484 
ON THE MEDICAL TOPOGRAPHY OF SINGAPORE. 
cord of suffering ami symptoms, “ affords proof invaluable, that fe¬ 
ver, gangrene and plague, may all result from the same polluted 
air.” According to the tables of Mr. Quetelet, Charcoal Burners 
are within the list of trades where the mortality is sometimes above 
and sometimes below the average rate of mortality. Miners, Bre¬ 
wers, and Lime Burners all breathe an atmosphere much more im¬ 
pregnated with Carbonic Acid Gas then what is to be found in 
marshes, and yet we do not hear of these trades suffering from fever 
more than other trades. 
Carburetted Hydrogen. M. Majendie ascribes to the agency of 
this gas the specific power of marsh miasmata, and quotes a case 
where several persons being asleep the chamber was filled with this 
gas and they were seized with typhus of a very severe form. “ But 
how does this accord with the known effects of Carburetted Hydro¬ 
gen ? When an atmosphere is strongly impregnated with it symp¬ 
toms of narcotic poisoning are produced in those that breathe it; M. 
Devergie mentions that one person was comatose, and occasionally 
convulsed with froth issuing from the mouth, occasional vomiting, 
sterterous breathing, and dilated pupils and in 9 hours he breathed 
his last. But Uysten found it inert when injected into the veins, 
and what is more to the point, Colliers breathe the air of coal mines 
without apparent injury when strongly impregnated with it.” “ The 
mixed gases of coal gas and oil appear likewise to be inert when 
considerably diluted; for gas men breathe with impunity an atmos¬ 
phere considerably loaded with them,” and in the course of some 
researches on the illuminating power and best mode of burning these 
gases, Dr. Turner and myself daily for two months breathed air 
strongly impregnated with them, but never remarked any unpleasant 
effect whatever.”—(Christison.) 
“ Sulpheretted Hydrogen Gas. This is probably the most delete¬ 
rious of all the Gases.”—(Christison.) According to Thenard and 
Dupuytren air containing only an 800th of it will kill small birds in 
a few seconds, a 290th will kill a dog, Champier found a 250th kill a 
horse. Such are the certain effects of the gas when breathed in a con¬ 
centrated state. “ Dr. Turner and I found that Hydro Sulphuric 
