New York Agricultural Experiment Station. 377 
I shall consider the relation which the figures given by these tests 
"bear to the chemical composition of the butter fats; the difference in 
the composition indicated which may be attributed to breed and to 
individuality of cow, and finally the bearing which these variations 
have upon butter standards and the detection of adulterations. 
I. Volatile Fatty Acids — Reichert's Test. 
The principal distinction between butter and other fats is found in 
the presence in butter of a considerable amount of glycerides of vola- 
tile fatty acids. The acids of this class which have been identified are 
butyric, capric, caproic, and caprylic; of these the first largely pre- 
dominates and it is customary to consider all of the volatile acids as 
butyric. Reichert's test depends upon the amount of these volatile 
fatty acids which are obtained in a specified manner from 2.5 gms. of 
fat. It is expressed by the numbers of cubic centimeters of decinor- 
mal alkali required to neutralize this acid. The alkali required is not 
an equivalent for the total volatile acid of the butter, although it 
appears to have quite a uniform ratio to them. Waller's results show 
that the figures obtained by Reichert's test represented about 80 per 
cent of the total volatile acids expressed as butyric. (N. Y. Dairy Com- 
missioner's report, 1886, p. 240.) 
While these butters differ widely in the amount of volatile acids, 
there seem to be no differences which can be attributed to breed; the 
average and extreme figures for the Jerseys, Holsteins and others 
being nearly the same. The extreme variation is from 11.5 c. c. to 16.1 
c. c, the average for all determinations being 13.95 c. c. Reichert gave 
the mean value as 14 c. c, the lowest limit for pure butter being placed 
at 12.5 c. c. All of these samples except Nos. 5 and 15 fall within 
these limits. These butters, so exceptionally low in volatile fatty acids, 
were tested several times and always with practically the same results. 
These low results cannot be attributed to breed and are probably not 
due to food, as the dairy butter No. 2, which is above the average, is 
from the herd to which the single cow No. 5 belonged. The only 
other case in which figures so low as these have been obtained, from 
butter known to be pure, is mentioned by Cornwall and Wallace (Zeit. 
Ann. Chem., Heft 3, 1887), who found in a sample of butter made from 
milk of a grade Alderney 11.3 c. c.-ll. 5 c. c. These tests extended 
over a period of several weeks and were repeated many times by each 
of the investigators. This exceptionally low figure could neither have 
been due to breed nor to food, as this cow belonged to a herd of eight 
of the same breed, all receiving the same care, the remaining cows of 
the herd ranging from 12.2 c. c. to 15.1 c. c. 
48 
