AGRICULTUE AL CHEMISTE Y AGE OTECHN Y. 



13 



weighed as usual. The weight multiplied by 20, plus 2.5, gives the percentage 

 of pure caffein in the sample. 



Chemistry and physiolog'y of milk, W. Grimmer (Chemie und Physiologie 

 der Milch. Berlin, 1910, pp. XII+36J,, figs. 37).— This excellent work contains 

 the following chapters: Structure and function of the mammary glands; the 

 composition and general characteristics of the milk of various animals; the 

 physical characteristics of milk; the proteins of milk; the fat of milk; the 

 carbohydrates of milk ; the salts of milk ; other milk constituents— phospliatid, 

 cholesterin, etc. ; the enzyms of milk ; the bacteria of milk and their antagonists; 

 the immune bodies, lactoserum ; the passage of foreign bodies over into the milk ; 

 sterilization, pasteurization, infants' milk; milk preparations; milk as a nu- 

 trient; and the examination of milk, which includes the physical, chemical, 

 and biological methods. 



The physical chemistry of the calcium chlorid serum of milk, G. Wiegneb 



(Ztschr. Untersuch. Nahr. u. Genussmtl., 20 {1910), No. 2, pp. 70-86). In a 



former communication (E. S. R., 22, p. 514) it was shown that a definite relation 

 exists between the refraction and the specific gravity of the calcium chlorid 

 milk serum, and that within certain wide but definite limits this relation is 

 entirely independent of the composition of the calcium chlorid serum. 



The present article deals chiefly with showing the accuracy of the above con- 

 clusions, with particular reference to the results calculated according to the 

 author's formula and the values actually observed. The results indicate that 

 the specific refraction of the calcium chlorid milk serum is an " additive prop- 

 erty," which can be considered the sum total of the specific refractions of the 

 individual constituents, and that this specific refraction is within certain wide 

 limits independent of the individual constituents. 



The specific volume of the calcium chlorid milk serum is also an " additive 

 property " and can be considered as the sum of the specific volume of the con- 

 stituents of the calcium chlorid milk serum. In this calculation, however, the 

 contraction taking place on solution of the constituents must be considered. As 

 the specific volume has the reciprocal value of the specific gravity, it is thereby 

 possible to estimate the specific gravity of the calcium chlorid milk serum from 

 its composition, in every instance. With the aid of the specific gravity of the 

 dry substance of the calcium chlorid milk serum, which in all probability is 

 constant (1.GS5 at 20° C. when prepared with water at 4°), the dry substance 

 in the calcium chlorid milk serum can be determined. 



Preformed sulphuric acid in milk, J. Tillmans and W. Stjthoff (Ztschr. 

 Untersuch. Nahr. u. Genussmtl, 20 (1910), No. 2, pp. 49-63).— The results show 

 that preformed sulphuric acid is present in woman's, cow's, goat's, and mare's 

 milk in the form of ordinary sulphate-sulphuric acid. The sulphur of milk is on 

 the average distributed in parts per 100 of sulphur as follows : 



Distribution of the sulphur in the milk of various animals. 



Source of milk. 



Cow. 

 Goat, 

 Mare 



Protein 

 sulphur. 



Per cent. 

 84.7 



Organic 

 nonpro- 

 tein sul- 

 phur. 



Per cent. 

 4.9 

 6.3 

 5.8 



Sulphur in 

 the form of 

 preformed 

 sulphuric 

 acid. 



Per cent. 

 10.4 

 5.8 

 4.0 



