DAMP. 
hazinefs ee and the air becomes camp; yet fometimes 
ris dryer on account of particular circumftances, 
coke a hazinefs may at firft appear, a perfeé& tranf- 
parency will be reftored foon after. 
It frequently happens, that the vapour which is feparated 
from the air by the oir . co sa remains fufpended in the 
ape of a mift or cloud; other times it defcends im- 
mediately and attache ‘LF . cr bodies in the form 
of dew. But in thefe phenomena the action of eleGricity 
feems to be in oe meafure concerned. We fhall have ocr 
eafion to examine the nature of thofe phenomena more at 
large in other parts of this work. 
The cffects of damp air, damp clothing, and damp apart- 
ments, are varicufly modified by the climate, by the tempe- 
rature, and by the cuftoms of the inhabitants, of every par. 
ticular country. ; 
. noun fubftaitive, (from the Saxon damp, a vapour 
or exha ltion, ) means a a fog, or — air, or moifture; but 
it is principally ufed in the plural, damps, to pre certain 
s or exhalations iffuing from the 
e excavations ; bu 
met rich near the fae of the earth, 
cially in ve cinity of volcanoes. ‘The noxious quali yo of 
fuch exhal ne and the numerous fatal effets which they 
produced, Tee obliged mankind to colle& the various 
ignorance, whof 
rally a the truth in a confiderable proportion of exag- 
geration; yet, from a careful comparifon of thofe very ac- 
Paap ee the refuit of experiments inflituted by {cienti- 
fic perfous, and from the knowledge of the fubje&t of elaf- 
tic fluids, which has, of late years, been wonde;sfully 
for; excepting, indeed, 
are in need either of hidercal Constantin or of a much 
ats nese oes invettigation 
neral effect of the dam mps ig a contamination of the 
common, or relpirable, atmo{pherical alr ; by the admixture, 
not indeed of moifture, as one might be to underitand 
e name of damps, but of other elaftic ids, which are 
abfolutely — for animal refpiration. ic acid gas, 
(formerly called By ile azotic gas, omen eee phlo- 
gifficated rele and Aydrogen gas, or in ‘ammable air, are the 
three elaftic fluids which ele t always, produce 
the damps: we fhall, therefore, biely prem e pa Lae 
pal properties of thefe pe 3 in or t the nature of 
at 
the damps may be underltood toa much eeanleen: 
tion, 
Carbonic acid gas is abfolutely unfit for refpiration or for 
combuition ; animal c 
e deprived of life ne fooner than if he were confine 
under water. ighted candle or torch brou within a 
te 
quantity of this gas, is exting 
hi 
ipped in water is gas is heavier than common air, in 
the proportion of th ; i ce t iffues out 
of the earth in hollow or fheltered places, it remains for a 
confiderable time in a ftrat lofe to the b of the 
place. mone acid gas confifts of 72 parts of oxygen, 
and 28 parts of charcoa 
ae ic — is likewife ‘unfit for refpiration and for 
buflion. Its f{pecific gravity is very little below t 
common air. we is that gas which forms about three- ane 
of the atmofpherical 7 oe other quarter oe prine 
cipally of oxygen air. s pr ae or rather left by it- 
felf, whenever the a n ee the atmofpherical air is ab- 
forbed, as is the cafe in zombuttion, aelpy ation: aad various 
other procefles. 
Hydrogen gas is, by itfelf, utterly unf: for animal re= ” 
{fpiration; but when mixed mmon air, it may b 
breathed with impunity. In its pureft ftate, hydrogen gas 
weighs rather lefs than the twelfth part of an equal bulk of 
common air; but as it is capable of holding in folution wa- 
ter, folphur, phofphorus, carbon, &c. fo its {pecific gravi- 
ty generally exceeds that which has been juft ftated ; 
alwaye, eS much lighter than common air ; ; hence, 
when it occu 
en 
hence, a a ae candle be prefented to a eee quantity 
of h n gas, this will burn either filently and progre{- 
ively, o or r fuddenly, and with an explofion, according as the 
common air is contiguous to one fide of it, or is more.or 
ae aes ly mixed with it. The greateft explofion takes 
la sui ~ en four parts of hydrogen gas are mixed with fix 
of ¢ 
ftance this gas has obtained its name. 
compendious ftatement of the nature aud properties of the 
gafes which produce the damps, we may proceed to defcribe 
the phenomena. 
‘Two forts of damps have been principally defcribed: one 
has been called the cheke-damp, from its fuffocating quality 5 3 
the other has been called the fr ae from its di{pofition 
Aa = fire, and to burn either gently, or with an explo- 
"The choke-damps generally occur in old mines, soe 
uch as formerly had bee 
are ea: frequen 
r fubterranean places whereia the aiv has long re- 
ey are formed by an accumulation 
an 
vith ¢ air. 
elfeets which have ceed ‘produced a this re rt aie te are 
more than cient to manifeft the nature of the gas to 
se it is owing. 
e per ei who happen to defcend within this damp, 
inftantly lofe their refpiration, and fall down fenfelefs ; nor 
can their deat i 
ine, 
continues to 
ing is perfeCtly tafe in in it; but if the candle goes out, then 
the 
