DAIRY FARMING DAIRYING. 



505 



The resistance seems to depend on individual peculiarities of the cows, other than 

 their age or the stage of the period of lactation. It is, however, greatly increased in 

 the milk of strippers during the last month of the lactation period, and is consider- 

 ably below normal in colostrum milk, during the first days after calving. It increases 

 rapidly from this time up to the tenth or twelfth day, after which time it again falls, 

 and varies within the ordinary limits. The resistance of the milk increases with 

 the progress of the act of milking, the strippings having the highest resistance of any 

 portion of the milking. 



So long as the milk does not sour its electrical resistance remains constant, but no 

 direct correlation was found in the case of new milk between the degree of acidity of 

 the milk, as obtained by titration with an alkali solution, using phenolphthalein as 

 an indicator, and the electrical resistance of the milk. No difference in the resistance 

 was observed between milk produced on pasture and that produced on dry feed, nor 

 does there appear to be any breed characteristic in this respect. 



The general average of 660 single determinations of the electrical resistance of 

 cow's milk was 232 ohms, with a probable error of 14.28 per cent. The addition of 

 water increases the electrical resistance of milk, although the results are not decisive 

 when only small quantities of water are added. With the addition of 10 per cent of 

 well water, the probability of adulteration, as shown by the results of the author, is 

 0.522; with 20 per cent, 0.881; with 30 per cent, 0.991, and with 40 per cent, 0.9996. 

 There is no correlation between the resistance of milk and its specific gravity, or its 

 content of total solids, nor does any direct correlation exist with the ash content of 

 the milk, although a certain parallelism is apparent, especially when the ash content 

 of the nonfatty solids is compared with the figures for the resistance of the milk. 



All the milk components conducting electricity are present in the milk serum 

 passing through a porous filter, while milk freed from its mineral components no 

 longer conducts electricity. The electrical conductivity of the milk depends pri- 

 marily on the ash of the milk, especially on the chlorids, and next on the phosphates 

 and sulphates. — f. w. woll. 



Splitting up of fat globules in cows' milk on agitation, C. Barthel (North 

 Mejeri Tidn., 19 (1904), No. 25, pp. 331, 332) .—The author determined, by means of 

 the Babcock method, the number of fat globules in milk before and after heating to 

 55° C, and churning the same for 5 to 90 minutes in a Holstein churn, run at the 

 normal rate. An increase in the number of globules in 1 cu. mm. of milk was 

 observed in every case when the milk had been heated and churned, the increase 

 being larger the longer the milk was churned. While the Gottlieb method gave 

 identical results in the case of all samples of milk, the fat content obtained by the 

 Adams method decreased with increasing length of time churned. The following 

 series of trials illustrates the relations observed: 



Relation between length of churning and number of globules. 



— F. W. WOLL. 



On fat determinations in separator skim milk and buttermilk, E. Holm 

 (Mdlkeritid., 17 (1904), No. 14, pp. 260-262). — A discussion of the relative merits of 



