with Potassium, Rubidium and Caesium. 273 



being present. Hot water dissolves some of this tellurous 

 acid, and, on cooling slowly, the anhydride separates in the 

 characteristic form of colorless octahedrons. 



Rubidium tellurichloride, 2PbCl. TeCl^ — The preparation 

 of this salt was in every way analogous to that of the caesium 

 tellurium chloride. However, since this salt is far more solu- 

 ble than the corresponding caesium compound, no precipitate 

 was obtained in dilute solutions. The mixture of the hydro- 

 chloric acid solution of the constituents was concentrated by 

 evaporation, and, when cooled, crystals separated. These were 

 in the form of octahedrons, somewhat larger than the caesium 

 salt. 



Calculated for 

 Analysis gave : 2EbCl . TeCl 4 . 



Rb 33-50 33-83 33-59 



Te .- 24-34 24-56 



Gl... 41-85 



This salt remains permanent in the air. From the dilute 

 hydrochloric acid solution, concentrated hydrochloric precipi- 

 tates it unaltered. Water decomposes it, evidently in the 

 same way as the caesium salt. 



Potassium tellurichloride, 2KCI. TeCl±. — To prepare this 

 salt in a pure state an excess of tellurium chloride is necessary. 

 The analyzed material was obtained by spontaneous evapora- 

 tion of the constituents in a solution of dilute hydrochloric 

 acid, twice as much tellurium chloride being present as re- 

 quired by the formula. Under these conditions it was found 

 to separate in the form of light yellow octahedrons, which, 

 under the microscope, were shown to be free from potassium 

 chloride. 



Analysis gave : Calculated for 



Ratio. 2KC1 . TeCl 4 . 



K 17-07 -44 18-79 



Te 30-29 -24 30-03 



CI 49-47 1-39 51-18 



97-13 



The salt, therefore, has the formula 2KC1 . TeCl,. The 

 crystals deliquesce somewhat in moist air and the analyzed 

 material retained a small amount of water, as is shown by the 

 deficiency in the above analysis. It is not probable that the 

 salt contains water of crystallization, for the crystalline form 

 and optical properties show that it is isomorphous with the 

 anhydrous salts. This salt is the most unstable as well as the 

 most soluble of the anhydrous double halides described in this 

 article. It is readily dissolved by dilute hydrochloric acid. 



