Analysis by Spectrum-observations. 343 



Residue No. 2 from the second extraction with alcohol, when 

 dissolved in water and treated with bichloride of platinum, gave 

 a yellow precipitate, which, after being boiled out from ten to 

 twelve times, weighed 23 grms. 13*83 grms. = A of this preci- 

 pitate lost, on reduction in hydrogen, 3*182 grms. =B. Hence 

 the whole 23 grms. consisted of, — 



Double chloride of platinum and csesium . . 11*76 grms. 



Double chloride of platinum and rubidium . . 11*24 „ 



23*00 » 

 100 grms. of the alkaline chlorides contained in the precipi- 

 tate were, therefore, made up of — 



Chloride of csesium . . . 54*89 grms. 

 Chloride of rubidium . . . 45*11 „ 



100*00 » 

 The residue No. 1 weighed 6*5 kilogrammes, and for the most 

 part consisted of the chlorides of potassium and sodium. In 

 order to obtain the caesium-salts still contained in it, the mass 

 was dissolved in water, and the boiling solution precipitated with 

 a quantity of bichloride of platinum amounting to only from 8 

 to 10 thousandths of the weight of the total mass. By boiling 

 out the platinum precipitate fifteen to twenty times with water, 

 and by adding the boilings to the original solution until they 

 become slightly yellow-coloured, a second platinum precipitate 

 is obtained, which must be treated in the same way as the first. 

 The platinum precipitates are thus boiled out until no further 

 deposit of a light-yellow insoluble crystalline mass is observed, 

 and then all the precipitates, thus purified by washing, are re- 

 duced in a current of hydrogen, and the soluble salts extracted 

 with water. The aqueous solution contains a mixture of chloride 

 of csesium and chloride of rubidium. 



A kilogramme of the residue thus treated yielded 1*0348 grm. 

 of such a mixture of the chlorides of rubidium and csesium, from 

 which nitrate of silver precipitated 1*1404 grm. of chloride of 

 silver. Let A 1 signify the mixture of x x parts of chloride of ru- 

 bidium and y l parts of chloride of csesium; and let B 1 signify 

 the weight of chloride of silver obtained from the salt Aj ; we 

 then find the values of x^ and y x from the following equations : — 

 ^ = 3*50963 BJ-3-16906AJ, 

 Vl = 4*16906 A x -3*50963 B r 

 By help of these equations, and of the values of A l and B v it is 

 easy to see that the residue No. 1, weighing 6*5 kilogrammes, 

 contains — 



Chloride of csesium . . 2*0267 grms. 



Chloride of rubidium . . 4*6995 „ 



6*7262 „ 



