of Argentiferous Galena. 407 
One hundred grains of the lead cupelled for silver, yielded 
0.27 gr., or 54, lbs. per ton. 
In this assay there was a loss of sulphuret of lead by subli- 
mation ; for, according to its atomic formula, we should have 
obtained, if all the lead was saved, 86 per cent. "This exam- 
ple is sufficient to show how much galena is generally lost in 
the process of reduction. It is rarely the case that we obtain 
more than from 79 to 82 per cent. of lead by reduction, when 
the ore contains 86 per cent. of that metal; but the tempera- 
ture in this operation is so moderate that none of the sulphuret 
of silver volatilizes. 
There is reason to believe that some of the metalliferous ores 
that are fixed in fire have been raised in vapor in combination 
with other materials. Thus, tin may have been raised in 
combination with fluorine, and by decomposition of the fluor- 
ide by water, the oxide of.tin would be deposited, as has been 
suggested by M. Daubrée. 
In other cases, we may suppose one of the elements of a 
Combination to have existed in the rocks, and the other ele- 
ment may have been sublimed, and entered into combination 
With it, as may have been the case in the formation of iron 
Pyrites. Specular iron ore, although oxide of iron alone is 
fixed, owes its origin to the decomposition of the chloride of 
ion; and the oxide rises in vapor and crystallizes on the 
walls of a crevice in the rocks. 
Composition of the bones, tusks and teeth of the Mastodon. 
Although it has long been known that a small proportion 
of animal matter is found in some fossil bones, it has 
until now to demonstrate that the bones, tusks and teeth of 
the American mastodons contain nearly if not all of their car- 
p aginous matter, and that they differ but little from recent 
nes, 
There seems to be some confusion as to the term fossil ; 
“othe supposing that a fossil must necessarily be petrified, or 
