30 H. L. Wells — Discussion of Triple Salts. 



salts of single metals with three acids, while the last 

 three show combinations with two metals and three acids, 

 and with two of each. 



Enough examples have been given to show that triple 

 salts of analogous metals may have corresponding formu- 

 las in some cases, but that there are many irregularities, 

 leading to a large variety of formulas. Some of the 

 variations depend, as is the case with the Cs-Zn-Ag and 

 Cs-Cd-Ag thiocyanates, upon the proportions of the three 

 simple salts in the solutions from which they are depos- 

 ited, but this appears to be exceptional, since in most 

 cases only a single triple salt can be obtained under such 

 variations. 



A great many of the triple salts show simple numerical 

 ratios in their formulas, but a few of them have undoubt- 

 edly complex compositions. The frequent occurrence in 

 the formulas of 6 and 12 negative atoms or radicals seems 

 worthy of mention as suggesting related molecular struc- 

 tures in such compounds, but there are many varieties 

 of formulas not corresponding to these numbers. 



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