33 



Another theory to account for a similarly decreased 

 toxicity of HgCl2 in the presence of NaCl was advanced by 

 Clark (_1. £. , page ) , who considered that a double salt 

 was formed, such as Na2HgCl4, only slightly dissociated in 

 the presence of an excess of NaCl. This writer also worked 

 with various copper salts in the presence of KNO^, KgSC^, 

 NH0SC4 etc. and suggested that the decreased toxicity of the 

 copper salts which was uniformly observed in such combinat- 

 ions was likewise due to the formation of double salts. 



13 

 In view of the work of Jones and Hosford , - on 



the dissociation of double salts in dilute solution, it seems 

 very improbable that the lowering of the toxicity of 

 Cu(N03)2 brought about by 03(^03)2, as shown in the present 

 study, is due to increased ionization of copper owing to 

 double salt formation. It is, however, possible to obtain 

 direct evidence on this question by comparing the concentra- 

 tions of ionic copper in the various solutions, with and 

 without the calcitim salt. The percentage of dissociation 

 occurring in simple solutions of Cu{K03) has been deter- 

 mined experimentally for many concentrations and these data 

 are available in published tables . From such data may be 



13. Hosford, H. H. , and Jones, Harry C, Conductivity, temper- 

 ature coefficients of conductivity and dissociation of certain 

 electrolytes. Am. Ghem. Journ?, 46:241-278. 1911. 



14. Jones, Harry C, Electrical conductivity etc., of certain 

 salts and organic acids. Pub. 170 Carnegie Institution of 

 Washington. 



