Prof. Siiliman on the Fusion qf Plumbago, <Sf€, 185 
“ The anthracite of Rhode-Island is thought to be very pure. Dr 
William Meade estimates its proportion of carbon at 9^ per cent. 
This anthracite I have just succeeded in melting by the compound 
blowpipe. It gives large brilliant black globules, not attractible 
by the magnet, but in other respects not to be distinguished from 
the dark globules of melted plumbago.” 
ff I next subjected a parallelepiped of plumbago tp the compound 
flame. It was consumed with considerable rapidity, but presented, 
at the same time, numerous globules of melted matter, clearly, dis- 
tinguishable by the leaked eye ; and when the piece was afterwards 
examined, with a good glass, it was found richly adorned with 
numerous perfectly white and transparent spheres, connected also 
by white lines of the same matter, covering the greater part of the 
surface, for the space of half an inch at and round the point, and 
presenting a beautiful contrast with the plumbago beneath, like 
that of a white enamel upon a black ground.” 
“ In Subsequent trials, upon pieces from various localities, foreign 
and domestic (confined however to very pure specimens), I obtain- 
ed still more decided results ; the white transparent globules be- 
came very numerous and as large as small shot ; they scratched 
window glass — were tasteless — harsh when crushed between the 
teeth, and they were not magnetic. They very much resembled 
melted silex, and might be supposed to be derived from impurities 
in the plumbago, had not their appearance been uniform in the dif- 
ferent varieties of that substance, whose analysis has never, I be- 
lieve, presented any combined silex ; and neither good magnifiers, nor 
friction of the powder between the fingers, could discover the slight- 
est trace of any foreign substance in these specimens. Add to this, 
in different experiments, I obtained very numerous perfectly black 
globules, on the same pieces which afforded the white ones. In 
one instance they covered an inch in length, all around; many of 
them were as large as common shot : and they had all the lustre 
and brilliancy of the most perfect black enamel. Among them 
were observed, here and there, globules of the lighter coloured va- 
rieties. In one instance the entire end of the parallel opiped of 
plumbago was occupied by a single black globule. The dark ones 
were uniformly attracted by the magnet, and I think were rather 
more sensible to it than the plumbago which had been ignited, but 
not melted.” 
Professor Siiliman, in a subsequent trial, found, that Kil- 
kenny coal gave only white and transparent globules ; an effect 
not likely to be produced by impurities, as this anthracite is said 
to contain : 9T per cent, of carbon. In another experiment, 
Professor Siiliman melted a piece of plumbago into two or 
three large limpid globules, and nothing remained qf the original 
appearance qfthe plumbago> but a small number of black points. 
