H. L. Wells — Discussion of Triple Salts. 27 



Art. III. — A Discussion of Triple Salts; by Horace 



L. \Yells. 



[Contribution from the Sheffield Chemical Laboratory of Yale University.] 



The object of this article is to present a few points in 

 regard to triple salts, particularly in connection with the 

 regularity and irregularity of their types, without 

 attempting to give a complete list of those that are known, 

 or to discuss them fully. 



There are many instances where analogous triple salts 

 are known, and in some cases these occur in rather exten- 

 sive series, but there are a great many cases where anal- 

 ogy is lacking between salts of analogous metals, so that 

 there appear to be no definite laws, based upon the 

 valency or other characters of the constituent salts, 

 according to which they appear to be formed. A similar 

 conclusion was reached by the writer 1 in connection with 

 a discussion of double halogen salts. 



To give examples, the triple chlorides recently 

 described by the writer, 2 



Cs 4 Ag 2 Au 2 Cl 12 , Cs 4 Au' 2 Au"' 2 Cl 12j 



Cs 4 ZilAti 2 C1 123 Cs 4 HgAu 2 Cl 12 , 



Cs 4 CtiAu 2 C1 12 , 



show analogous formulas and isomorphism, even where 

 two atoms of a univalent element and one of a bivalent 

 element replace each other, but Pollard's salt, 3 (XHJ 6 Ag 2 

 Au 3 Cl 17 , fails to agree with them, as do also two triple 

 bromides, 



KFe"Fe'",Br .3H,,0 and RbFe' / Fe" , 2 Br 9 .3H 2 0, 



described in this laboratory by Professor P. T. vTalden, 4 

 although, in this case, there are agreements in the valen- 

 cies of the metals. 



Among the considerable number of triple thiocyanates 

 described by the writer and his associates, 5 many analo- 

 gous salts were found, but the number of types that 



1 Amer. Cliem. Jour., 26, 389. 



2 This Journal, Mav, 1922. 



3 This Journal, April. 1922. 



4 This Journal, 48, 283, 1894. 



5 H. L. Wells, O. G. Hupfel, H. F. Merriam, C. S. Leavenworth, R. T. 

 Roberts, Amer. Chem. Jour., 28, 245; P. L. Shimi and H. L. Wells, Ibid., 

 29, 474; H. L. Wells, Ibid., 30, 144.] 



