Medical Jurisprudence And Toxicology

CARBON DIOXIDE 737

A male child, 4 months old, was shut up in a small steel trunk on or
about the 29th November 1930, and died consequently. At the post-mortem
examination held by me on the next day the face was flushed, and the lips
and finger-nails were cyanosed. The mucous membrane oŁ the larynx and
trachea was congested and covered with froth. The lungs were congested
and exuded frothy blood from the cut surfaces. The liver, spleen and kid-
neys were congested.

Tests.—1. Carbon dioxide makes lime-water milky.

2. A burning candle will be extinguished in an atmosphere containing
about 15 to 16 per cent of carbon dioxide.

3. Barium nitrate gives a white precipitate of barium carbonate with
carbonic acid, soluble with effervescence in hydrochloric or nitric acid.

4. Silver nitrate gives a white precipitate of silver carbonate.

• Medico-Legal Points.—Cases of poisoning by carbon dioxide are mostly
accidental. In his annual report for the year 1941, the Chemical Examiner,
Bengal, reports the case of two men, who died of asphyxia from the inhala-
tion of carbon dioxide in a 36 feet deep well having 4 feet oŁ water. One of
them went down into the well to recover his bucket dropped accidentally.
He was soon found in great distress at the bottom of the well; hence the
other man went to his rescue, and got down promptly into the well. He
felt suffocated, and raised an alarm at once, but neither of them could be
brought out of the well in time, and both died.

CARBON MONOXIDE (CARBONIC OXIDE GAS), CO *

This is prepared by the decomposition of certain organic substances,
such as oxalic and formic acids, by means of sulphuric acid, and is formed
whenever carbon is burned with an insufficient supply of air or oxygen. It
is found in the gaseous products from charcoal stoves, salamanders, blast
furnaces, lime kilns, gas engines and burning houses. It is generated in a
large amount when gunpowder or dynamite is exploded, and when explosions
occur in coal mines. It is a constituent of coal gas, the amount varying from
4 to 15 per cent. It is found in the proportion of 30 to 40 per cent in water
gas which is obtained by blowing steam through red hot coal or coke. It is
present in quantities varying from 6 to 9 per cent in the exhaust gases of
motor cars. The quantity of carbon monoxide produced per minute by a
20 horse-power motor car is approximately 1 cubic foot, which is enough to
render the atmosphere of a small closed garage of 10 by 10 by 20 feet deadly
in less than ten minutes.1 Carbon monoxide also occurs in tobacco smoke.

Carbon monoxide is a colourless, tasteless, inodorous gas. It is almost
insoluble in water and alcohol. It burns with a blue flame, forming carbon
dioxide, and explosive mixtures with air or oxygen. It combines with
metals, such as nickel and iron, and forms colourless liquids, known as
carbonyls. Combined with chlorine, it forms carbonyl chloride, commonly
called phosgene, which was used as a poisonous gas during the last Great
War.

Carbon monoxide is a highly poisonous gas, as it readily combines with
the haemoglobin of the red blood corpuscles to form a stable compound,
known as carboxyhsemo^lobin, and thus reduces the oxygen-carrying power
of the blood. The affinity of carbon monoxide for the blood is about 300
times greater than that of oxygen, so that as long as carbon monoxide is
present in the atmosphere, it becomes fixed cumulatively in the blood.

1. Henderson, Brit Med. Jour., Jan. 9, 1926, p. 44.

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