272 II. L. Wheeler— Double Halides of 



tinguished from the other colorless double halides of rubidium 

 and antimony by the fact that it melts at 77°. 



1 : 1 Rtobidium Antimony Chloride, JRbCl.SbCl^ — This 

 salt was first described by Remsen and Saunders ;* they say 

 that " if the excess of antimony chloride ... be very great, 

 a colorless salt crystallizing in elongated, apparently ortho- 

 rhombic, crystals is obtained." I have found that by mixing 

 the constituents in hydrochloric acid solutions, in the propor- 

 tion of four or three molecules of SbCl 3 to one of RbCl, crys- 

 tals of similar appearance were obtained. The solutions 

 require a considerable degree of concentration and the mother 

 liquor is more or less syrupy, hence the rubidium determina- 

 tions came low and the antimony high. Analysis gave : 



From solution From solution Calculated for 



of 4SbCl 3 to lRbCl. of 3Sb01 s to IRbCl. RbCl . SbCl s . 



Rb 23-67 23-96 24*61 



ISb 35-38 34-99 34'53 



CI 40-70 40-73 40-86 



A solution of antimony and rubidium chloride in the pro- 

 portion of 2J molecules of the former to one of the latter 

 gave a mixture of this salt and the yellow one described below. 

 As has been observed by Remsen and Saunders, crystals of this 

 salt rapidly lose their luster on exposure. They give no defi- 

 nite melting point below the temperature of boiling sulphuric 

 acid. 



3:2 Rubidium Antimony Chloride, ZRbCl. 28b Cl 3 — This 

 is the salt to which Remsen and Saunders assign the formula 

 5Rbdl . 3SbCl 3 . They obtained this compound on adding " a 

 considerable excess " of antimony chloride to a solution of the 

 salt 23RbCl. 10SbCl 8 . They describe the crystals as some- 

 times resembling a rhombohedron in general shape and having 

 a pale yellow color, and they remark that u this is noteworthy, 

 because the more complex salt (23RbCl . 10SbCJ 3 ) and the 

 simpler one (RbCl . SbCl 3 ) are both colorless. It is to be 

 remembered, however, that the salt Cs 3 Sb 2 Cl 9 (3CsCl . 2SbCl 3 ) 

 is also yellow." It may be added that both 3CsCl . 2AsCl 3 and 

 3RbCl . 2AsCl 3 are pale yellow. Remsen and Saunders also 

 remark " As the formula of this rubidium salt is not very 

 simple, and as the substance could not be recrystallized, on 

 account of the strong tendency towards the formation of the 

 very complex salt, the formula suggested below can hardly be 

 considered as definitely established." 



* Loc. cit. 



