ANALYTIC PROCESSES 19 
a small amount of amyl alcohol with an equal 
volume of hydrochloric acid was added to the 
milk, and the proteins thus coagulated dissolved 
by strong sulfuric acid. About the same time 
Babcock devised a process in which sulfuric acid 
was used alone. Subsequently Gerber published 
a process in which the essential feature of the 
Lefimann-Beam method, namely, the use of amyl 
alcohol, was advised. 
The test-bottles have a capacity of about 30 c.c. 
and are provided with a graduated neck, each 
division of which represents 0.1% by weight 
of butter fat. 
15 cc. of the milk are measured into the 
bottle, 3 c.c. of a mixture of equal parts of amyl 
alcohol and strong hydrochloric acid added, 
mixed, the bottle filled nearly to the neck with 
concentrated sulfuric acid, and the liquids mixed 
by holding the bottle by the neck and giving it a 
gyratory motion. The neck is now filled to 
about the zero point with a mixture of sulfuric 
acid and water prepared at the time. It is then 
placed in the centrifugal machine, which is so 
arranged that when at rest the bottles are in a 
vertical position. If only one test is to be made, 
the equilibrium of the machine is maintained by 
means of a test-bottle, or bottles, filled with a 
mixture of equal parts of sulfuric acid and water. 
After rotation for from one to two minutes, the 
