*95 
decompounding fixed Air. 
45 0 ; that is, too grains of the black matter yielded about six 
ounce measures of this elastic fluid. In other similar experi- 
ments, the quantity of carbonic acid varied from four to seven 
ounce measures in 100 grains of this blackened alkali ; except 
in one experiment, which afforded only three ounce measures 
of the acid, but the largest proportion of charcoal I ever made, 
namely, 12 grains. 
The solution of the above 428 grains was filtered, and the 
residue, which was black, was lixiviated with boiling distilled 
water. This residue, when dried, weighed 32,4 grains; it had 
no taste or smell, but was an impalpably fine, intensely black, 
and very light powder ; for it occupied a one ounce-and-a-half 
measure, therefore, may be estimated to have been about 22 
times lighter than water. A little of this black powder, be- 
ing thrown upon a red hot iron plate, ignited readily, but 
leYt a residue, which was one-fourth of its weight : this being 
again thrown upon the red hot iron plate, it ignited, and there 
remained, on cooling, a very small portion of brownish powder, 
which diminished to almost nothing, by being applied twice 
more to the iron kept red hot for several minutes. On 
sprinkling this black powder upon boiling nitre, it sparkled 
most brilliantly and detonated, leaving a colourless mass en- 
tirely soluble in water. This black powder, mixed with 
powdered nitre, deflagrated on exposure to heat, in a retort 
with the air-apparatus affixed to it, affording, over quicksilver, 
carbonic acid. This black matter, also, reduced the calx of 
lead ; being mixed with tartar of vitriol, and heat being ap- 
plied, hepar sulphuris was produced ; and with phosphoric 
acid, phosphorus was obtained. That, therefore, these 32,4 
grains were charcoal, cannot, I think, be doubted. I might 
