6Y4 EXPERIMENT STATION RECORD. 



The comparative composition of human milk and of cow"s m.iik, E. B. 

 Meigs and 11. L. Marsh {Jour. Biol. Chem., IG (.1913), No. 1, pp. 147-168, 

 figs. 2). — "Human milk differs from cow's milk in three important ways. It 

 contains considerably more lactose than cow's milk and more substances of un- 

 known nature which contain little or no nitrogen; it contains very much less 

 protein than cow's milk. The composition of milk varies more or less regularly 

 with the progress of lactation so that average figures for its composition are 

 not very satisfactory. The following, however, may be taken as the limits 

 of normal variation of the constituents of the two kinds of milk from the be- 

 guming of the second month of lactation onward, the figures representing per- 

 centages of whole milk. Human milk, protein 0.7 to 1.5 per cent, fat 2 to 4 

 per cent, and lactose 6 to 7.5 per cent; cow's milk, protein 2.5 to 4 per cent, 

 fat 2 to 4 per cent, and lactose 3.5 to 5 per cent. 



"Both kinds of milk contain substances [some of which can be crystallized], 

 which are important constituents of diet, which are soluble in alcohol and 

 ether, which contain little or no nitrogen, but of which the chemical nature 

 is still unknown. These substances are most plentiful in early human milk 

 find diminish in amount with the progress of lactation. Early human milk 

 contains about 1 per cent of these unknown substances; milk from the middle 

 period of lactation about 0.5 per cent. Cow's milk from the middle period of 

 lactation contains about 0.3 per cent of the unknown substances." 



Many of Camerer and Soldner's results were verified. 



On the hygienic bacteriological character of Bern market milk with ref- 

 erence to the presence of tubercle bacilli, J. Thoni (Centbl. Bakt. [etc.], 1. 

 Alt., Oriij., 77/ (i9i4), Nos. 1-2, pp. 11-69, fig. 1). — Tests were made and the 

 results compared of the leucocyte, fermentation, catalase, and alizarol methods 

 and the germ estimate or count. Aside from the catalase test all demonstrated 

 the need of a strict hygienic control of market milk. The leucocyte and fermen- 

 tation tests were considered the most practical for genex'al use. 



A new method of determining milk quality, F. H. Hall {'Sew York State 

 Sta. Buls. 313 and 380, popular ed. {1914), PP- 3-15, pis. 2). — This is a popular 

 edition of Bulletins 372 and 3S0, previously noted (E. S. R., 31, pp. 78, 372). 



Cream testing, H. II. Dean (Ami. Rpt. Ontario Agr. Col. and Expt. Farm, 

 S9 (1913). pp. 95-99). — Continuing previous work (E. S. R., 30, p. 74), a com- 

 parison of weekly, semimonthly, and monthly composite tests showed all of 

 these methods to be practically correct. Composite samples kept in open bot- 

 tles tested too high. There was not much difference in the average results, 

 whether glass, cork, wood, or paper cap stoppers were used. Creosote proved 

 to be a good preservative and has the advantage of requiring less sulphuric 

 acid for a test than the preservatives commonly used. Formalin as a pre- 

 servative tends to require a larger volume of sulphuric acid when making the 

 test. 



A new casein-fat milk test is described, in which 20 cc. of acid mercuric 

 nitrate (made by dissolving mercury in twice its weight of nitric acid, of a 

 specific gravity of 1.42, to which an equal bulk of water is added after solution 

 and diluted with 30 times its bulk of water) is placed in a test bottle, then 5 cc. 

 of milk, and the whole allowed to stand from six to seven minutes without 

 shaking. The temperature of the milk and acid should be between 65 and 70° F. 

 The bottles are then placed in a centrifuge, 15 in. in diameter, and whirled at 

 a speed of 2.000 revolutions jier minute for from seven to eight minutes. The 

 bottles are then read in percentage as combined casein and fat. 



Results of this test agree quite closely with separate determinations of fat 

 and casein made by other methods. 



