76 THE ANALYST. ORGANIC ANALYSIS. Preparation of Pure Ethyl Alcohol. L. W. Winkler. (Berichte, 1905, xxxviii., 3612-3616 ; through Pharm. Joumn., 1905, vol. 76, 12.)-Acetaldehyde is removed from commercial absolute alcohol by allowing the sample to stand over finely-powdered silver oxide for several days, a little potassium hydroxide being also added. The amount of silver oxide required is never more than a few grams per litre, and about 1.2 grams of potassium hydroxide is sufficient to neutralize all the acetic acid resulting from the oxidation of the aldehyde. The mixture should be shaken from time to time. The water present in the alcohol is then removed by heating the latter for several hours over, and finally distilling from, metallic calciumTHE ANALYST. 77 filings, using about 20 grams of the metal per litre.The alcohol so obtained can be once more distilled from metallic calcium. The advantage in the use of calcium over sodium lies in the fact that calcium hydroxide is totally insoluble in alcohol, and therefore as long as the alcohol contains moisture a white precipitate will be formed. The author has made a number of determinations of the specific gravity of pure ethyl alcohol, and has deduced from them the following formula for calculating the specific gravity of alcohol at any temperature from 0" to 30' C. : Specific gravity 0"-30" = 0.80629 - 0*000838t - 0.0000004t~, where 0.80629 is the specific gravity of alcohol in vacuo compared with that of water at 4" C. The boiling-point of pure alcohol was found to be 78-37' C.at 760 mm. pressure. It was observed that absolute alcohol is not so hygroscopic as is commonly imagined ; 200 C.C. of absolute alcohol absorbed less than 0.1 per cent. of water after fifteen minutes' exposure to the air. w. P. s. The Determination of Traces of Benzaldehyde. H. He'rissey. (Joz~cr.12. Pharm. Chim., 1906, xxiii., 60-65.)-Phenylhydrazine reacts with benzaldehyde to form an insoluble phenylhydrazone- C,H,NH.NH, + C,H,.COH = C,H,.CH.N.NH.C,H, + H,O. The reagent used by the author consisted of 1 C.C. of freshly distilled phenylhydra- zine and 0.5 C.C. of glacial acetic acid in 100 C.C. of water. On treating an aqueous solution of benzaldehyde with an equal volume of this reagent, and allowing the mixture to stand for twenty-four hours at 15" to 20' C., there was formed an insoluble crystalline precipitate, which could be collected in a Gooch's crucible, washed with a known quantity of cold water, and dried in a vacuum over sulphuric acid until constant in weight.I t was found, however, that very faint traces of the aldehyde required a very long time for complete combination, and, on the other hand, the results were liable to be too high if the reagent was allowed to act for several days. But by heating the mixture on the boiling water-bath for twenty minutes, and then allowing the liquid to stand for twelve hours before filtration, washilig the precipitate in the Gooch's crucible with 20 C.C. of water and drying it in vacuo, excellent results were obtained, especially when the quantity of phenylhydraaone did not exceed 0.1 to 0.25 gram.C. A. M. On the Determination of Sugar with Fehling's Solution. F. P. Lavalle. (Chem. Zeit., 1906, xxx., 17.)-It is often difficult to determine the end-point of the reaction in titrating a solution of glucose, owing to the cuprous oxide subsiding but slowly, and reflecting its colour to the surface. The author obviates this by adding an excess of alkali, and thus preventing entirely the separation of the cuprous oxide. From 5 to 10 C.C. of Fehling's solution are placed in a 200 C.C. porcelain basin, together with 30 C.C. of sodium hydroxide solution (1 : 3) and 50 to 60 C.C. of water,78 THE ANALYST. and the liquid heated to incipient boiling, and then titrated with the sugar solution, the reaction being complete as soon as the last drop causes the blue colour of the Fehling's solution to disappear.Test experiments are stated to have given very satisfactory results. C. A. M. The Detection and Determination of Trehalose by Means of Trehalase. P. Harang. (Jourrt. Pharm. Chim., 1906, xxiii., 16-20.)-The method is based upon the fact that trehalose (a= + 197" 3 ) is inverted by the specific enzyme trehalase into two molecules of glucose, which will, of course, reduce Febling's solution. Thus, if a 1 per cent. aqueous solution of anhydrous trehalose giving in the polarimeter a reading of a = + 3" 57' be treated with trehalase, the liquid, after complete inversion of the hexabiose, will be found by means of Fehling's solution to contain a quantity of reducing sugar corresponding to 1.052 grams of glucose, and the deviation ( I = 2) will be + 1" 6', a, difference of 2" 51'.If, then, the difference between the rotations calculated from the amount of glucose formed under the action of the enzyme coincides with the polarimetric readings, the presence of trehalose may be inferred, and its amount may be calculated, provided that the enzymic action is complete. In order to obtain the specific enzyme trehalase the author incubates a cultiva- tion of Aspergillus niger on Raulin's fluid at 33' C. until the first signs of fructification (about twenty-four hours). The nutrient fluid is then decanted and replaced with water, and the cultivation allowed to stand at the ordinary temperature for five or six days until fructification appears, the water being renewed every twenty-four hours.The mould fungus is then pressed between filter-papers, finely divided, left for three hours in contact with a fourth of its weight of 95 per cent. alcohol, drained with the aid of a filter-pump, and finally dried in the oven at 33" C . and powdered. This prepara- tion has a strong enzymic action upon trehalose, 0.5 gram being sufficient to invert 1 gram of the sugar in 100 C.C. of water within forty-eight hours at 33" C. Before using the enzyme for the detection of trehalose in mushrooms, etc., it is necessary to eliminate substances such as glycogen, which can also be attacked by it. The fungi are twice extracted, as soon as possible after being gathered, for ten minutes with their own weight of boiling 90 per cent. alcohol, and the united extracts filtered.The filtrate is distilled under reduced pressure until the residue is only 100 C.C. (from 1 kilo of fresh mushrooms). On now adding 4 parts by volume of 80 per cent. alcohol to the residue there is an abundant precipitate, which is left to subside until the next day. The clear liquid is then decanted, and the residue mixed with a few C.C. of water, taken up with 4 parts by volume of 80 per cent. alcohol, and boiled for twenty minutes on the water-bath under a reflux condenser. It is then allowed to cool and the supernatant liquid decanted, united with the washings, and evaporated to dryness in oucuo. Finally, the residue is taken up with water saturated with thymol (100 C.C. for each 200 grams of mushrooms), and this solution treated with enzyme.C. A. M. The Charaeteristies of Certain Animal Fats. C. Schneider and S. Blumenfeld. (Chem. Zeit., 1905, xxx., 53, 54.)-The following physical and chemical values were obtained :ANIMAL. Vikare s e a l (Phoca fa- tida) Vikare seal (Phoca fa- tida) Porpoise (Pho- cans com- munis) Coot (Fulica atra) Crane (Grus cinerea) Lynx ( t y n z europczus) Glutton (Gzdo b o r e:alis) body fat Glutton (GuZo b o r e a 1 i s) kidney fat Bear (UTrsa arctos) 0.9321 0.9336 0.9334 0.9163 0.9222 0.9248 0.9153 0.9230 0,9156 FATS. 87.0 at 20" c. - 62.7 at 25" C. 62-9 at 25" C. 61.5 at 20° c. 70.0 at 20" c. 54.2 at 30" C. 45.2 at 45" c. 60.8 at 20" c. 0.48 1.08 1.2 1.66 9.33 On81 5-84 -- 50.6 188.5 189.0 224.8 192.6 191.2 190.22 193.3 193.3 191-0 191.35 193.3 111.2 87.13 75.25 110.6 54.36 50-82 80 *7 95.6 95.8 85.5 95.2 95 *7 95.8 95.4 95.8 94.5 1.55 0.96 12.1 0.35 0.13 0.43 0.12 - 0.33 FATTY ACIDS. 0,9172 - 0.9121 0-9151 0.9005 0.9412 0.9118 - 0.9347 74.1 at 20° c.- 54.3 at 25' C. 44.7 at 35" c. 40.8 at 30" C. 53.9 at 35" c. 31.9 at 45" c. 31.7 at 45O c. 43.0 at 40" C. 14.0 - - 33.5-34.5 31-0 35.5 40.0-41 *O 40*0-41*0 37.5 13.0-14 0 13.0-14-0 18.0 30.5 29.3 35.0 37.5 - 36.1 198.0 196.0 207.0 - 201.0 202 7 203.4 203.0 203.0 195.3 201.8 126.0 84.8 73.5 111.8 55.5 52.8 '76.580 THE ANALYST. The high Reichert value of the porpoise fat was due to the presence of a considerable quantity of the glycerides of valeric acid. The fat, which was derived from the body, was oily, and had a pale yellow colour. Of the other fats examined, that of the seal was a soft yellow semi-solid; the fats of the coot, crane, and lynx were soft white or light yellow semi-solid masses ; the fat of the glutton was a white, not very hard fat ; and the bear’s fat had the consistency of vaseline at 15O C.I t is pointed out that the iodine valueof the fat of the lynx is the highest yet recorded for land beasts of prey. C. A. M. Determination of the Total Organic Acids in Tobacco. J. Toth. (Ghem. Bit., 1906, xxx., 57,58.) -The method proposedis similar to the one describedpreviously by the author for the, determination of nicotine (ANALYST, 19q2, p. 12). Two grams of the dry powdered tobacco are moistened with 2.5 C.C. of 20 per cent. sulphuric acid, and then mixed with sufficient plaster of Paris to form a dry powder.This is placed in a well-corked cylinder and shaken for forty-eight hours with 100 C.C. of anhydrous ether ; 50 C.C. of the ethereal solution are then drawn off, evaporated slowly, and the residue dissolved in warm water. The solution is now titrated with $ sodium hydroxide solution, using alkanna tincture as indicator (ANALYST, 1903, p. 193), and the result calculated into anhydrous oxalic acid. In thirty-two samples of various tobaccos examined, the writer found from 3.6 to 8.7 per cent. of total organic acids (expressed as oxalic acid), and the quantity of organic acid was found to be propor- tional to the burning quality of the several tobaccos--that is, bad-burning tobaccos contained the most acid. w. P. s. Estimation of Tannin in Crude Products.A. Manea. (Chem. Zeit. Rep., 1905, xxix., 381,)-The principle of the method lies in the fact that when a certain quantity of a tannin solution is added to a mixture of a known quantity of glacial acetic acid and neutral lead acetate of known dilution, the tannin alone is pre- cipitated with the lead, whilst all other substances remain in solution. The author has obtained results which give not more than 0.5 per cent. difference in analyses of the same raw material. E. K. H. Estimation of Caoutchouc. T. Budde. (Chem. Zeit. Rep., 1905, xxix., 393.) -The process recommended, after many experiments, is as follows : A solution of bromine in carbon tetrachloride is used as a brominating liquid, iodine being added as a halogen carrier, the action being then continuous.The proportions used by the author are : 16 grams bromine (6 c.c.) and 1 gram iodine dissolved in carbon tetra- chloride and made up to 1 litre. For the estimation about 1 gram of the sample of caoutchouc is placed in a 100 C.C. flask, covered with carbon tetrachloride, and allowed to stand, with frequent shaking, until the caoutchouc has dissolved, or is evenly divided. The flask is then filled to the mark and well shaken. Ten C.C. are taken for each analysis. This is filtered, if necessary, in an Allihn’s tube and washed with about 50 C.C. CCl,. To the filtrate 50 C.C. of the brominating solution are added, when a jelly-like substance is soon precipitated. After the solution has become clear (quarter of an hour), half its (If the solution is too viscous, it must be diluted.)THE ANALYST.81 volume of alcohol is added ; the liquid is now clear yellow, and the tetrabrom-caout- chouc is transformed into the white form. I t can now be easily transferred to a weighed filter paper, washed first with a mixture of 2 parts carbon tetrachloride and 1 part alcohol, and then with pure alcohol, and dried to constant weight at 60" C. ; 456 grams of tetrabrom-caoutchouc = 136 grams of pure caoutchouc. Caoutchouc resin and oxidized caoutchoucs do not take part in the bromine reaction. The process recommends itself by its simplicity, and especially by the fsct that it give? fhe true content of pure caoutchouc. E. Ei. H. The Direct Determination of the Acetyl and Benzoyl Groups. R. Meyer and E. Hartmann. (Berichte, 1905, xxxviii., 3956.)-From 0.5 to 0.7 gram of the substance is heated with about 5 grams of pure sodium hydroxide and as small a quantity as possible of methyl alcohol which has been purified by distillation with potassium hydroxids. After about an hour the saponification is complete in the case of most acetates, and the solution is then mixed with 50 C.C. of phosphoric acid (specific gravity 1*104), and distilled in a current of steam, a little lime being placed in the vessel in which the steam is generated. In order to determine whether the distillation is complete, portions of the distillate are titrated from time to time after it is thought that the bulk of the acid has passed over. The distillation should be continued until 150 C.C. of the distillate consume not more than 1 or 2 drops of baryta solution, phenolphthalein being used as indicator. The determination of the benzoyl group is carried out in the same way, and gives equally satisfactory resul t s, C. A. M.