454 Dandeno — Relation of Mass Action to Toxicity. 



place at all. The only reliable test to the matter is the con- 

 duction of electricity. But this very test may actually bring 

 about dissociation, instead of merely showing that it already 

 exists in the solution. Moreover, the theory of the cause of 

 osmotic action does not throw light upon the matter, as notice 

 the results of Morse and Frazer* on sugar solution — a non- 

 electrolyte. They obtain a pressure of about 32 atmospheres, 

 where, according to the theory of dissociation, it ought to be 

 but 22*6. The high vapor densities of certain substances and 

 the lowering of the freezing point of solutions may be explained 

 on other grounds upon which it is not necessary to enter here. 



The toxicity of compound ions, — those which are composed 

 of more than one element, — has been discussed by Clark and 

 by Kahlenberg and True, but with diverse results. Clark con- 

 cluded somewhat generally that a compound ion was more 

 toxic than a simple ion. The experiments of Kahlenberg and 

 True lead one to the conclusion that the compound ion is much 

 less toxic. They state, referring to such compounds as H 3 P0 4 . 

 that the acid dissociates into H and H 2 P0 4 , and the acid H 3 

 P0 4 is equally toxic with HO. This shows that they consider 

 the H 2 P0 4 ion as practically non-toxic, or slightly so. They 

 state further, referring to potassium silver cyanide, that the 

 complex ion Ag (CN) 2 is far less poisonous than the Ag ion 

 alone. They say also that ferric ions are much more poisonous 

 than are*the complex ions containing ferric iron. Clark, on the 

 other hand, reasoning also apparently from the theory of dis- 

 sociation, referring to H 2 SG 4 states that the ion HS0 4 is 1*3 

 times as toxic as H, and that the whole molecule (HN0 3 ) is 7 

 or 8 times as toxic as the simple ion H. 



]STo attempt is here made to reconcile these statements, for it 

 is impossible to do so. But it shows quite clearly that it is also 

 impossible to reconcile the theory of dissociation with experi- 

 mental evidence. It shows further, that one can not predict 

 just what will be the physiological result if the basis for pre- 

 diction be laid upon the theory of dissociation. 



Another illustration of the danger in attempting to harmonize 

 the theory of dissociation with physiological phenomena, is 

 furnished by a comparison of toxic action between Na 2 S0 4 and 

 NaCl. Cameron places the toxic limit of the former at 3n/400, 

 and True places that of NaCl at n/lQ.-f Now, according to the 

 theory of dissociation (as discussed by Kahlenberg and True), 

 there appears a contradiction ; for, since the anion is a negli- 

 gible quantity in each case, the kation must account for the 

 difference, but the kations are identical. The difference above 

 noted is also too large to be a mere personal difference. Assum- 



* Science, ii, 16, 883. 



f Cameron gives the limit for NaCl at w/50, which is probably correct. 



