598 Prof. H. E. Armstrong and Mr. H. W. Gosney. [June. 13, 



other hand, we regard the powerful retarding effect of oleic acid as a case of 

 the preferential retardation referred to in the previous communication, this 

 being promoted by the solubility of the acid in the oil ; apparently, it is too 

 weak an acid to interfere as such. 



As it is conceivable that the reduction of the rate of hydrolysis in presence 

 of the acid may be due in part at least to the effect it has in promoting the 

 reversal of the interaction, we have endeavoured to ascertain if the change 

 can be carried to completion by removing the glycerol as it is formed. To 

 this end, the hydrolysis was carried out in a cell constructed by stretching 

 parchment paper over the opening at the narrow end of a small bell-jar. 

 An emulsion of 50 grm. of oil, 20 c.c. of water and 5 grm. of enzyme was 

 placed within the jar, which was surrounded with water ; the oily mixture 

 was constantly stirred by means of a glass stirrer actuated by a fan kept in 

 rotation by means of a small flame. 



After about 24 hours, a curd or clot separated from the mixture and only 

 67'7 per cent, of the oil was hydrolysed after three days. Apparently the 

 enzyme had been either destroyed or in some way modified and rendered 

 inactive. This result was confirmed in a second experiment in which the 

 mixture was kept at rest. 



Observers differ as to the effect of use on lipase. It appears to be easily 

 changed if left in contact with water and this probably is the reason why 

 different preparations differ more or less considerably in activity. The 

 following results may be quoted in this connexion. 



1*5 grm. of lipase powder was shaken up with water and the mixture left 

 at 30° C. during two days in a diffusion thimble immersed in water. As a 

 control, 1*5 grm. of the powder was merely digested with the same volume 

 of water in a flask. Toluene was added in each case. The water in the 

 beaker remained clear during 24 hours but was cloudy after 48 hours. The 

 solid was then filtered off and its action tested as follows. 



A fourth part of each enzyme preparation was added to 5 grm. of oil 

 and portions of the water used for dialysis, etc., as given in the following 

 table, water being added to make up the volume to 18 c.c. in each case :— 



Percentage hydrolysed in 

 24 hours 



1. Untreated acid prepared enzyme 36"3 



2. Enzyme from diffusion thimble 6'1 



3. Ditto + liquid from outside of cell 4 - 6 



4. Ditto + liquid from inside cell 9"1 



5. Enzyme merely digested with water 8*3 



6. Ditto + water with which it had been washed 8'8 



