7 6 POISONS : THEIR EFFECTS AND DETECTION. [§ 45 . 
deepening into coma. It is probably true that charcoal vapour is com¬ 
paratively painless, for when larger amounts of the gas are breathed the 
insensibility comes on rapidly and the faces of those who have suc¬ 
cumbed as a rule are placid. Vomiting, without being constant, is a 
frequent symptom, and in fatal cases the fseces and urine are passed in¬ 
voluntarily. There are occasional deviations from this picture ; tetanic 
strychnine-like convulsions have been noticed, and a condition of excite¬ 
ment in the non-fatal cases as if from alcohol ; in still rarer cases tem¬ 
porary mania has been produced. 
In non-fatal but moderately severe cases of poisoning sequelae follow 
which in some respects imitate the sequelae seen on recovery from the 
infectious fevers. A weakness of the understanding, incapacity for 
rational and connected thought, and even insanity have been noticed. 
There is a special liability to local inflammations, which may pass into 
gangrene. Various paralyses have been observed. Eruptions of the 
skin, such as herpes, pemphigus, and others. Sugar in the urine is an 
almost constant concomitant of carbon monoxide poisoning. 
§ 45. The poisonous action of carbon monoxide is, without doubt, 
due to the fact that it is readily absorbed by the blood, entering into a 
definite chemical compound with the haemoglobin ; this combination is 
more stable than the similar compound with oxygen gas, and is therefore 
slow in elimination. 
Hence the blood of an animal remaining in an atmosphere containing 
carbon monoxide is continually getting poorer in oxygen, richer in carbon 
monoxide. Grehant has shown that if an animal breathes for one hour 
a mixture of 0-5 carbon monoxide to 1000 oxygen, the blood contains at 
the end of that time one-third less oxygen than normal, and contains 
152 times more carbon monoxide than in the mixture. An atmosphere 
of 10 per cent, carbon monoxide changes the blood so quickly, that 
after from 10 to 25 seconds the blood contains 4 per cent, of carbon mon¬ 
oxide, and after from 75 to 90 seconds 18-4 per cent. . Breathing even 
for half an hour an atmosphere containing from 0-07 to 0-12 per cent, 
carbon monoxide renders a fourth part of the red corpuscles of the blood 
incapable of uniting with oxygen. 
The blood is, however, never saturated with carbon monoxide, for 
the animal dies long before this takes place. 
The characteristics of the blood and its spectroscopic appearances 
are described at p. 68. 
Besides the action on the blood there is an action on the nervous 
system. Robert, 1 in relation to this subject, says :—“ That CO has a 
direct action on the nervous system is shown in a marked manner when 
an atmosphere of oxygen, with at least 20 per cent, carbon oxide, is 
breathed ; for in the first minute there is acute cramp or total paralysis 
1 Lehrbuch der Intoxicationen, p. 526. 
