Fuston of Plumbago. 343. 
from the plumbago could admit of no reasonable doubt. 
1 am now to state other appearances which have excited in 
my mind a very deep interest. On the end of the prepared 
charcoal, and occupying, frequently, an area of a quarter of 
an inch or more in diameter, were found numerous globules 
of perfectly melted matter, entirely spherical in their form, 
having a high vitreous lustre, and a great degree of beauty. 
Some of them, and generally they were those most remote 
from the focus, were of a jet black, like the most perfect ob- 
sidian; others were brown, yellow, and topaz colored; oth- 
ers still were greyish white, like pearl stones with the trans- 
lucence and lustre of porcelain; and others still, limpid like 
flint glass, or, in some cases, like hyalite or precious opal, 
but without the iridescense of the latter. Few of the globules 
upon the zine pole were perfectly black, while very few of 
those on the copper pole were otherwise. In one instance, 
when I used some of the very pure English plumbago, (saw- 
ed from a cabinet specimen, and believed to be from Bor- 
rowdale,) white and transparent globules were formed on 
tne Cope side. 
L-~)j “ J} teh } I 
most, no globules were formed on the | latter, and they were unu- 
ually numerous, and almost all black, on the opposite pole. 
When the points were exchanged, plumbago being on the 
zinc, and charcoal on the copper end, very few globules 
- were formed on the plumbago, and not one on the charcoal; 
this last was rapidly hollowed out into.a hemispherical cav- 
ity, while the plumbago was as rapidly elongated by matter 
accumulating at its point, and which, when examined by the 
microscope, proved to be a concretion in the shape of a-cau-_ 
lidower—of volatilized and melted charcoal, having, in a 
high degree, all the characteristics which 1 formerly deserib- 
ed as belonging to this substance. Indeed, I found by re- 
petitions of the experiment, that this was the best mode of 
obtaining fine pieces of melted charcoal. 
In some instances, I used points of plumbago on both 
poles, and always obtained melted globules on both; the re- 
sults were however, not so distinctas when plumbago was on 
the copper and charcoalon the zinc pole; but the same elon- 
gation of the zinc and hollowing of the copper pole took 
place as before. I detached some of the globules, and part- 
