the mixture to heat with borax before the blowp' 3 
colour of the globule will be olive green, an lue. | 
small hook of platina wire was use uppo 
the above sin hme and is perhaps one of the. best 
ports employe ‘ é 
The existence of cobalt i in nthe ore sent to you may Re 
he following 
 teadily ascertained in the Way, viz. roast the ore, ~ 
to expel the arsenic; ol yu a of the roasted ore into 
: a watch glass, and cover it nitric ste evaporate to 
dryness, and repeat the operation to convert the iron into 
peroxide 3 on careful evaporation the ech time, a por- 
tion of a peach-blossom coloured or pink coloured residuum 
will be noticed. This is principally nitrate ef cobalt, and 
often forms a circle round the glass: it is deliquescent. 
Now, to a small hook of fine platina wire, srieoh a colour- 
less globule of glass of borax, and on fusing it with a small 
portion of the peach-blossom coloured residuum, the charac- 
teristic bue of cobalt appears. Again, fuse it with a portion of 
oxide of iron; the blue colour disappears, and the peculiar 
greenish hue, which is produced by the fusion of the ore 
itself with borax, is noticed. By the method described 
above, the cobalt existing in less than half a grain of the 
_ Ore may be detected. 
When the crystals of this ming cobalt (for I 
are entitled to call it so now, e it contains 74 p 
of iron,) are digested in dilute Sure Sh: the solution 4 
concentrated, is of arose colour; and the dersseve test* y 
you have recommended, had been tried with all possible 
success; the green sympathetic ink is formed, by the addi- 
tion of . aseuen of common salt tothe nitric solution of 
_ the crysta 
_Itis aetlent that too great reliance has been placed ‘on 
the appearance of the globule of borax, when a doubt has 
existed respecting the presence of rehoil: perhaps many 
crystals now called ‘ ARSENICAL IRON,” from the results of 
fusion with borax, will be found, on farther examination, to” 
Contain cobalt ; and this substance may be eure d to be more 
widely distributed, than it is now supposed to e. Perhaps 
there is no better or easier r method of examination, han that 
tes 
Si 
* Viz, the formation of the green sympathetic ink, 
