274 IT. L. Wheeler — Double Halides of Tellurium 



Strong hydrochloric acid separates potassium chloride. It 

 therefore cannot be precipitated from its solutions by the addi- 

 tion of strong hydrochloric acid, as in the case of the other 

 chlorides. Alcohol also separates potassium chloride. Water 

 apparently effects the same decomposition as in the case of the 

 caesium and rubidium chlorides. The tendency of potassium 

 chloride to separate along with the salt explains why Rammels- 

 berg's analysis came high in regard to the potassium chloride. 

 His results corresponded to a mixture of two molecules of KC1 

 and three molecules of 2KC1 . TeCl 4 . Experiments with the 

 calculated quantity of the constituents invariably resulted 

 in the separation of potassium chloride or potassium chloride 

 mixed with the yellow 2KC1 . TeCl 4 . Experiments with 

 the method given by Kamsay* for the preparation of this 

 salt, by mixing aqueous solutions of the constituents, re- 

 sulted in the decomposition of the tellurium chloride, and 

 the resulting white precipitate failed to dissolve until con- 

 siderable hydrochloric acid was added. Attempts to prepare 

 the compound by concentrating the mixture of the con- 

 stituents by the aid of heat invariably resulted in failure. 

 In certain cases, on cooling such solutions, a mass of colorless 

 slender prisms was obtained, which will be described in a 

 future article. 



The Double Bromides. 



The crystals of the anhydrous bromides have a brilliant red 

 color resembling that of the mineral crocoite. The powders 

 of the salts have a color that is similar to that of a mixture of 

 equal parts potassium bichromate and red lead. The powder 

 of the hydrous bromide has the color of mercuric oxide, but, 

 by loss of water, this soon changes to that of the anhydrous 

 salt. 



Ccesium tellurioromide, 2CsBr . TeBi\. — This double halide 

 can easily be prepared by mixing finely divided tellurium with 

 caesium bromide in dilute hydrobromic acid, then adding bro- 

 mine in excess. The presence of free acid is necessary to pre- 

 vent the separation of tellurous acid. When the tellurium has 

 disappeared, the solution is concentrated by the aid of heat, 

 and, on cooling, bright red crystals of the pure salt are depos- 

 ited. These are generally somewhat larger than the crystals of 

 the double chloride. 





Analysis gave : 





Calculated. 



Cs 



30-90 30-87 



30-91 



3054 



Te 



14-29 1360 



14-03 



14-35 



Br ... . 



.. 55-01 



55-32 



55-11 



* loc. cit. 



