382 
Report or the Chemist of the 
For the detection of adulterations in butter, and probably in other 
fats, the determination of viscosity of the soap solutions is a rapid 
method, easy of manipulation, and as efficient as any of the chemical 
methods in general use. The ran^e in the butters from single cows 
appears much greater than that shown by other methods. This differ- 
ence, however, means no more in per cent of adulteration than do the 
smaller differences shown by Reichert's or Koettstorfer's method; for 
all of the commercial adulterations, such as oleomargarine or butter- 
ine, which rarely contain less than fifty per cent of adulteration, the 
results are never doubtful. In any known sample of butter the addition 
of one per cent of lard, oleomargarine or cottonseed oil is easily 
detected. The readiness with which slight changes in the composition 
of butter may be shown renders this examination of value in feeding 
experiments, for determining the effect of foods upon the butter fats. 
Conclusions. 
The variations in the composition of butter, as shown by these 
examinations, are much greater than has been generally supposed, and 
occur not only in the amount of volatile fatty acids, but affect all of 
the constituents of the butter. 
These variations are especially marked in those butters made from 
the milk of single cows, where the extreme values are so widely sepa- 
rated as to render doubtful the detection of even thirty per cent of 
adulteration by means of any single test. It is, however, unlikely 
that a pure butter will be found deficient in all respects, so that in 
doubtful cases the application of as many tests as possible is 
advisable. 
The influence of breed of cow upon the composition of the butter 
fat is no less marked than it is upon the composition of the milk, and, 
contrary to general acceptation, does not appear to be materially 
affected by the character of the food. 
The amount of stearine in butter has been largely over-estimated; 
instead of thirty to forty per cent it is probably less than three per 
cent in most butters. It is only on this supposition that the high 
saturation equivalent of butter fat, and the low viscosity of solutions 
of its soaps, can be explained. 
The Use of the Viscometer. 
The experience of another year with the viscometer has confirmed 
my impressions, given in the last annual report, concerning its value 
as an aid in the study of butter and other fats. For the detection of 
adulterations in fats and oils, the method proposed is as reliable as 
any of the chemical methods in general use, and has the advantage 
