New York Agricultural Experiment Station. 
385 
ure first, on account of the economy of time and ease of manipulation, 
the viscosity test as described above, and second, Reichert's test 
The combination of these two tests, depending as they do upon 
entirely different properties of the fats, will in nearly all cases be 
sufficient. Should the viscosity exceed 500 there is no doubt of its 
adulteration, and no further test need be made. Butters giving 
viscosities between 200 and 500 are doubtful and should be submitted 
to further examination. 
It is probable that the viscosity of soap solutions from butter 
diminish with age. Seven samples of butter tested in May, shortly 
after churning, were tested again in October with the results given 
below. These butters were filtered at the time of first test and kept 
in corked bottles until tested again; they were at this time slightly 
bleached, but were otherwise unchanged in appearance. 
Viscosity in May 65, 69, 62, 61, 69, 68, 65; average 65.6 
Viscosity in October 54, 62, 62, 58, 53, 62, 54; average 57.9 
In the last report I have recommended the determination of 
viscosity as a rapid and efficient means for detecting changes in the 
composition of milk which may occur from day to day, and have 
suggested that it might, to some extent, replace analyses of milk during 
feeding experiments. The data obtained at that time seemed to 
warrant this conclusion. Later tests, however, in the same series, 
showed that changes in the milk may be of such a nature as to cause no 
change in its viscosity. This is shown in the following determinations 
where milks having the same viscosity differ considerably in com- 
position: 
Viscosity 288 Fat 5 . 74 
Viscosity . 288 Fat 5.62 
Viscosity 288 Fat f . . . 4 . 71 
Viscosity 273 Fat 5 . 55 
Viscosity 273 Fat 4.89 
Viscosity 266 Fat 4 . 85 
Viscosity 266 Fat 4.42 
It is evident, therefore, that the test does not accomplish all that I 
hoped it would one year ago. Still it has a value, especially when 
accompanied by analyses, as it will indicate changes in the physical 
constitution of milk which are often of more importance to the dairyman 
than are changes in the amount of solids or of fat. Changes in the 
size of the fat globules or in the viscosity of the milk serum are of this 
49 
