£58 PURE COBALT. 



Genera! refults.. w j t |, t f ie g Unif which caufes its opacity, and obftru&s its 

 folution in water. It refults at leaft from thefe experiments, 

 that the gums contain, fir ft a calcareous fait, rnoft commonly 

 the acetate of lime ; fecondlv, fometimes a malate of lime 

 with an excefs of acid ; thirdly, pliofphate of lime ; fourthly 

 and laftly, fome iron which is probably alfo united to phof- 

 phoric acid. 



VII. 



Zaffire detonated 

 with charcoal 

 and nitre. 



Tiifion with 

 black Hux. 



The metallic 

 button again 

 detn»ated. 



Lixivhtion 

 feparates the 

 acid and arfenic, 



Nitric acid 

 difioives the 

 cobalt alone. 



Evaporate and 

 rediflblve. j 



Method of obtaining Cobalt pure. Zfy M. Tromsdorf*. 



JT OUR. parts of zaffre well pulverized are to be mixed 

 carefully with one part of nitre, and half a part of charcoal 

 in powder: this mixture is to be projected in (mail quantities 

 into a red hot crucible, and this operation repeated three 

 times, adding each time to the refidue new portions of the 

 nitre and the charcoal. 



The mafs refulling from thefe detonations ought to be mixed 

 with one part of black flux, and expofed during an hour in 

 a crucible to a red heat. 



The whole is then to be left to cool ; the metallic cobalt to 

 be feparated, pulverized, mixed with three times its weight 

 of nitre, and the mixture detonated with the precautions 

 above mentioned. 



The iron contained in the cobalt will thus become ftrongly 

 oxidated, and the arfenic acidified combines with the potafh : 

 The mafs pulverized is to be lixiviated many times, and re- 

 peatedly filtered ; and thus the arfeniate of potafh formed 

 will be feparated from the infoluble refidue that contains the 

 cobalt. , 



This reh\due is then to be treated with nitric acid, which 

 difTbtves the cobalt without attacking the iron which is found 

 oxidated to its maximum of oxidation, 



The folution is then to be evaporated to drynefs, the refidue 

 redifiblved in nitrous acid, and the liquor filtered, to feparate 

 the laft portions of the oxide of iron, which might have 

 efraped in the firft operation. 



* From the Annals de Chimie, Tom. 65. 



All 



