Measurement of Evolved Gases.-The solid or liquid substance to be acted on is placed in the FIG. 1. FIG. 2. reaction chamber, b (Fig. a), and with the stopcock, x, open, the liquid in the eudiometer-tube, d, is brought to zero by raising or lowering the levelling- tube, e. The reagent is placed in u, with the stopcock closed, and, after lowering the levelling-tube, the stopcock is opened and a known quantity of reagent mixed with the material to be acted on.The reaction-chamber, b, may be heated if required by means of a coil wrapped round it. After cooling to room temperature, the increased volume of the air and gas in the apparatus is read off as usual, deducting the volume of the added reagent. The absorption-tube, c, is filled with beads, and70 ABSTRACTS OF CHEMICAL PAPERS is sealed on to the endiometer, and fits into the reaction-chamber, b, by means of a, ground joint at f. The apparatus is suitable for the estimation of citric acid by Spica’s method, and for amino-acids by the method of Van Slyke. A. R. T. Notes on Thermostats, Shaking and Stirring Apparatus, ete. A. C. Cumming. (Chem. News, 1911, 104, 307-309.)-A thermostat is best made of copper, and should be of such size that the introduction of the experimental apparatus does not materially alter the temperature of the contained water.A constant level is maintained in the usual way. The liquid contained in the regulator attached to the thermostat should have a, low specific heat, high co-efficient of expansion, and low density. Mercury has a very low specific heat (0-03), but its FIG. 1. FIG. 2. great density necessitates the use of thick-walled apparatus. Benzene, toluene, alcohol, ether, carbon tetrachloride, etc., may be used, the one having the lowest density being the most efficient. A spiral to give a large surface of exposed liquid is commonly employed, thus giving a sensitive regulator (Lowry, J. Chem. SOC., 1905, 87, 1030), and this spiral is preferably made of metal. A satisfactory con- nection is made with rubber if a waiier-trap is introduced between the mercury and the organic liquid, so that the water layer covers the junction between the metal and glass.Of the forms of apparatus for cutting off the gas-supply, those of W. H. Green (Chem. News, 1908, 98, 49) and T. S. Patterson (ANALYST, 1902, 27, 234) areAPPARATUS, ETC. 71 satisfactory. A novel method of altering the amount of mercury in the regulator, to produce altered temperature, has been described by A. Slator (ANALYST, 1911, 36, 127). Two forms of electrically-controlled regulator have been devised by C . Fraser, and have been found to be reliable. I n the first (see Fig. l), a metal plunger, P, floats on the surface of the mercury. This carries a curved platinum wire, c, at the end of a rod, and contact is made when C comes into contact with C', the point of contact being covered with platinum.The vulcanite plug Vserves to insulate C' and its connections. The adjustment is made as usual, finally by raising or lowering C'by means of the brass screw, Fraser regards the form shown in the next figure as an improvement on the latter. Contact between two platinum terminals (C, and Cz) is broken when the rise of the plunger lifts C,. A side-to-side movement is avoided by the garnet jewel setting ( J ) in the vulcanite ring V. The regulating screw serves for fine adjustment, the rough alteration being made by increasing or reducing the amount of mercury in the regulator. I n connection with shaking apparatus, J. Knox uses a driving band of brass wire wound in a narrow close spiral. This is advantageous for bands to be used under water, owing to the disintegrating action on leather and gut. For stirring apparatus the author uses the glass- angle stirrer shown in the illustration. The side-tube is 2 inches long, and the vertical tube of such length that it ends about 1 inch from the bottom of the bath when the side-tube is 2 inches below the surface. A deep thermostat may be stirred by blowing a stream of air through the water, the bubbles of air ascending through a wide tube open at both ends. The temperature in any part of the bath is thus kept at not more than 0.1' variation from other parts. More vigorous stirring by mechanical means is, however, necessary for closer constancy of temperature. A. R. T. t B C t i * & i t f i Bra SI Collar FIG. 3.

ISSN:0003-2654    

DOI:10.1039/AN9123700068

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

APPARATUS, ETC. 71 REPORTS. On the Work of Inspectors of Foods. A. W. J. Macfadden. (Appendix A, No. 8, from the Annual Report of the Medical Officer of the Local Government Board for 1910-ll.)-The Report deals with work in special relation to the Public Health (Regulations as to Food) Act, 1907, meat inspection, food-poisoning, work in special relation to the Sale of Food and Drugs Acts, Conference on Methods of Analysis, Paris, 1910, and with foreign and colonial food legislation. Special inquiries were made in regard to the chemical treatment of flour, and the purity of baking-powders and self-raising flours, and reports dealing with these questions have been issued (cj. ANALYST, 1911, 36, 254, 255). A report was also issued on the occurrence of parasitic nodules in meat exported from Australia (cf.ANALYST, 1911,36,129). In72 REPORTS order to deal more effectively with this condition in Australia, the Commonwealth Government have taken over the control of the inspection of meat for export, which was carried out previously by the various States. Several cases of illness attributed to the consumption of meat foods containing bacterial poisons occurred during the year ; reference is made to the difficulty which is generally met with, of obtaining at a sufficiently early date information of the kind necessary for elucidating the causes of the poisoning. Representations and reports received by the Board on matters relating to local administration of the Sale of Food and Drugs Acts entailed special inquiries or interviews.Particular notice is directed to the unsuitable procedure adopted in certain districts with regard to the taking of samples. Among other defects may be noted the practice of sampling officers asking for ‘( new milk ” when purchasing milk samples for analysis ; this simply supplies a gratuitous warning to the vendor to be on his guard. The Sale of Milk Regulations refer to ‘‘ milk,” and the use of the term ‘‘ new milk ” is unnecessary. Considerable attention has been given by local euthorities to the question of lard and lard substitutes. Added water was reported to be present in a few of the samples of lard, and in each of these instances the lard was also found to be adulter- ated with foreign fat. One sample of “ compounded lard,” purchased in London, contained 17.8 per cent. of water.All the samples of imported margarine taken by Customs officers during the year were examined for the presence of paraffin, and one sample imported from Holland was found to contain 3.4 per cent. of solid paraffin. Although the Board have no reason to consider that this form of adulteration is common, they would be glad to receive information as to the results, .positive or negative, of any examination for the presence of parafin which may be made by the public analyst when samples of margarine and lard are submitted to him. Rules for the unification of the expression of analytical results, formulated by the International Conference, Paris, 1910, are printed in an addendum to the Report (cj. ANALYST, 1911, 36, 536). w. P. s. The Conneetieut Agricultural Experiment Station.(Thirty-third and Thirty-fourth Reports, 1909 and 1910.)-This volume of over 800 pages forms Public Document No. 24 of the State of Connecticut, and is the biennial report for the two years ended October 31, 1910. Almost every department of agricultural activity is embraced, and the sections dealing with plant diseases and entomology are well pro- vided with excellent illustrations and photographs. A very full report on commercial fertilisers, usefully classified, is followed by sections in which a total of 1,630 samples of foods and drugs are summarised, exactly 25 per cent. of these having been found to be adulterated or below standard. The methods of analysis employed in the examination of many of the materials dealt with are described.Illegal labelling and misbranding are carefully looked for, as they constitute offences against the State laws. An interesting report is that dealing with the analyses of some fifty named proprietary breakfast foods. It is curious to note that no single examination of cocoa or chocolate appears in the whole volume, and since the practice of adulter- ating cocoa with ground shell is known to exist, the omission is unfortunate.REVIEWS 73 Commercial feeding-stuffs are fully dealt with, useful tables being appended of their composition, digestibility, and price. A very full account of canned peas is a valuable feature in tbe present work ; over 100 samples are described and analysed in detail. The American public, if they choose to avail themselves of reports like the present, are clearly afforded ample information as to the most satisfactory manufac- turers to patronise for all the principal materials of domestic consumption, and the practice of publishing names in full should act as a strong inducement to sellers to provide a trustworthy and unadulterated article. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9123700071

出版商:RSC    

年代:1912

数据来源: RSC