1134 EXPERIMENT STATION RECORD. 



New rapid method for the determination of fat in milk without the use of 

 acid, N. Gerber {Rev. Gen. Lait, 5 (1906), No. U, pp. 318-321).— In this method, 

 designated the salt method, the same apparatus is used as in the Gerber acid method, 

 but the casein is dissolved by means of an alkaline solution, the exact composition 

 of which is at present secret. Comparative determinations by the salt and acid 

 methods are reported. They show very close agreement. 



The salt method, M. Siegfeld (Molk. Ztg., JO {1906), No. 14, pp. 371-373).— The 

 salt mixture used in dissolving the casein in this new Gerber method is said to con- 

 sist of sodium chlorid, sodium hydroxid, Rochelle salt, and a small quantity of 

 coloring matter. 



A solution is made by dissolving 230 gm. of this mixture in 1 liter of water. 

 Eleven cc. of this solution, 10 cc. of milk, and 0.6 cc. of isobutylalcohol are mixed 

 in the acid butyrometer, which is then placed in a water bath at 45° C. for 3 min- 

 utes and then centrifuged for 3 minutes. The reported results by the salt method 

 are essentially the same as those by the acid method. The salt method is said to be 

 uninfluenced by the presence of formalin or potassium bichromate in the milk. 



On the importance of determining- the freezing- point in milk analysis, A. A. 

 Boxxema (Pharm. WeekbL, 43 (1906), No. IS; abs. in Per. Gen. Lait, 5 (1906), Xo. 15, 

 pp. 346, 347) . — The average freezing point of fresh cows' milk was found to be 

 —0.555° C, which was increased as much as 0.02° by allowing the milk to stand for 

 several hours or by boiling. Lactic fermentation lowered the freezing point. The 

 importance of cryoscopy in detecting adulteration of milk is discussed. 



The detection of cocoanut oil in butter, A. W. Thorp (Analyst, 31 (1906), Xo. 

 363, pp. 173-175). — The author determines the Reichert-Wollny number in the usual 

 way, then adds 110 cc. of water to the flask, and distills off a second 110 cc. and 

 titrates this with tenth normal sodium hydroxid. The insoluble volatile acids are 

 then dissolved in 100 cc. of 90 per cent alcohol slightly warmed and this is also 

 titrated with the tenth normal soda solution. 



The number of cubic centimeters of the tenth normal soda solution required in the 

 3 determinations were respectively 29.2, 3.1, and 7.6 for normal butter and 8, 4, and 

 34 for cocoanut oil. The addition of 10 per cent of cocoanut oil to butter increased 

 the third determination to 10.2 and the addition of 90 per cent to 29.1. In no 

 instance did the alcoholic solution show a higher number than 8.4 for pure butter. 



Plant lecithin; a preliminary communication, E. YVintersteix and O. Hie- 

 staxd (Ztselw. Physiol. Chem., 47 (1906), Xo. 4-6, pp. 496-498).— From their studies 

 of the lecithin of cereals, lupines, and grasses, the authors are of the opinion that the 

 name lecithin should no longer be applied to the organic bodies containing phos- 

 phorus, which occur in plants and are soluble in ether and alcohol, but that they 

 should be termed phosphatides as has been suggested for similar products of animal 

 origin. 



Experiments on amino acids, polypeptids, and proteids, E. Fischer (Ber. 

 Dent. Chem. Gesell, 39 (1906), pp. 530-610).— The cleavage of proteids yields, in addi- 

 tion to ammonia, albumoses, peptones, and finally amino acids. Albumoses and 

 peptones are complex bodies but the acids are comparatively simple and the study 

 of the chemical structure of proteids has been approached through this group. 



The investigations have included synthesis and other studies of such acids, and 

 several new and important methods of working with them and other products of 

 proteid hydrolysis have been evolved. The general purpose of the author's work at 

 present is to unite two or more amino acids to form a complex molecule and in this 

 he has been successful and about 70 such bodies have been produced by his methods. 

 The name polypeptids is proposed for these compounds, which are designated dipep- 

 tids, tripeptids, etc., according to the number of acid radicals entering into their struc- 

 ture. A tabular list of polypeptids is given. As a class polypeptids exhibit many 



