Analysis by Spectrum-observations. 339 







Calculated. 



Found. 



RbO . 



. . 93-36 



7001 



69-86 



SO 3 . 



. . 40-00 



29-99 



30-14 



133-36 10000 100-00 



With sulphate of alumina this salt forms rubidium alum, 

 RbOS0 3 + Al 2 3 3S0 3 + 24HO, which can be obtained very 

 easily in large, bright, transparent crystals belonging to the 

 regular system. Besides the prominent faces 0, the following, 

 both ooO and goOx , are seen to occur. The crystals are un- 

 alterable in the air, and in other respects closely resemble those of 

 potash alum. 



Sulphate of rubidium also forms with the sulphates of the 

 magnesian class of bases a series of double salts corresponding 

 to the formula KOSO 3 + NiO S0 3 -f 6HO, and isomorphous 

 with the respective potassium salts. These double rubidium salts 

 are more difficultly soluble than the sulphate of rubidium itself, 

 and can be easily obtained in large well-developed crystals. 

 They generally exhibit the following faces : — 



ooP.OP. + P.Pao. + 2Pa>. 



h. Chloride of Rubidium. 



This compound crystallizes indistinctly from aqueous solution 

 upon quick evaporation or cooling; but on allowing the solution 

 to evaporate slowly, cubic crystals are obtained. No other com- 

 bination besides the cubic faces coOco were noticed. The cry- 

 stals are unalterable in the air • they decrepitate on warming, 

 and they fuse when heated to a temperature just below a red 

 heat. Brought into the flame on a platinum wire, the salt 

 volatilizes quickly and completely. 100 parts of water at+ 1°C. 

 dissolve 76-38 parts, and at +7°C. 82-89 parts of this salt. 

 Under similar circumstances 29-47 and 31*12 parts of chloride 

 of potassium are dissolved. 



0-9740 grm. of this chloride of rubidium yielded 1-1541 grm. 

 of chloride of silver, hence the salt consists of — 







Calculated. 



Found. 



Rb . 



. . 85-36 



70-65 



70-30 



CI . , 



. . 35-46 



29-35 



29-70 



] 20-82 10000 10000 



i. Double Chloride of Platinum and Rubidium. 

 ' To obtain this compound a solution of a salt of rubidium is 

 precipitated with bichloride of platinum. 



The precipitate is of a light yellow colour, immediately depo- 



