BY H. S. HALCRO WARDLAW. 619 



It was thought that this variable efi'ect upon the conductivity 

 might be due in some way to the method of removal of the fat 

 from the milk. The milk might be concentrated slightly by 

 evaporation during the process of spinning in the centrifuge. 

 The conductivity of the spun milk would then be greater than 

 could be accounted for by the removal of the fat. Or, substances 

 other than fat might be removed by spinning. In this way also 

 the electrolytes of the spun milk might become more concen- 

 trated, and the effect of the removal of the fat would be ex- 

 aggerated. 



To test the first of the above suppositions, the conductivity 

 of samples of milk which had been spun covered to prevent 

 evaporation was compared with the conductivity of samples 

 spun uncovered in the ordinary way. The results obtained are 

 lifiven below. 



Electrical conductivity of milk after spinning in covered and 

 uncovered tubes. 



These results show that there is no appreciable increase of 

 conductivity due to the concentration of the milk by evaporation 

 during spinning. 



To test the second hypothesis, the amounts of total solid 

 matter as well as of fat in the milk were determined. The 

 following Table gives the weights of fat and of total solids in 

 100 c.c. of milk before spinning, and in the volume obtained 

 after spinning (100 c.c less volume of fat). 



