174 Journal of Agricultural Research voi. xix, no. 4 



Immediately after the jars were filled a sample of the original chopped 

 corn was examined. Thereafter a jar of the silage was opened and 

 examined on the second, fourth, sixth, eighth, twelfth, eighteenth, 

 twenty-ninth, forty-fourth, sixty-sixth, and ninetieth days. Determina- 

 tions were made for moisture, total acidity, alcohol, total sugar, and 

 starch. As a matter of expediency, qualitative tests were made for the 

 transitional products of starch hydrolysis, namely, soluble starch and 

 dextrins. 



Although similar data upon total acidity, alcohol, and sugars have been 

 published, this work was repeated because the amount of these products 

 varies so widely in silage made of corn from different sources that 

 correlation with starch changes in this silage would be impracticable. 

 Furthermore, the determinations serve to show that fermentation was 

 normal; and when arranged in series to show changes beyond the first 

 month, they may furnish information not available hitherto. 



METHODS OF ANALYSIS 



Determinations of constituents soluble in water were made in cen- 

 trifuged and filtered juice pressed from 2 kgm. of the silage with an 

 hydraulic press. 



Moisture. — Four hundred gm. of silage were oven-dried at 100° C. to 

 constant weight. 



ToTAiv ACIDITY. — Twenty-five cc. of silage juice were diluted to volume 

 in a loo-cc. graduated flask with neutral 95 per cent alcohol, mixed 

 and filtered. A 50-cc. aliquot was pipetted into about 300 cc. of neutral- 

 ized distilled water and titrated with Njio barium hydroxid and phe- 

 nolphthalein indicator. 



Alcohoi^. — The aeration method of Dox and Lamb (4) was used. 

 Twenty-five cc. of silage juice in a loo-cc. cylinder, saturated with am- 

 monium sulphate, were aerated by aspirating air for 24 hours through 

 the alcoholic solution from a dichromate oxidizing solution and through 

 tv/o cylinders, the first containing about 18 cc. and the second about 

 8 cc. concentrated sulphuric acid. The sulphuric-acid alcohol solution 

 was then transferred to a 500-cc. distilling flask with water free from 

 carbon dioxid, and after the addition of 5 gm. sodium dichromate, it was 

 distilled through a Hopkins trap. The distillate was titrated and the 

 weight of alcohol calculated from its acetic-acid equivalent. 



Sugars. — Determinations were made in preserved samples of the 

 juice. Seventy-five cc. of silage juice were neutralized in a 1 50-cc. 

 graduated flask with calcium carbonate and made up to volume with 

 absolute alcohol and stored. Of this mixture 100 cc. were diluted to 

 volume in a 250-cc. graduated flask with 95 per cent alcohol. From 

 this point the alcohol extraction method published by Bryan, Given, 

 and Straughn (j) was followed, and sugar was determined by the copper 

 method of Munson and Walker. 



