DAIRY FARMING DAIRYING. 579 



Acidity of cow's milk, A. Chretien {Hyg. Tiande et Lait, 7 (1913), A'o. 5, 

 pp. 2^-251, fig. 1). — Normal milk was found to contain from 1.04 to 2 gm. 

 of lactic acid per liter, while colostrum contained slightly less. The feeding 

 of a liquid distillery residue did not materially affect the acidity of milk. The 

 acid content evidently increased with length of lactation period. Milk from 

 a tubercular udder showed a decrease in acidity, while that containing Bacillus 

 mastitidas, B. coli, staphylococci, and streptococci showed a greater acid con- 

 tent than normal milk. 



Observations on the fat globules in milk, W. F. Cooper, W. H. Nuttall, 

 and G. A. Freak {Jour. Agr. Set. [England], 5 (1913), No. 3, pp. 331-356, 

 figs. 6). — The fact that there exists such a wide A^ariation in both quantity and 

 quality in samples of butter from different creams leads to the question 

 whether any function of the fat globules (size, number, etc.) influences this 

 variation. In this paper the authors report their investigations on the variable 

 factors which might affect the " churnability " of cream and continuing previous 

 work (E. S. R., 25, p. 582). 



Analyses were made to determine the nitrogen-containing constituents in the 

 milk serum and to ascertain their influence on the churnability of cream. 

 However, " no correlation could be found between these figures and those 

 obtained with the churnability apparatus and the other determinations which 

 were made; this is probably due to the large number of factors involved." 



Tests were conducted to determine the optimum temperature for churning, 

 fresh creams containing 30 and 25 per cent of fat being churned at 54, 58, and 

 62° F. 



Tables are given showing the weight of butter obtained and the percentage 

 of fat lost in the buttermilk for different breeds of dairy cattle. The results 

 are platted in curves showing the percentage of fat converted into butter at 

 the various temperatures. " The most definite conclusion which can be drawn 

 from these experiments is that the percentage of fat in the cream has a very 

 marked influence upon the percentage conversion of fat into butter." 



The mean size of the fat globules contained in the milks from which the 

 creams were obtained is given, but no correlation could be determined between 

 the percentage conversion and size of globules. With regard to the limiting 

 surface of the globules, the authors hold to the view that " constituents of 

 the milk serum are adsorbed to the surface of the globule." 



Feeding experiments were conducted to determine the effect upon the fat 

 globules of high, low, and medium proteid feeds. The variations were very 

 irregular, and the " only conclusion which can be drawn from these experi- 

 ments is that the food has little or no influence on the size of the globules, 

 if the ' ratio ' is taken as the criterion." 



It is noted that the mean sizes of the globules of the Jersey and Guernsey 

 breeds were not found larger than the average, while those in the milk from 

 grade Shorthorns are considerably larger than those of the Jersey or of other 

 breeds. This is contrary to the general opinion, although other investigators 

 report similar findings. 



The enumeration and ra.easurement of fat globules i:i milk, W. F. Coopek, 

 W. H. Nuttall, and G. A. Freak (Jour. Agr. Sci. [England], 5 (1913), No. 3, 

 pp. 357-376, figs. 2). — In this treatise the authors give complete descriptions 

 of 2 methods of determining the number and size of fat globules in milk. 



The original Babcock method consists in filling glass capillaries with diluted 

 milk and with the aid of an ocular micrometer determining the number of 

 globules in a known volume. The flat cell method consists in making a photo- 

 micrograph of the milk contained in a Thomas-Zeiss Cell, the enumeration and 

 measurement being carried out on a print. From the photograph the number 



