Solution Tension and Toxicity in Lipolysis. 261 
give precipitates upon addition to this filtrate. It is possible, how- 
ever, to have a solution so dilute that there is no initial acidity, that 
acid formation will not occur during an incubation period of four 
hours, that the merest opalescence appears on boiling and yet the 
lipolytic activity of the unboiled solution is sufficient to produce from 
neutral ethylbutyrate during an incubation of four hours enough acid 
to require 0.20 c.c. of M-20 KOH for neutralization. Only salts of 
the heavy metals will precipitate anything from a solution of such 
concentration, though the incubation be prolonged to eighteen hours. 
We thus can have lipolytic activity under conditions which allow its 
determination with very pleasing accuracy. 
An aqueous solution is prepared as follows: The weighed quan- 
tity of Holadin is triturated in a mortar with just enough water to 
form a paste. More water is then added, and thorough mixture is se- 
cured by merely rotary motion. If shaken, an abundant froth forms 
which greatly interferes with filtration. The efficiency of the solu- 
tion is decreased by filtration, but accuracy requires a homogeneous 
colloidal condition. All samples were therefore filtered. 
Solutions of toxic salts. — In order to determine the relative toxi- 
city of the various salts with accuracy, it seemed desirable to have the 
same anion in as many cases as possible. The nitrates were selected. 
The nitrate of mercury decomposes with water to form an insoluble 
basic salt so that a substitution had to be made on this account. Just 
how this difficulty was met by Caldwell! is not understood as he re- 
cords the use of both mercurous and mercuric nitrate. For this reason 
I used the chlorid of mercury instead, but with this exception all 
of the salts used were nitrates. Mathews? and McGuigan ° used the 
chlorid of mercury in comparison with the nitrate of silver. Cald- 
well* states that “the nitrates uniformly inhibit the action of the en- 
_ zyme (bromelin) in somewhat greater dilution than the correspond- 
_ ing sulfates and chlorides which agree closely.” The chlorid of 
mercury is not, however, in his list, and this may still be an exception 
to the relation found by him. Kahlbaum’s C. P. chemicals were used 
in all cases except that of lead, which was J. T. Baker’s guaranteed 
purity. Weighings were made from new and original packages: 
Salts not carrying water of crystallization were regarded as anhydrous 
< and weighed as such. The molecular weight of salts containing 
_ Water of crystallization was calculated to include the water. No ab 
; | Loc. cit. 2 MaTHEws: Loe. cit. 
CGUIGAN: Loc. cit. 4 CaLpWELL: Loe. cit., p- 415- 
