TOXICITY OF HEAVY METALS 59 



peas. Other cases of antagonistic salt action in combinations of salts 

 of the alkali metals or of the alkaline earths have been demonstrated, 

 and some information has been obtained regarding the influence of 

 these salts on the effect of the heavy metals, which seem to be 

 universally toxic. The latter have not received much attention, however, 

 and it seemed worth while to investigate some of these, alone and in the 

 presence of calcium and magnesium, to obtain evidence as to whether the 

 lighter metals may modify in any way the toxicity of the heavy ones. 

 The investigation described in this paper was accordingly undertaken. 

 The problem here involved will be taken up more in detail after some of 

 the literature pertinent to the subject has been considered. 



One of the earlier studies of the influence of chemical compounds upon 

 the toxicity of the heavy metals was carried out by Kronig and Paul. 7 

 These authors determined the effects of various heavy metals in com- 

 bination with many salts as well as with certain acids and bases. Mainly 

 from work with Bacillus anthracis, they regard the influence of other 

 halogen compounds upon the toxicity of mercuric chloride as probably 

 due to a depression of the ionization of the latter salt. In this connection 

 they say (page no): " Die Desinfectionswirkung wasseriger Mercuri- 

 chloridlosungen werden durch Zusatz von Halogenverbindungen der Metalle 

 und von Salzaure herabgesetzt. Es ist wahrscheinlich, dass diese Vermin- 

 derung der Desinfectionskraft auf einer Riickdrangung der elektrolytischen 

 Dissociation beruht." 



Clark 8 carefully studied the influence of various concentrations of 

 sodium chloride upon the toxicity of mercuric chloride as regards the 

 process of germination in various fungus spores and seeds and that of 

 growth in yeasts and bacteria. He found that the toxicity of a mercuric 

 chloride solution increased with addition of small quantities of sodium 

 chloride but decreased when high concentrations of the sodium salt 

 were used. He explained these phenomena by considering that a double 

 salt of sodium chloride and mercuric chloride was formed, such as 

 Na 2 HgCl 4 or some similar combination. He supposed that the dissociation 

 tension of this double salt was probably much higher than that of mercuric 

 chloride, a consideration which might account for the increased toxicity 

 of combinations in which small amounts of sodium chloride were employed. 

 In this connection, he suggested that the HgCl 4 ion present when such a 

 salt as Na 2 HgCl 4 dissociated at lower concentrations, might be considerably 

 more toxic than the HgCl 2 molecule to which he seems to attribute the 

 toxicity of mercuric chloride solution. 



7 Kronig, B., and Paul, Th., Die chemischen Grundlagen der Lehre von der Giftwirkung und Desin- 

 fection. Zeitsch. Hygiene und Infectionskrankheiten 25: 1-112. 1897. 



8 Clark, J. P., On the toxic value of mercuric chloride and its double salts. Jour. Physic. Chem. 

 5: 289-316. 1901. 



