60 REPORT OF DEPARTMENT OF BACTERIOLOGY OF “THE 
appear until after standing some hours. With larger amounts 
of chloroform it forms promptly and, while it mixes with the 
milk on shaking, it promptly settles out. Measurements of the 
depth of the layer formed after*the addition of 40 per ct. of 
chloroform showed it to be as deep at the end of 4 hours as after 
10 days. Where it is present in considerable quantities, the 
volume of this opaque material is approximately equal to the 
volume of the chloroform which has been added. Where chloro- 
form is added in large quantities, the milk standing above this 
opaque layer becomes noticeably more translucent, indicating 
that a portion of the casein has been carried down. 
Mr. Bosworth siphoned the milk from above such a layer in a 
bottle of milk which had contained 10 per ct. of chloroform. 
The chloroform layer with a little of the milk was transferred to 
a separatory-funnel and allowed to stand over night. In the 
morning one-half of the chloroform layer was drawn off into an- 
other separatory-funnel and to this was added some water and — 
the mixture well shaken for a half hour or more. It was then 
allowed to settle and after a distinct separation of the two liquids 
all of the chloroform and one-half of the water were drawn off. 
The remaining half of the water was transferred to a beaker. 
The solution was of a milky appearance and upon the addition 
of a slight amount of 1 per ct. acetic acid a precipitate settled 
out, which upon examination proved to be casein. 
From these observations it would seem clear that the chloro- 
form, in excess of what passes into solution if the serum of the 
milk, settles to the bottom and carries down with it a portion 
of the casein. The casein is apparently not altered by entering 
into this relation with the chloroform since, upon being shaken 
with an excess of water, it passes in suspension into the water 
from which it can be precipitated by acid in the same form in 
which it is normally thrown down from the milk. 
CONCLUSIONS. 
Solubility.— The solubility of chloroform in skim-milk 1s ap- 
proximately 0.55 per ct. by volume. In normal milk the solu- 
bility of chloroform depends largely upon the percentage of fat 
present. Five per ct. of fat dissolves approximately 1.0 per ct. 
of chloroform. The affinity of chloroform for fat is marked and 
the resulting saturated solution is heavier than the milk, collecting 
at the bottom of the container. 
