398 
Journal of Agricultural Research 
Vol. XIV, No. io 
COMPARISON OR RESULTS BY THE DUCLAUX AND THE DYER METHOD 
A comparison of the Duclaux and the Dyer method was made on a 
solution of volatile acids obtained from silage in the following manner. 
Three hundred gm. of expressed juice from silage were acidified slightly 
with normal sulphuric acid and distilled in a current of steam under 
reduced pressure. Four liters of the distillate were collected. Five 
hundred cc. of this distillate were carefully neutralized with N/io sodium 
hydroxid, and evaporated to a small volume. The volatile acids were 
liberated from their sodium salts by adding the theoretical amount of 
sulphuric acid. The quantitative determination of volatile acids was 
then made by Dyer’s method. 
One thousand cc. of the 4-liter distillate were carefully neutralized 
with barium hydroxid, evaporated to a small volume, and the acids 
freed from the barium salts by the addition of the required quantity of 
normal sulphuric acid. After filtering off the barium sulphate, the 
solution was made up to volume and the acids determined by the 
Duclaux method. 
A comparison of the results by the two methods is given below. 
Volatile acids in 100 gm. of pea-silage juice, as determined by — 
Dyer 
Duclaux 
method. 
method. 
Gtn. 
Gm. 
Acetic acid... 
0. 601 
Propionic acid. 
. °33 
•037 
Total volatile acids. 
.66 2 
.6*8 
Volatile dcids in corn-silage juice, 
as determined by — 
Dyer 
Duclaux 
method. 
method. 
Gm. 
Gm. 
Acetic acid. 
0. 796 
Propionic acid. 
. 082 
Total volatile acids. 
.878 
The above results are typical of several determinations of the quan¬ 
tities of volatile acids in the juices of different kinds of silage by the 
two methods. In all determinations the orientation tests as described 
by Dyer were made for the individual volatile acids, and their presence 
or absence was confirmed. The results indicate a slight difference in 
the proportions of acids found by the two methods; yet this difference 
easily falls within the limits of experimental error, and it is obvious that 
either method is applicable for a comparative study of volatile acids in 
silage. 
