sept. a. 1918 Acidity of Silage Made from Various Crops 
399 
Nonvolatile Acid 
Lactic acid was determined in the juice that remained after distilling 
off the volatile acids under reduced pressure. This solution was evapo¬ 
rated‘on a water bath to a small volume, then extracted with ether in a 
Bremer continuous extractor for 72 hours. After distilling off the ether, 
the acid solution was diluted with water, boiled with an excess of barium 
hydroxid, then exactly neutralized with sulphuric acid. The barium 
sulphate was filtered off and zinc sulphate added to the filtrate, care 
being taken to avoid an excess. After filtering off the barium sulphate, 
the solution was evaporated slowly, the zinc lactate being allowed to 
crystallize. The crystals were filtered off and washed with a small por¬ 
tion of cold water, then dried, and weighed. A second and sometimes a 
third crop was obtained from the mother liquor. 
OPTICAL ACTIVITY OF LACTIC ACID FROM SILAGE 
The combined crops of zinc lactate from each determination were 
examined for their optical activity. A solution containing at least 4 
per cent of zinc lactate in a 2-dm. tube invariably gave a reading of 
zero degrees. Two gm. of zinc-lactate crystals were also dried in an 
oven to determine the water of crystallization. Two gm. of zinc lactate 
gave 0.3635 gm. of water, or 18.17 per cent. 
Theoretical water of crystallization f or zinc-lactate crystals 
Active Inactive 
form. form. 
Water of crystallization. 12. 89 18.18 
Although the 2 gm. of zinc lactate were taken from a combined por¬ 
tion of samples obtained from each silo, it is safe to conclude that the 
zinc lactate was the inactive form. Such results are to be expected in 
silage fermentation where the conditions of inoculation are not con¬ 
trolled. 
EXAMINATION OF SILAGE FROM LARGE SILOS 
Investigations of 1915 
CORN SILAGE 
Although corn silage has been studied and reported by the Iowa 
Agricultural Experiment Station (5, 4, jo), it was thought best to in¬ 
clude corn silage in this investigation. The maturity of the corn is not 
always the same in this country, owing to early frosts, and since maturity 
of corn has been stated by investigators to influence the amount of 
acidity formed, results on acidity of corn produced in Idaho were desired 
for the sake of comparison. The com silage was made from a crop of 
selected Disco Pride corn, cut when the kernels were in the glazed stage. 
The results are given in Table I. 
