The pulse is at the onset large, full and frequent; it afterwards becomes small, slow and irregular. The temperature sinks from 1° to 3° C. The respiration at first slow, later becomes rattling. As vomiting occurs often when the sufferer is insensible, the vomited matters have been drawn by inspiration into the trachea and even into the bronchi, so that death takes place by suffocation. The fatal coma may last even when the person has been removed from the gas from hours to days. Coma for three, four and five days from carbon monoxide has been frequently observed. The longest case on record is that of a person who was comatose for eight days, and died on the twelfth day after the fatal inhalation. Consciousness in this case returned, but the patient again fell into stupor and died. The slighter kinds of poisoning by carbon monoxide, as in the Staffordshire case recorded by Dr. Reid, in which for a long time a much diluted gas has been breathed, produce pronounced headache and a general feeling of ill health and _malaise_, deepening, it may be, into a fatal slumber, unless the person is removed from the deadly atmosphere. To the headache generally succeeds nausea, a feeling of oppression in the temples, a noise in the ears, feebleness, anxiety and a dazed condition deepening into coma. It is probably true that charcoal vapour is comparatively painless, for when larger amounts of the gas are breathed the insensibility comes on rapidly and the faces of those who have succumbed as a rule are placid. Vomiting, without being constant, is a frequent symptom, and in fatal cases the fæces and urine are passed involuntarily. There are occasional deviations from this picture; tetanic strychnine-like convulsions have been noticed and a condition of excitement in the non-fatal cases as if from alcohol; in still rarer cases temporary mania has been produced. In non-fatal but moderately severe cases of poisoning sequelæ follow, which in some respects imitate the sequelæ 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. § 39. 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 hæmoglobin; this combination is more stable than the similar compound with oxygen gas, and is therefore slow in elimination.