1810.] Correction of Dr. Jones, on the, Danip in Coal Mines. 584 
plosions ensue, and very often the miners 
in the work, and the winders at ,the top, 
of the pit, fall victims to this inevitable 
catastrophe.” All this is so far correct, 
as we too frequently experience in this 
neighbourhood, where hundreds are 
killed by this gas, in a short space of 
time; but unfortunately, the Doctor is 
pot aware, that the miners are annoved 
by two sorts of damps, or airs, viz. the 
inflammable, or hydrogen gas, and the 
carbanic acid gas, or choke damp of the 
miners, formerly known by the name of 
fixed air. Thisis the ‘‘ damp” which the 
Doctor alludes to, when he speaks of 
Lord Cawdor's mines, at Lanlash: ‘ this 
damp rendered the miners heavy and 
sleepy, and made it impossible for them 
to keep in their lights.” This is evi- 
dently carbonic acid gas, or cheke damp, 
for had it been hydrogen gas, or fire- 
damp, as the miners term it, sickness of 
stomach would have occured; and in- 
‘stead of the candles going out, they 
would have exploded the inflammable 
gas. All this is so clear, and so well 
understood, that it requires little trouble 
to detect sucha glaring mistake. This 
error isjust a counterpart to the remedy, 
viz.- by. * slacking lime in the Jevel,” this, 
could not have the least effect upon 
hydrogen gas, or fire damp: and let it 
be understood that the two damps are, 
toto celo, different in their qualities ; the 
one extinguishing a candle, and the other 
being exploded by it, or the candle 
burning in it, the volume of the flame 
being increased, according to the quan- 
tity of the atmospheric air. The Doctor 
proceeds to state, that he requested the 
overseer, “to slacken a few lumps of 
fresh lime in the level, having an idea 
that the carbonic acid gas, produced by 
throwing a few lumps of lime into a little 
water, would correct the air in the works, 
-and make it more favourable to inha- 
Jation, (respiration) and combustion !” 
Ali this is strange enough. I beg leave 
to inform Dr. Jones, that so. far from 
burnt lime “ producing carbonic acid 
gas,” it, on the contrary, absorbs this 
gas in this state: thar it absorbs it 
readily from the atmosphere is well 
known to those who are employed about 
draw-wells; they always observe the 
chemical caution against descending, 
without first lowering a lighted candle; 
ifit burn, they venture down with-safety; 
if not, they let down a guantity of quick- 
lime, in buckets, gradually sprinkled with 
water; as the lime slackens, it absorbs 
the carbonic acid gas, and the atmos- 
pheric air, by its pressure, will supply its. 
place. This property of lime may be 
known to every one by a very familiar 
experiment; expase lime-water to the 
atmospheric air, and it will attract the 
carbome acid gas, and form a crust on 
the surface of the water, which is care 
bonate of lime. Ina word, lime, in no 
state, or manner, can have the least 
etfect upon hydrogen gas, or fire dainp 3 
in small coal-pits, when in q burnt state, 
it may absorb relatively, a little carbonic 
acid gas, but the quantity will be so 
sinall, that in the large mines of this 
neighbourhood, it is never thought of, 
for ventilation is the only agent emplayed 
in these coal-mines. If a current of 
water could be made to flow through 
that part which is most charged with the 
carbonic acid gas, it would carry it aways 
the water absorbing a considerable 
quantity of it, in its course. The choke 
damp is sometimes carried off by a cur- 
rent of atmospheric air, which I have 
observed to be the case in coal-mines, in 
the vicinity of Durham. k 
As to the term explosion, which the 
Doctor “ questions the propriety of,” in 
the note: has he never seen the oxygen 
and hydrogen vases exploded in a 
globe for the formation of water? In this 
experiment he will find that there is con- 
siderable expansion in this process, Let 
him mix two parts of hydrogen gas, 
with one part of oxygen gas; or two parts 
of hydrogen gas, and five parts of ate 
mospheric air; and kindle them ina little 
bottle, or phial, with the mouth upwards; 
when he will find that they will, at the 
instant of explosion, expand and rush 
out of the bottle with the report of a 
pistol: or let the above gases be corked 
and tied down with a bit of leather, ina 
phial, and then fired by an electric spark 
being made to pass through them, he will 
then find that the phial will be blown to 
pieces, and this by the sudden expansion 
of the gases, at the instant of ignition. 
After these experiments are performed, 
Dr, Jones will understand the subject 
better, and will probably allow that there 
is a greater affinity between the science 
and practice of medicine and chemistry, 
than he has hitherto supposed. If phy= 
siclans were better informed in ches, - 
mistry, we should not hear such frequent 
complaints by intelligent apothecaries, 
of the heterogeneous, and incongruous 
mixtures, which they have so frequently 
to prepare for their patients. 
I have only to add, that a discovery 
has recently been made, relative to the 
/ explosions 
