502 Professors KirchhofF and Bunsen on Chemical 



g. Neutral Sulphate ofCcesium. 



The aqueous solution of this salt possesses an insipid taste, 

 but a bitter after-taste. It is far more soluble in water than the 

 corresponding potassium-salt. 100 parts of water take up at. 

 ^-2° C. not less than 158*7 parts of sulphate of caesium, whereas 

 only 8 - parts of sulphate of potassium are dissolved under similar 

 circumstances. When the aqueous solution is allowed to evapo- 

 rate slowly over sulphuric acid, small, irregularly formed, hard 

 crystals are deposited, which generally are found to have the form 

 of short flattened prisms, and often occur grouped together in 

 irregular, masses. The crystals are anhydrous, quite unaffected 

 by exposure to air, and insoluble in alcohol. We, have not suc- 

 ceeded in obtaining any individual crystals suitable for mea- 

 surement. 



The analysis of the salt was made by converting the carbonate 

 into the sulphate. For this purpose 07921 grrn. of fused car- 

 bonate of caesium was treated with sulphuric acid, and yielded 

 0-8828 grm. of fused sulphate. Hence the composition of the 

 salt is — 



Calculated. Found. 



CsO ... 131-35 76-6Q 76-85 



SO 3 ... 4000 23-34 23-15 



171-35 100-00 10000 



With the sulphates of cobalt, nickel, magnesium, &c, sulphate 

 of caesium produces a series of beautifully crystallizing double 

 salts, containing 6 atoms of water of crystallization, and isomor- 

 phous with the corresponding salts of potassium and rubidium. 

 The following faces were observed in these crystals : — 



OP . ooP . +P . [P oo] . +2Poo . ooP2. 



The sulphate of caesium also forms with sulphate of alumi- 

 nium a double salt containing 24 atoms of water, and crystalli- 

 zing in the regular system, corresponding exactly to potassium 

 and rubidium alums. 



h. Chloride of Caesium. 

 By neutralizing the carbonate with hydrochloric acid and 

 evaporating the solution, chloride of caesium is obtained in the 

 form of small anhydrous indistinct cubes. When quickly cry- 

 stallized, the salt appears, like sal-ammoniac and chloride of 

 potassium, as a mass of feathery crystals. Chloride of caesium 

 fuses at a low red heat, and volatilizes at a higher temperature 

 much more easily than chloride of potassium, in the form of white 

 vapours. The fused salt, on cooling, assumes the form of a 

 white opake mass, which rapidly absorbs moisture from the air 



