“ 
DAMP. 
particularly where it is ane and abounding in Salen 
While it is thus oozing out, it often burns with a quie 
light blue iambent flame, which, on the contaét of a oak. 
explodes ie a bees noife, and, for a time, is extinguifhed 
r force adjacent crevice. In proportion as the 
aan is free off the prodution of this gas diminifhes, 
fo that the dryef& mines are the leaft infeited with it. 
Heat contributes much to its spare ; hence it is 
as it is produced, it foon begins to accumulate in the upper 
part of the galleries, on which account it is a caution well 
worth remembering, by thofe who vifit a coal-pit, to hold 
their candies as low down as pofiible. as thus con- 
tinues to increafe without producing any material incon- 
venience to the miners, till, at ength, it comes in contac 
: the flame is immediately anerealed 
y of gas takes fire: m 
moke darts from the gallery into the ver- 
tical fhafts, whence it rifes into the air with a loud ftunning 
explofion, es up, toa confiderable height, men, large 
cams of timber, and every thing elfe that happens to be in 
its way. oon as the explofion has taken p.ace, the ex- 
‘ternal air roth violently into the mine to fillup the oe 
and the refidual inflammable gas again takes i: and burn 
quietly i a few minutes, till it is extingul 
accident of this kind happens, ee are three 
which the minere within its influence are 
hofe who are in the gallery 
and aré alfo liable to fuffer feverely from the rufhing in of the 
air to fupply the vacuum caufed by the explofion. Secondly, 
thofe who happen to be in the fhaft, or near the mouth of 
the gallery, are either blown up out of the pit, or are 
killed by being violently forced againft its fides. In the 
latter of thefe fituations there is no poffibilicy of efcape ; but 
thofe who are not exploded, often fave their lives by throw- 
ing themfelves on their faces on the ground, and covering 
themielves, as well as they can, with {mall coal, &c. till the 
pat. o particular odour is ee before 
the inflammation, but afterwards a ilrong and eee A 
Imell of oe al hur becomes ee o ue 
We tha “ ea fummary of the fa a8 that were col- 
lected fro ihe. miners by hes flop, as given in the Philo- 
Jophica! "Tran faGiona, N° 
“ Thofe who are in ae lace where the vapour is 
fired, fuddenly find themfelves furrounded with flames, but 
hear little or no noife ; though thofe who are in places ad- 
jacent, or above ground, hear a very greatone. 2. Thofe 
e inflamed vapour feel themfelves 
icorched or burnt, but are not moved out of their places ; 
though fuch as unhappily ftand in the way of it, are com- 
are the heavieft er found able to refift the impetuofity 
mell is perceived before the fire, but a 
very ftrong one of panic is afterwards felt. 4. The 
vapour lies towards the roof, and is not perceived if t 
candles are held low; but when thefe are held higher, the 
damp defcends like a black mift, and catches hold o 
flame, lengthening it to two or three hands full; and this 
eara eafes when candles are held rer the 
und. he flame continues in the vault for feveral 
minutes alter the c lour is blue, fomes 
e 
thing inclining to green, “and very bright. 7. On aaa ek- 
plofion of the — a dark = like that produced from 
firing gun-powder, is se eived. - 8, 
obferved to come abou 
ok fire-damps generally occur in coal-mines; in 
the Philofophical natu ee = 5, we find feveral ac- 
counts and obfervations ma n digg uch mines; and 
a thefe we fhall vompendiouily ps fe, moft ufefal par- 
ticu 
es ae they had gone, the account fays, a confiderable way 
under ground, and were {canted of w - the fire ¢-damps did 
begin by little and little to br eed, aaa appear in crevices 
ane flits of the coal where water had ee before the o ope n- 
ing of the coal, with a {mall blueifth flame, w orking 
moving continually ; but not out of its firft feat, unlefs ihe 
workmen held their candles to it; and the being weak, 
the blaze of the candle would drive it with a fudden ue 
away to another crevice, where it would foon after appear 
blazing and moving as formerly, 
‘This mine was neglected fora certain time; and upon 
morning » the firft cother that went down with Nis candle 
13 
and 
ation of work for fome days, in going down the firft time, 
the fire-damps have often exploded with terrible efieGts,”? 
Tl d effeéts of the fire-damps » ina great meafure, 
not entirely, be prevented by i ee and by a proper 
conformation o excavations, igging a mine, due 
attention ought to.be paid to the roof of it, which ought 
funnel, wiz. having the highe® part of it near to the fhaft 
or fhank; for, by this m 
he oe e gas which always occupies the upper part 
of the mine, may, in that cafe, be exploded with hardly any 
a ne the man. 
When miners are sasaes working in a mine, the acc 
se of the inflammable gas may be cafily prevented, 
%. by firing it off mee as it iffues out of the various 
crevices. 
Ventilation is the niger La a ie removing damps out of 
mines, and at the fame time of giving wholefome air to the 
labourers ; but this is hardly ae in {uch mines as are 
furnifhed with one fhaft o 
nifhed with two or more fhafts in bad a to their extent, 
The ventilation then ma 
The 8 which produces the fire re-damp, a ) 
weil as aren which pioiice, the choke- tie has been i 
quently 
e 
