342 Professors Kirchhoff and Bunsen on Chemical 



On treatment with strong alcohol, this mass yielded a residue 

 weighing 65 kilogrammes, which was tolerably rich in csesium 

 salts, and was subjected to a series of processes which will be 

 described under the head of "Residue No. 1" 



To the alcoholic extract from the original mass a concentrated 

 aqueous solution of carbonate of ammonium was added in order 

 to precipitate the greater portion of the lithium-salts. The solu- 

 tion was then evaporated to dryness in an iron vessel and heated 

 to expel all ammoniacal salts, the brown mass (containing much 

 oxide of iron) dissolved in water, and the aqueous solution evapo- 

 rated to dryness. On extraction with alcohol, this salt yielded a 

 residue which we will call " Residue No. 2," to the treatment of 

 which we shall recur. 



This second alcoholic extract gave with bichloride of platinum 

 a yellow precipitate, which weighed 8-5134 grms. after washing 

 with water. The precipitate did not undergo any change of 

 composition on boiling with water ; and when it was placed in 

 the spectrum-apparatus, showed the csesium and rubidium lines 

 with great intensity. It therefore consisted almost entirely of a 

 mixture of the double chlorides of csesium and rubidium, and 

 platinum. 



These 8'5134 grms. =A lost by reduction in a current of hy- 

 drogen 1-8719 grm. = B. The residue contained metallic plati- 

 num, and the neutral chlorides of rubidium and csesium. If we 

 call x the quantity of the double chloride of rubidium and plati- 

 num, and y the quantity of the chloride of csesium* and platinum, 

 we have then 



x + y = A, 



2C1 2 CI 



Pt + Rb + 3C1* + Pt + Cs + 3C1 2/ ; 

 hence we find 



# =35-4975 B- 7*65588 A, 

 y= 8-6559 A- 35-4975 B. 

 By substitution of the values of A and B, we have the following 

 as the composition of the precipitate : — 



Double chloride of platinum and csesium . . 1-2701 

 Double chloride of platinum and rubidium . . 7*2433 



8-5134 

 Hence 100 parts of the alkaline chlorides, combined with the 

 chloride of platinum, are composed of — 



Chloride of csesium . . . 16*93 

 Chloride of rubidium . . 83-07 

 100-00 

 * The atomic weight of the csesium is taken to be 123*35, according to 

 determinations which will be found in the sequel. 



