Anthracite Coal of Pennsylvania. ) 335 
ef the carbon touched the glass at once, each gave its distinct 
trace, and thus, in rapidly writing, two or three parallel let- 
ters were produced at the same moment. 
I was thus led to observe whether prepared charcoal would 
seratch the same green glass, and found that it speedily 
spoiled its polish, and a furrows distinguishable by the 
eye and by the finger nail, and perfectly visible by a magni- 
fier. ‘Che same effect, although in a less degree, was pro- 
duced by common charcoal, when the pieces were selected 
from among those made from young and vigorous limbs, and 
the residuum of the coal gas retorts from Glasgow produceda 
similar effect, but by no means so distinctly, as the coak ™ 
which I prepared from the bituminous coal; probably be- 
cause the heat is not pushed so farin the ordinary process 
preparatory to gas illumination. 
The inflammable gas, obtained in the experiments already 
related, stood over water two or three days before | had leisure 
to examine it. I did not remove the carbonic acid, which 
is produced in all such cases, but as there was but little more 
diminution in the volume of the gases in the glass jars, than 
might be presumed to arise from mere cooling—(the gases 
having issued hot from the furnace) and as there was no dis 
coloration inthe water of the cistern, although it was painted 
with oxide of lead, it seems fair to infer that there was not 
much carbonic acid or sulphuretted hydrogen.* For the sake 
* In a subsequent experiment, I washed, with solution of caustic potash, 
a portion of the gas from the Wilkesbarre coal, and found the absorp- 
tion so small that I believe it did not exeeed one fiftieth. I also agitated 
with solution of acetate of lead anocher portion of this inflammable gas 
which had not been washed with alkali, and found that there was not 
the slightest change of colour; there was, therefore, no sulphuretted 
hydrogen and no sulphur of any amount in this anthracite. I burned 2 
jet of this gas in a glass tube half an inch in diameter, and four feet 
long ; it gave distinct musical tones, and lined the tube with innumera- 
ble drops of water, which even ran down in tears. Another portion 
from which the mixed carbonic acid had been removed by washing, 
was burned in a jet, ina quart bottle of common air, which after the 
combustion was ended, precipitated lime water abundantly. 
If there could have been any question as tothe nature of the combus- 
tible gas evolved by heat from this coal, these facts prove, decidedly, 
that it'is nearly pure carburetted hydrogen. Inthe actual combustion ef the 
fuel for use, there will of course be a great amount of carbonic acid, 
and other gases, formed, of which it is foreign to my purpose now to 
speak. Iam not at present, able to account for the great difference in 
