1910.] PUBLIC DOCUMENT— No. 31. 143 



jiiiiyl alcohol, — colored a bright red hy fiiehsin or any common 

 red dye, — a small quantity of which is dropped on top of the 

 fat column at the completion of the test. Being lighter than 

 butter fat it floats upon the fat, doing away with the meniscus 

 and giving a sharply defined line between alcohol and fat. Far- 

 rington,^ at the suggestion of Babcock, recommends ethyl alcohol 

 saturated with butter fat, which is used in the same manner as 

 the amy] alcohol. '' The fat-saturated alcohol is prepared by 

 adding about a teaspoonful of butter fat to 6 ounces of alcohol 

 in a bottle. Warm and shake the bottle until the alcohol has 

 dissolved all the fat possible ; some of it will be left undissolved 

 at the bottom of the bottle." Butter fat at the temperature 

 when usually read has a specific gravity of 0.9. It is necessary 

 to have the alcohol reasonably pure, otherwise there is a pos- 

 sibility of its being heavier than the butter fat, in which case it 

 would pass through the fat column instead of floating on top. 

 Ethyl alcohol containing 42 per cent, water has approximately 

 the same sjiecific gravity as butter fat. 



OBSERVATIo^^s AT THIS Station, 

 Six-inch test bottles having as wide a diversity in size of neck 

 as could be brought together were used. These bottles were 

 carefully cleaned, and before using were washed out with ether 

 to remove all traces of fat. Pure butter fat was then weighed 

 into the bottles on a delicate balance, and enough hot water 

 added to make up to 18 grams. The bottles were then placed in 

 a Babcock tester and whirled three times, five, three and two 

 minutes, respectively, as for the regular test. Readings includ- 

 ing and without the upper meniscus were taken immediately; 

 alcohol according to the Farrington method was then added and 

 readings again taken. The theoretical readings were then 

 computed and the results compared. Following is the tabulated 

 data : — 



* Special circular, Wisconsin Dairy School. 



