48 
It is evident, therefore, from these results that the formates are 
hydrolyzed slightly more rapidly by lipase than the acetates. Work- 
ing with pancreatic lipase under somewhat different conditions Loev- 
enhart and myself found ethyl formate and ethyl acetate to be hydro- 
lyzed with equal rapidity. From the relation which has been found 
to hold for the acetates, propionates, and butyrates, so far as their hy- 
drolysis by lipase is concerned, we might be led to expect that the for- 
mates would be hydrolyzed by lipase somewhat less readily than the 
acetates. The fact that they are not, however, is in keeping with 
other abnormalities displayed by formic acid and its derivatives as 
compared with other acids of the fatty-acid series. 
ETHYL BUTYRATE AND ETHYL ISO-BUTYRATE. 
The rate of hydrolysis of ethyl butyrate and ethyl iso- butyrate by 
lipase has also been determined under the following conditions: Solu- 
tions were prepared containing 10 cc. of N 20 ethyl butyrate and ethyl 
iso-butyrate, respectively, and 5 cc. of a clear solution of lipase. 
These solutions were then allowed to stand at ordinary temperature — 
20° C. — for the desired interval, at the end of which time they were 
titrated with N 50 sodium hydroxide with the following results: 
Time. 
Cubic centimeters N/50 
sodium hydroxide re- 
quired. 
m 
Per cent of hydrolysis. 
Butyrate. 
Iso-buty- 
rate. 
Butyrate. 
Iso-buty- 
rate. 
1 hour 
2.2 
2.2 
8.8 . 
8.8 
3 hours 
3. 65 
4.90 
14.6 
19.6 
5 hours 
5. 10 
5. 90 
20.4 
23.6 
With another specimen of lipase, the other conditions being the 
same as in the preceding, the following results were obtained: 
Time. 
Cubic centimeters N/50 
sodium hydroxide re- 
quired. 
Per cent of hydrolysis. 
Butyrate. 
Iso-buty- 
rate. 
Butyrate. 
Iso-buty- 
rate. 
1 hour _ 
1.85 
3. 50 
1.95 
4. 00 
7.4 
14.0 
7.8 
16.0 
3 hours 
It is evident therefore that there is no marked difference in the rate 
of hydrolysis of these two ethereal salts by lipase. 
Ethyl /?-iodopropionate has been compared with ethyl acetate and 
ethyl butyrate in its conduct toward lipase using N/80 solutions of 
