May 2S. 1914 
Aroma of Hops 
143 
COMPARISON OF THE ACID, ESTER, AND SAPONIFICATION NUMBERS 
OF THE FRACTIONS 
The acid numbers of the fractions during each year are most variable; 
hence difficulty is encountered in attempting a comparison of the oils by 
this means. From the table it is quite obvious that the oils which in their 
original conditions possessed free acidity (as indicated by the high acid 
numbers) show much more decomposition of esters with the liberation 
of free acids than do the oils with less acidity or with none. The acid 
numbers of the fractions of these high-acid oils are in all cases notably 
higher than those of similar fractions of the other oils. It is therefore 
very probable that oils with high acid numbers are much less stable than 
those free from acidity. This may in turn be true of the hops from which 
the oils were distilled. No particular oil appears to show a regular 
increase or decrease in acidity of the fractions, hence it is most difficult 
to draw conclusions from these values. 
