506 EXPERIMENT STATION EECOED. 



The behavior of milk towards ammonium sulphate and a new method 

 for determining lactose, E. Salkowski {Hoppe-Seyler's Ztschr. Physiol. Chem., 

 78 (1912), No. 2, pp. 89-95). — This article deals with the use of ammonium 

 sulphate as a reagent for precipitating the proteins from milk for the purpose 

 of determining lactose in the filtrate. The method is as follows : Fifty cc. of 

 milk is placed in a wide-mouthed, graduated, stoppered glass cylinder of from 

 150 to 200 cc. capacity and treated with 17.5 gm. of ammonium sulphate, then 

 shalven thoroughly, filled up to the 100 cc. mark with a saturated solution of 

 ammonium sulphate in water, mixed, and filtered through a 16-cm. filter. In 

 a few minutes enough filtrate is obtained for the polariscopic determination of 

 lactose. 



In regard to the fat of woman's milk, W. Aenold (Ztschr. Vntersiich. Nahr. 

 u. Gemissmtl., 23 (1912), No. 9, pp. 433-4JiO). — The chemical composition of the 

 fat in woman's milk differs from that contained in cow's milk, not only in the 

 amount of water-soluble substances present but also in the comix)sition of these 

 acids. Cow's milk fat contains a larger a'mount of butyric and less caproic 

 acids, and a little capiylic acid, corresponding to a middle molecular weight 

 of from 100 to 106, while the water-soluble fatty acids of human milk fat con- 

 tain a larger amount of caprylic and caproic acid, and possibly of butyric acid, 

 closely correspond to the acids of coconut fat, and have a molecular weight 

 of 128.9. Furthermore, the oleic acid content of human milk fat is higher than 

 that of cow's milk fat. A close agreement, howevei", is found among the non- 

 volatile fatty acids (insoluble in water). Figures for the molecular weight 

 varying from 259 to 2G2 were obtained. On the other hand, the iodin numbers 

 of the nonvolatile fatty acids of human milk fat are higher than those of cow's 

 milk fat. A mixture of 14 parts of coconut fat and 86 parts of hog fat (lard) 

 gave analytical data which corresponded closely to those with the fat contained 

 in human milk. 



The composition and examination of cow's and goat's milk with par- 

 ticular reference to the refraction of calcium-chlorid serum, K. Alpers 

 (Ztschr. Untersuch. Nahr. u. GcnussmtJ., 23 (1912), No. 10, pp. Jf 97-5 13). —The 

 refraction of the calcium-chlorid serum of individual milks varied between 35.S 

 and 41.3° at a temperature of 17.5° C. In one case, however, where the milk 

 came from an inflamed udder it was 34°, and the milk from cows in heat in 

 some cases showed marlced variations in composition. The daily variation of the 

 refraction, however, never exceetled 1.4°. As an average refraction, from 126 

 samples of milk taken in the barn the figure 39.11° was obtained. This method, 

 according to the author, is a very valuable one for detecting added water to 

 milk, but care must be taken in all cases not to overrate its value. 



With goat's milk the refractions were from 34.7 to 40.3, with an average of 

 38°. The average specific gi-avity of goat's milk was 1.03, the average fat con- 

 tent 4.3, and the fat-free dry substance 8.89 per cent. 



The most important enzym reactions for differentiating boiled from raw 

 milk, especially Schardiuger's reaction, A. Groger (Die wichtigsfcn Enzyin- 

 reaktioncn zur Untcrscheidung roher und gckochter Milch. Inaug. Diss., Univ. 

 Leipsic, 1911, pp. 6t). — Although Rothenfusser's reaction with paraphenyleno- 

 diamin hydroohlorid in the hands of skilled persons is a good method for differ- 

 entiating boiled from raw milk, it can not be recommended for use by the laity. 

 The preparation of a serum, howevei', in this method is not necessary, as the 

 boiled milk after standing for a time with this reagent will show a ix>sitive 

 coloration. Taking everything into consideration the author believes that the 

 Webber-Arnold guaiac reaction should be given the preference. Schardiuger's 

 reaction, on account of its requiring a water bath, is only of use in the labora- 

 tory, and since the reaction is influenced by the presence of much acid (as in 



