364 
Journal of Agricultural Research 
Vol. VIII, No. 10 
from the silage in a Buchner press, under a pressure of 300 to 400 kgm. 
per square centimeter. This method of sampling facilitates the chemical 
examination, insures a well-mixed sample, and makes possible more 
comparable results. 
The methods used are as follows.: 
Total acidity. —Ten c. c. of silage juice were diluted to about 500 
c. c. with carbon dioxid free water, and titrated with decinormal bari¬ 
um hydroxid solution in the presence of phenolphthalein till a distinct 
pink appeared by reflected light against a white background. 
Volatile acidity. —One hundred c. c. of juice were distilled in a 
current of carbon dioxid free steam. To hasten the liberation of 
volatile acids and alcohols, 100 gm. of sodium chlorid were added to the 
juice. About 600 c. c. of distillate were titrated with baryta water in 
the presence of phenolphthalein. 
Alcohols (Distillation method).—The distillate from the volatile acid 
determination was neutralized with baryta water (solid phenolphthalein 
being added) and concentrated by repeated distillation with sodium 
chlorid (2). About 50 c. c. of alcohol solution were oxidized 1 in a pres¬ 
sure flask in a boiling water bath for 30 to 40 minutes, and the volatile 
acids then distilled off four or five times, with additions of carbon dioxid 
free water. The volatile acids were titrated and calculated as ethyl 
alcohol. 
Alcohols (Aeration method).—In this method (21) a current of air 
was drawn through the silage juice, which was saturated with ammonium 
sulphate, into concentrated sulphuric acid. The sulphuric acid-alcohol 
solution was then oxidized with the potassium dichromate solution, and 
distilled and calculated as in the previous method. Although other 
alcohols are formed in silage in small amounts, all were calculated as 
ethyl alcohol. 
Total sugars. —Fifty c. c. of juice were clarified with neutral lead 
acetate, the excess lead precipitated with anhydrous sodium carbonate, 
an aliquot allowed to stand 24 hours with hydrochloric acid, neutralized, 
and the total reducing sugars determined on an aliquot by either the 
Defren-O’Sullivan method or the slightly modified volumetric method 
of Schoorl (19). In any given series the same method was used to 
insure comparable results. 
Amino nitrogen. —The amino nitrogen was determined on the diluted 
juice with the Van Slyke apparatus (22). This determination shows the 
relative degree of hydrolysis of protein if used on the same or similar 
material at successive periods. 
Ammonia nitrogen.—A 50-c.c. sample of the juice was distilled with 
magnesium oxid, according to the official fertilizer method. 
Moisture. —Samples of about 100 gm. of silage were dried to constant 
weight, in most cases in a vacuum oven at 6o° C. 
1 The oxidizing solution used was made up in the following proportions: 10 gm. of potassium dichromate 
(Ka Cra O7), 20 gm. of sulphuric acid (Ha SO4), 70 gm. of water. 
