OBSERVATIONS. 63 
veflel in a ftrong heat, till no fmell of 
arfenic could be perceived. This calx 
of cobalt was of a dark brown colour, 
and had loft exactly the third part of its 
former weight. It was melted in a cruci¬ 
ble, with a mixture of two ounces of black 
flux, and one dram of rofin, and covered 
with common fait. A compact regulus 
of cobalt was obtained, which weighed 
1584 grains, after a fmall portion of 34.' 
grains of bifmuth was feparated. The 
fra&ure of this regulus of cobalt was 
of a fine granular texture, interwoven 
with fome tender ftriae, like a net. Small 
pieces were attra&able by the magnet, 
but upon larger ones, fome grains jit 
weight, the magnet had no efte<ft. 
f b) The pulverized regulus of cobalt 
was put by fmall portions into nitrous 
acid, which diffolved it very brilkly; 
the folution was then digefted for fome 
time, diluted with water, and feparated 
by the filtre from the infoluble light 
yellow calx of iron. It was of a brown 
red 
