ANALYTIC PROCESSES 15 
paper. From a weighing bottle about 5 grams 
of the milk are transferred to the coil by means 
of a pipet, care being taken to keep dry the end 
of the coil held in the fingers. The coil is 
placed, dry end down, on a piece of glass and dried 
for one hour, preferably in an atmosphere of 
hydrogen; it is then transferred to an extraction 
apparatus and extracted with absolute ether, 
petroleum spirit of boiling-point about 45° or, 
better, carbon tetrachlorid. The extracted fat 
is dried and weighed. 
The above procedure is very satisfactory, but 
the drying in hydrogen may usually be omitted. 
After the coil has received at least twenty wash- 
ings, the flask is detached, the ether removed by 
distillation, and the fat dried by heating in an 
air-oven at about 105°, and occasionally blowing 
air through the flask. After cooling, the flask 
is wiped with a piece of silk, allowed to stand 
ten minutes, and weighed. 
Richmond states that. to perform a rigidly 
accurate determination attention to the following 
points isnecessary: The ether must be anhydrous 
(drying over calcium chlorid and distilling is 
sufficient). Schleicher & Schuell’s fat-free papers 
should be used, and one should be extracted 
without any milk on it, as a tare for the others. 
Four or five hours’ extraction is necessary, and 
