38 Report OF DEPARTMENT OF BACTERICLOGY OF THE 
When the chloroform present is sufficient to saturate the milk 
and the fat, the excess associates with some of the casein and 
goes to the bottom, forming there the white layer referred to above. 
While the formation of this layer can be observed within a few 
minutes in the presence of a marked excess of chloroform, the 
material of which it is composed does not all separate quickly 
from the milk and may enter as a disturbing factor in deter- 
minations of the solubility of chloroform in milk, as the follow- 
ing experience will show. At the time that the samples of milk 
containing 5 per ct. of fat were drawn for analysis one of the 
bottles containing I.o per ct. of chloroform was accidentally 
overturned, somewhat mixing its contents. This bottle was al- 
lowed to stand 20 hours, after which samples were drawn and 
analyzed. These samples showed the presence in the body of the 
milk of 0.79 per ct. of chloroform. After standing quietly for a 
week an examination of this same bottle showed that its real 
percentage of chlorcform in solution was like that of its duplicate, - 
0.28 per ct. 
That this variation in the two determinations was really due to 
this material in suspension is made fairly certain by the results 
obtained from an examination of 4 bottles of skim-milk which 
had been shaken 24 hours before examination. Duplicate bottles 
had received 5 and Io per ct. of chloroform 10 days before 
the examination and should have shown 0.55 per ct. of chloro- 
form in solution. The results of the examination made 24 hours 
after shaking varied from 0.90 to 0.94 per ct.. with an average 
of 0.924 per ct. 
SOLUBILITY OF MILK-FAT. 
The solvent power of chloroform upon fat is well known, but 
in the case of milk this expresses itself in such a way as to have 
a distinct influence upon the germicidal value of the chloroform. 
This is well illustrated by the results of an experiment in which 
ten well-stoppered bottles, each holding 150cc. of milk containing 
approximately 5 per ct. of fat, received successive additions of 
o.5cc. of chloroform. There was no visible effect from the addi- 
tion of 0.6 per ct. of chloroform, the fat rising to the top in a 
sharply defined layer; but, when the amount reached 1.0 per ct., 
and more particularly 1.3 per ct., there was sufficient fat diffused 
through the milk to give it a yellow tinge, and the thickness of 
the cream layer was noticeably reduced. With 1.7 per ‘ct. of 
chloroform the cream layer at the top of the milk disappears and 
the fat collects at the bottom of the bottles. In bottles of similar 
