420 
POISONOUS EFFECTS OF CARBONIC OXIDE. 
tained that one per cent, of the gas in atmospheric air would 
kill a small dog in a minute and a-half, and that birds were 
killed immediately in a mixture containing five per cent, of it. 
Very recently I have myself ascertained that air containing 
only 0*5 per cent, of the gas will kill small birds in about 
three minutes ; and that a mixture containing one per cent, 
of the gas will kill in about half this time. An atmo¬ 
sphere having two per cent, of the gas will render a guinea-pig 
insensible in two minutes ; and in all these cases the effects are 
the same. The animals show no sign of pain; they fall in¬ 
sensible, and either die at once with a slight flutter,—hardly 
amounting to convulsion,—or they gradually sleep away as if 
in profound coma. The post-mortem appearances are not 
very striking: the blood is a little redder than usual, the 
auricles are somewhat gorged with blood, and the brain is a 
little congested. In birds there is nearly always effusion of 
blood in the brain, and it may be seen through the trans¬ 
parent calvaria by merely stripping off the scalp after death. 
Accident has also demonstrated how injurious the gas is 
even to the human subject. For many years past attempts 
have been made to promote the use of water-gas as an agent 
of illumination. The gas sometimes contains as much as 
thirty-four per cent, of carbonic oxide. It is obtained by 
passing steam over red-hot charcoal; and as the steam is 
decomposed by the ignited carbon, the hydrogen is set free, 
and carbonic oxide, with carbonic acid, is produced. Patents 
for this process of manufacturing gas date as far back as the 
year 1810, and they have at various times been put into opera¬ 
tion in this country and on the Continent. Sellique, in 1840, 
obtained permission to use the gas in the towns of Dijon, 
Strasburg, Antwerp, and two of the faubourgs of Paris and 
Lyons. At Strasburg an accident occurred which put a 
stop to its use. The gas escaped from the pipes into a baker's 
shop, and was fatal to several persons; and not long after an 
aeronaut, named Delcourt, incautiously used the gas for 
inflating his balloon. He was made insensible in the car, and 
those who approached the balloon to give him assistance 
fainted and fell likewise. The use of the gas has, therefore, 
been interdicted on the Continent. 
Another source of danger from it is in the combustion of 
carbon. It is found in the neighbourhood of brick-kilns and 
furnaces. The gases discharged from the latter contain it in 
large proportion. Iron furnaces produce it to the extent of 
from twenty-five to thirty-two per cent., and copper furnaces 
from thirteen to nineteen per cent. In the year 1846, M. 
Adrien Chenol was anxious to ascertain the properties of the 
