16 BULLETIX 10-34. U. S. DEPARTMENT OF AGRICULTURE. 
and rank all four of them as better than the solvent oils from the 
cake. 
After these opinions had been received the oils were again tested 
in the laboratory, and it 'was found that some deterioration had 
taken place in some of the oils during the five weeks which had 
elapsed since they were deodorized. The bottles containing the oils 
were not quite full and were kept during the interval in a dark 
place. The changes noted were greatest in the oils from the oil 
cake and possibly slightly greater in the benzol-extracted oils than 
in the expeller oils. There seems little doubt that the general quality 
of these oils could have been materially improved with a more 
thorough deodorization. The deodorization of oils in the laboratorv 
on a small scale has certain limitations and can not quite compare 
with commercial operations. The vacuum obtainable in these ex- 
periments was not as great as desired, and the arrangement used 
for raising the oil to the proper temperature might have led to 
unequal heating. It is probable that a more thorough deodoriza- 
tion would not only improve the quality of these oils but would pre- 
vent them from deteriorating rapidly on standing. 
SUMMARY. 
Corn oils obtained by means of expellers and by benzol extraction 
from comparable samples of both dry-process and wet-process corn 
ge rms and oils obtained by benzol extraction from the expeller cake 
were compared as to character and quality. 
Of the crude oils those extracted from the cake were the darkest 
and deposited the greatest amount of sediment on standing. The 
benzol-extracted oils from the wet-process germs contained more free 
acids than the oils obtained by that method from the dry-process 
germs, this being especially true of the oils from the cake. All the 
oils were refined in the same manner, with the exception of the benzol- 
extracted oil from the dry-process germ cake. Owing to the sediment 
present, this oil required a greater quantity of caustic. The oils were 
all deodorized by blowing them with a current of steam at 225 : C. 
(437° F.) for two hours under a vacuum of 25 inches. This treat- 
ment removes odorous volatile constituents and in the case of solvent- 
extracted oils tends to remove the final traces of the solvent. 
The expeller oils showed the lowest loss on treatment with caustic ; 
in the oils obtained by benzol extraction from the germs the loss 
was somewhat crreater. and the benzol-extracted oils from the oil 
cakes showed by far the greatest loss. 
There were no striking differences in the physical and chemical 
constants of the oils either with respect to the two types of germs 
from which they were produced or to the method of production. 
