Wells and Willis — Chlorides of Ccesium and Thorium. 191 



Art. XXII. — On the Double Chlorides of Caisium.and Tho- 

 rium ; by H. L. Wells and J. M. Willis. 



^Nearly all of the known double halogen salts of quadriva- 

 lent metals belong to a single type, of which 2KCl'PtCl 4 and 

 2KF'SiF 4 are examples. It has been shown, however, by 

 Marignac* and by Wells and Footef that the double fluorides 

 of zirconium exist in a variety of types. Therefore, since 

 thorium is somewhat closely related to zirconium, we have 

 undertaken an investigation of some thorium double halides, 

 and have selected the caesium salts as being the most prom- 

 ising. 



TJpon attempting to prepare caesium thorium fluorides we 

 found that thorium fluoride is practically insoluble even in 

 concentrated solutions of caesium fluoride containing hydro- 

 fluoric acid. There is no doubt that the two fluorides com- 

 bine under these circumstances, but since we obtained only 

 finely divided precipitates as products and there was no cer- 

 tainty as to their purity, further work on the fluorides was 

 abandoned. ChydeniusJ has previously described two potas- 

 sium thorium fluorides, 2KF-ThF 4 '4H 2 6 and KF'ThF 4 iH 2 0, 

 but on account of the insolubility of thorium fluoride and of 

 these double salts it is probable that there may be some doubt 

 in regard to the correctness of these formulae. 



We have prepared two caesium-thorium chlorides, to which 

 we assign the formulae 3CsCl-ThCl 4 -12H 2 and 2CsCl'ThCl 4 " 

 11H 2 0. The amount of water of crystallization in these com- 

 pounds is somewhat uncertain, since they form very small 

 hygroscopic crystals, and it is difficult to dry them by pressing 

 on paper. The search for double chlorides was made syste- 

 matically by starting with a solution of about 65 g of thorium 

 chloride in hydrochloric acid, adding 2 to 4 g of caesium 

 chloride at a time, and evaporating and cooling after each addi- 

 tion until finally, after dividing the solution and using a part 

 of it, a very large excess of caesium chloride was present. 



In analyzing the salts, chlorine was determined as silver 

 chloride, sometimes in separate portions, in other cases in the 

 filtrates from which thorium hydroxide had been precipitated ; 

 thorium was weighed as oxide after precipitation with ammonia, 

 and the caesium in the filtrates was converted into normal 

 sulphate and weighed as such ; water was determined by dif- 

 ference. 



* Ann. Chim. Pnys. (3), lx, 257. \ This Journal (4), i, 18 ; iii, 466. 



X Pogg. Ann., cxix, 43. 



Am. Jour. Sci. — Fourth Series, Vol XII, No. 69.— September, 1901. 

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