DAIRY FARMING DAIRYING. 179 



was treated in a similar way as above stated, and washed with sugar 

 solution until the washings were not colored. The washed cream thus 

 obtained was more highly colored than the first portion, being of a 

 dark-red color. Microscopic examinations showed that the fat globules, 

 while themselves colorless, were surrounded by a narrow, faintly red- 

 colored border. 



With nigrosin the washed cream of the first portion assumed a light 

 bluish gray color, and that from the second portion a darker color. 

 The globules in the latter appeared under the microscope surrounded 

 by a narrow bluish violet border. 



An experiment was made on the churning qualities of washed cream. 

 It was found that it churned in a manner similar to ordinary cream; 

 the butter came after 30 minutes, and the buttermilk separated as 

 usual. The quality of the butter was poor, its flavor being very 

 tallowy. Chemical analysis of the butter showed the following com- 

 position : Water 14.07 per cent, fat 84.81', nitrogeneous substance 0.35. 

 (nitrogen* 0.049 per cent), ash 0.02, nitrogen per 100 parts of fat, 0.058 

 parts, and albuminoids 0.412 parts. 



The author believes that the membrane is more condensed or viscous 

 nearest to the globules, becoming more watery toward the circumference, 

 and that in separating milk by centrifugal power, as by other violent 

 treatment, a part of this outer covering is loosened from the globules. 

 He finds by calculations based on specific-gravity determinations that 

 the average thickness of the membrane is 0.104 of the radius of the fat 

 globules, and that the fat globules are composed of 72.5 per cent pure 

 fat and 27.5 per cent albuminous membrane. 



The term "serum difference,'' viz, the difference between the com- 

 position of the butter serum and the serum of the buttermilk from the 

 same churnings, corresponds to what the author 1 in 1883 called "casein 

 hydrate," which he then believed was formed during the churning proc- 

 ess but now shows to be present in the milk and carried over into the 

 cream and the butter with the fat globules. This "serum difference," 

 in the authors opinion, is identical with the slimy membrane of the 

 fat globules. While the "serum difference" of sour-cream butter 

 includes more albuminoid matter than that of sweet-cream butter, the 

 composition of the "serum difference" of either kind is quite constant. 

 The following statement shows the average data obtained from 24 

 experiments: 



Composition of "serum difference." 



Sweet-cream Sour-cream 

 butter. butter. 



Percent. Percent. 



Albuminoid matter (i. 42 7. 49 



Asb l . OS 1 . 09 



Water 92 55 91.42 



Total i 100.00 100.00 



1 Investigations on the formation of butter by churning, and of tbe physical and 

 chemical composition of butter. Rpt. Expt. Sta., Copenhagen, 1883. 



