OF COBALT, &c. 



loured fmoke, and thus lofmg its black colour, 

 afliimcd ibon after a grey and nearly metallic 

 appearance. The fmoke was not unlike the 

 vapour which mercury emits. 



A little of this black precipitate, mixed with 

 microcofmic fait, and expofcd to the heat of the 

 blow-pipe, emits a fmokc at the very firit. The 

 precipitate then runs into union with the fait ; 

 yet does not form a globule, unlcfs when a very 

 fmall grain of it is expofed to fire with a particle 

 of the fait. When the proportion of the preci- 

 pitate employed is too large, the mafs alfumes a 

 variety of colours; but if afccond time melted 

 by a flrong blaft of the fire, becomes generally 

 pellucid. The fame thing nearly takes place, if 

 borax be ufed inflcad of microfmic fait ; only the 

 changeable colours do not then make their ap- 

 pearance fo foon. 



The pure liquor remaining after the precipi- 

 tation of the platina and thcfolution of the zinc, 

 was tinged with yellow, and feemcd ftill to retain 

 n little platina ; for when evaporated todryncfs, 

 with the addition of a little vegetable alkali, it 

 a Horded a few yellow grains of refidue. 



The black precipitate is not fubjecl to the at- 

 rniclion of the magnet, cither when newly preci- 

 pitated, or no being expofed to heat- 

 All the metals precipitate platina from aqua 

 rcgia, jull as readily as ?.inc. 



Dd2 111. Prc* 



