330 
In these cases the variation in the composition of the 
samples tested is not large, although it is as much as usually 
occurs in the milk of a single cow for a like period and 
much more than wouid be expected in the mixed milk of a 
herd. 
It is not to be supposed that the coefficients given above 
are applicable to milk from other sources, nor even to that 
from the same cow for an indefinite period; they must be 
confirmed or corrected by occasional analyses. I believe, 
however, that no material change will be found in these 
coefficients for milk from the same source so long as the re- 
lation between the specific gravity and the viscosity remains 
nearly uniform. Should the specific gravity increase or di- 
minish considerably without a corresponding change in the 
viscosity, a change in the ratio of fat to solids not fat is in- 
dicated. This would of course change the coefficient of 
viscosity for the solids and necessitate an analysis. 
I trust- when more data are obtained that the relation be- 
tween specific gravity and viscosity may be so estabiished 
that corrections in the coefficients of viscosity may be made 
without the trouble of an analysis. 
ANALYSES OF BUTTER. 
In December of last year several samples of butter from 
the Chicago Live Stock Show for 1885 were furnished to the 
Station, by Major Alvord of Houghton Farm. This col- 
lection consisted of both genuine and adulterated butters 
exhibited at the show. They were designated by number 
only, the key being held by Major Alvord till the examina- 
tion was completed. 
The samples were first subjected toan examination for 
adulterations, by several different tests, the chief depend- 
ence being placed upon a‘partial determination of volatile 
fatty acids by Reichert’s method. There were also deter- 
minations made of the insoluble fatty acids, and the melt- 
ing points of both the butter fats and the insoluble fatty 
acids derived from them. 
At the time these butters were received there was consid- 
erable controversy regarding the efficiency of Dr. Taylor’s 
method for the detection of adulterations in butter by means 
of the microscope. An excellent opportunity was offered 
in these samples for testing this method in an impartial 
manner, and a microscopical examination of them was 
made before the nature of the butters was revealed by other 
tests. The butters were examined directly with polarized 
light and a selenite plate. and afterwards the crystals from 
the melted butters were examined in the same way for the 
“St. Andrews cross.” | 
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