196 : H. G. SMITH. 
of dilute sulphuric acid was added to the residue in the retort, 
and again distilled. The amount of acid thus obtained was very 
small, and not greater than would probably have been obtained 
if water had been added instead of sulphuric acid. It appears 
from this result, that no volatile acid is present in combination, 
but that it wholly exists in the free state. 
The distillate has a very marked odour of rancid butter, and 
when made alkaline with soda, evaporated to dryness, and treated 
with sulphuric acid and alcohol, the fruity odour given by the 
ethyl butyrate formed by butyric acid under this treatment was 
very marked. 
To determine the rate of distillation of this volatile acid or 
acids, according to the method of E. Duclaux,! 50 ce. were distilled 
in portions of 10 cc. These were then titrated separately, with 
the result that the first 10 cc. required 1-8 cc. of soda solution, 
the second 1:4 cc., the third 1-3 cc., the fourth 11 ec.; and if we 
consider that the acid remaining in the retort would require at 
least 1 cc., we have the following percentages :— 
lst fifth = 27-27 per cent. distilled. 
Sid... 21:31 i = 
ord... .= 19°70 a a 
Mb ce 166i a - 
5th ,, = 15:15 remaining in retort. 
100-00 
Now the rate of distillation for butyric acid does not differ very 
much from these percentages when we consider that only 50 ee. 
could be spared for experiment, while in the original determination 
110 ce. were distilled in a retort holding 250 to 300 ce. 
By adding together the first and second results as given in the 
table, of a distillation of butyric acid, so that they are represented 
as fifths instead’ of tenths, and so on throughout, we have the 
following figures :— 
EDLC LARC SORE a err 
1 Ann. Chem. Phys. [5] ii., 233. 
