AGRICULTURAL CHEMLSTRY AGROTECHNY. 309 



For the fat-free dry substance (P), therefore, P=282 (D— 1)+0.19 B. For 

 the percentage of fat in the dry substance (M) the formula is as follows: 



ivi-»* 282+1. I9B 



(D-l). 



Fat content and specific gravity of milk solids, Witte (Ztschr. Untersuch. 

 Nahr. u. Genussmtl., 18 (1909), No. 8, p. -'iS-'t). — The author made the observa- 

 tion that the fat content of the dry substance (p) stands in a definite relation 

 to the specific gravity of the milk-dry substance (m), thereby enabling the 

 direct calculation of the latter. A table is presented giving the specific gravity 

 corresponding to various percentages of fat, there being a decrease of 0.01 per 

 cent in the specific gravity for every increase of 1.1 per cent of fat. These 

 factors only apply to conditions in which the fat content is between 20 and 32 

 per cent, as outside of these limits the calculation must be made by the usual 

 method. 



Hart's casein test, F. T. Siiutt [Canada Expt. Farms Rpts. 1909, pp. 192, 

 19S). — A comparison of this test (E. S. K., 19, p. 707) and the ordinary chem- 

 ical method gave the following results : Out of 7 samples Hart's test yielded 

 in 2 cases 0.1 per cent less than the chemical test, in 2 other cases 0.1 to 0.2 

 per cent less, and in the remaining 3 cases between 0.2 and 0.3 per cent less. 



The nitrogen factor for casein, H. D. Richmond (Analyst, 33 (1908), No. 

 386, pp. 179-184; abs. in Molk. Ztg. [Hildesheim], 23 (1909), No. Jt2, p. 1191).— 

 After calculating the results to fat, ash, and aldehyde-free casein, the factor 

 6.39 was obtained. Comparing the Kjeldahl with the Dumas method, the 

 author concludes that the former furnishes the more accurate results. 



[The relation between the protein and the aldehyde figure of milk], H. D. 

 Richmond (Anali/st. 33 (I'JOS), No. 385, pp. IL'f-UG; abs. in, Molk. Ztg. 

 [Hildesheim], 23 (1909), No. 42, p. 1191).— The author believes that the alde- 

 hyde figure can be employed as a rapid method for the determination of nitrog- 

 enous bodies in milk. According to his investigations the aldehyde figure 

 multiplied by 0.171 gives approximately the protein content of the milk, provid- 

 ing that strontium hydroxid is used in the titration. For woman's milk the 

 factor is 0.13G. The factor 0.171 is not applicable to milk preparations. 



The sin-acid and sal method for the determination of fat in milk, K. 

 WiNDiscH (Milchw. Zentbl., 5 (1909). No. 8. pp. 3'/'/-3.52).— With fresh milk 

 both methods yielded good results, the difference seldom being over 0.1 per cent. 

 The results attained also agreed well with Gerber's sulphuric acid method, 

 except that with milks having a high fat content the alkali method differed 

 markedly in its results. Milks preserved for several weeks by potassium 

 bichromate did not give good results when tested with the sin-acid and sal 

 methods, and indicated that these methods are inapplicable for such milks. 

 The sulphuric acid method, on the contrary, yielded good results. 



[The alcohol test with milk], A. Auzinger (Milchw. Zentbl., 5 (1909), Nos. 

 7. pp. 293-31.'); 8, pp. 352-310; 9, pp. 393-^11) .—The author concludes that the 

 alcohol reaction with fresh milk is not dependent upon the amount of acid pres- 

 ent but is probably caused by a transference of the calcium in its relation to the 

 protein substances. This, however, does not apply to colostrum. It is thought 

 that the positive test occurs much more frequently than indicated by Henkel. 

 The alcohol test combined with the leucocyte test, Koning catalase test, and 

 the Schardinger reaction is considered a good means for the hygienic control 

 of milk. 



On Jaffe's colorimeter method for the estimation of creatinin, A. C. Chap- 

 man (Analyst, 34 (1909), No. 4O-',, pp. 475-483; Chem. News, 100 (1909), No. 

 2602, p. 175). — Several suggestions are made for the satisfactory carrying out 

 of this method. 



