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38387 
The properties of butyric acid are essentially different 
from those of the other acids of butter or its substitutes, in 
that it is volatile, soluble in water, and has, comparatively, 
a low molecular weight. 
Upon these characteristic properties of butyric acid are 
based nearly all of the tests for adulteration which are con- 
sidered reliable, and as it occurs in all genuine butters, its 
absence is conclusive evidence that the sample examined is 
spurious. The quantity found is, within certain limits, a 
measure of the amount of adulteration. 
Reichert’s method, which is the one at present most gen- 
erally adopted, depends upon the amount of volatile fatty 
acids obtained, under certain prescribed conditions, from 
2.5 gms. of fat. ‘There is required for neutralizing the fatty 
acids obtained by this process from genuine butter about 
14 c.c. of #5 normal soda solution. The range is from 12.5 
c.c. to over 16 c.c. for pure butters. The fats used for butter 
adulteration require from 0.5 to 5. c.c. 
Hehner and Angell proposed the estimation of insoluble 
fatty acids as a measure of adulteration. The average 
amount of insoluble acids as found by the authors in genuine 
butter was 87.24 per cent, and varied in the samples exam- 
ined from 86.1 to 88.2 per cent. Twenty-one samples ex- 
amined in the laboratory of the New York Dairy Commis- 
sioner gave an average of 88.33 per cent, with a range from 
86.40 to 90.24 per cent. 
Thirty-one samples examined by Dr. Wiley, at Washing- 
ton, averaged 88.17 per cent. with a range from 86.43 to 
89.89. ‘These determinations give an average for American 
butters of about 88.2 per cent. with a range from 86.4 to 
90.2 per cent. 
The amount of insoluble acids in lard and beef fat is over 
95 per cent. and about the same for cotton-seed oil. 
The soluble acids in butter amount to about 5 per cent. 
with a range of one per cent. either way. Lard and oleo- 
margarine oil contain none at all. 
On account of the low molecular weight of butyric acid 
more alkali is required to saponify butter fats than any of 
the fats with which it is adulterated. Koettstoerfer has. 
shown that one gram of butter fat requires 221 to 233 mili- 
grams of potassium hydrate, and one gram of other animal 
fats 195 to 197 miligrams. The range for American butters 
is about the same. The average derived from analyses of 
Wiley and Martin is 225 miligrams. 
For convenience of comparison the range for each of the 
above methods is presented in tabular form. The last 
column shows the amount of adulteration, lard, oleo oil, 
etc., which may be added to an average sample of butter 
