12 
Journal of Agricultural Research 
Vol. XXV, No. z 
volume and tested for lactic acid by the Kelling ferric chlorid test and by 
Uffelmann’s test, both of which gave positive reactions. The remainder 
of the liquid was placed in a test tube fitted with a conducting tube 
leading to a second test tube containing i cc. of water. On heating 
the material in the first tube it decomposed, giving off white vapors, 
which were absorbed by the water in the second tube. This material 
when boiled with 5 cc. of 10 per cent sodium hydroxid became first 
clear-yellow, then turbid, opaque and yellow-orange, giving a pene¬ 
trating characteristic odor, thus confirming the previous tests for lactic 
acid. 
The residue of barium salts of nonvolatile acids remaining undis¬ 
solved after trituration with the 10 to 12 cc. of water, as indicated in 
the preceding paragraph, was dissolved in 50 cc. of hot water and decom¬ 
posed with sulphuric acid. Any trace of excess acid was avoided. The 
material was concentrated on the steam bath to 10 cc., filtered into a 
weighed test tube, and evaporated to dryness on a steam bath while 
removing the vapors by an air current through a piece of glass tubing 
inserted in the neck. The dried residue of about .05 gm. was heated 
for 30 minutes with .3 gm. of p-toluidin in a bath at 210° C., employing 
a reflux air cooler. After cooling, 5 cc. of 50 per cent alcohol were 
added, and then it was boiled, thoroughly cooled, and filtered. The 
crystals obtained were dissolved in 5 cc. of alcohol and recrystallized 
on a watch glass. White needle crystals, presumably succintoluid, 
separated out, but the yield was almost microscopic in volume and too 
impure, as shown under the lens, to employ in a melting point deter¬ 
mination. The precipitate filtered from the 90 per cent alcohol solu¬ 
tion was also tested as outlined above for succinic acid but without posi¬ 
tive results. The evidence obtained therefore indicates the presence 
of a trace of lactic acid and perhaps also succinic acid. 
In order to make sure that the products identified were not the 
result of the activities of bacteria or other secondary organisms fol¬ 
lowing the fungus, the work was repeated with substantially identical 
results, employing both sweet potato broth and sterilized sweet potatoes 
in flasks, as well as raw blocks of sweet potato cut from the tubers under 
aseptic conditions and placed in sterilized flasks. Raw sweet potato 
juice secured by grinding sound tubers of the same variety as those 
used in the inoculation experiments and subjecting the pulp to pres¬ 
sure in the meat press yielded a neutral distillate free from ammonia. 
SUMMARY 
It may be concluded that the fermentation produced in sweet potatoes 
decaying through the action of Rhizopus tritici is of the familiar alcohol- 
acetic acid type, in which, in addition to alcohol and acetic acid, much 
smaller amounts of formic, butyric, lactic, and succinic acids are found, 
as well as acetone and an unidentified aldehyde, and that ammonia is 
among the nitrogenous decomposition products. 
