384 
Keport of the Chemist of the 
butter fat is about 100; that of lard, tallow, oleomargarine oil and all 
of the commercial substitutes for butter are upwards of 1,000, so that 
this test is amply sufficient for this discrimination. Butters, however, 
vary greatly in composition, and consequently there is a wide range of 
viscosity for the solutions of butter soaps. This range is so great that 
over 30 per cent of adulteration may be added to the butter giving 
the least viscous soai solution before the higher limit for butter .is 
passed. This at first seems sufficient to condemn the method, but an 
examination of the tests for adulteration, which are generally accepted 
by chemists, shows them to be no more reliable than the test proposed, 
while most of them are more complicated and difficult of manipulation. 
I give below extreme figures which I have myself found by Reichert's 
and Koettstorfer's test, and in connection with them the amount of 
lard of average composition which must be added to the butter giving 
the highest figure to reduce it to the lowest: 
Per cent of 
lard neces- 
Maximum. 
Minimum. 
sary to re- 
duce max. 
to min. 
17 
11.3 
33.6 
Koettstorfer 
233 
220 
34.2 
The methods mentioned in this table are the ones most generally 
employed by chemists for the detection of adulterations. I believe, 
therefore, that the viscosity test is fully a<* reliable for this purpose as 
any which has been proposed. 
The real difficulty lies not in any of the proposed tests, but in the 
variable composition of butter, that from different breeds, and even 
from single cows of the same breed, having very different properties. 
It is not probable that the butter from herds and creameries where the 
milk of a large number of cows is received, would give figures by an\ 
of the above tests which differ much from the average. Still the pos- 
sibility always exists that a sample of butter which gives the minimum 
test may or may not be pure, and I believe that no single test is com- 
petent to discriminate absolutely between some pure butters and 
others which contain as much as 30 per cent of adulteration. On this 
ground I would urge upon chemists the necessity of applying as many 
tests as are available in all cases where doubtful figures are obtained. 
The tests which I would recommend for the detection of adulteration 
