Solution Tension and Toxicity in Lipolysts. 259 
activity, and by Caldwell! for proteolytic digestion. Mathews an- 
nounced as a general law that the toxic action of cations as such and 
of anions as such is an inverse function of, and is determined by, their 
solution tension. The toxic action of any salt is, then, an inverse 
function of the decomposition tension of that salt which is the sum 
of the solution tension of the cation and of the solution tension of 
the anion of that salt, both values being regarded as having the same 
sign. 
Solution tension is really the affinity of an ion for its charge, and 
may be measured and expressed in volts. Thus mercury, having a 
low solution tension, readily yields its charge to another substance, and 
hence is more potent in disturbing the organization of that substance 
than sodium, for example, which has a high solution tension and is 
consequently relatively inert toward such a substance. Disregarding 
for the present the exceptions observed by Mathews,” it may be noted 
that he based his law upon the fact that when the metals are arranged 
according to their solution tension they are also arranged in the order 
of their relative toxicity toward the eggs of Fundulus. “The same 
general relation was found by McGuigan and Caldwell,‘ as mentioned, 
and so far as I know the validity of the law has never been questioned. 
It may be said that it is a matter of interpretation as to whether the 
experimental data gathered by any one or by all of those men warrants 
such a conclusion. If there were no exceptions (some were found in 
each research) and if the results of the three papers were in perfect 
agreement, would the evidence be conclusive for the law formulated? 
This is merely a matter of logic, and in another form the question is, 
When does circumstantial evidence constitute a demonstration? 
Since the work by those men seems inconclusive, I have attempted to 
remove existing doubt in the matter. In the catalytic saponification 
of esters we have a reaction which can be measured perhaps more 
accurately than any so far tested, and of course more satisfactorily 
than in the case of living organisms. 
The original intention was to extract a lipase from the Castor Bean, 
and then to ascertain the effect of various salts upon the saponifica- 
tion of castor oil by this lipase. Comparative tests with a commercial 
Product (Holadin) having lipolytic power revealed the fact that much 
* CALDWELL, S. J.: Botanical gazette, 1905, xxxix, pp. 409-419- 
? MATHEWs: Loc. cit. 
®* McGuican: Loc. cit. 
- * Catpwete: Loc. cit. 
