In the next place, Magendie and other physiologists have observed that, as in Hufeland's case, the blood and cavities of the body in animals exhale a hydrocyanic odour, even though the quantity taken was small. The blood did so likewise in the heart of the apothecary just mentioned as well as throughout the whole body in the case described in Horn's Journal. The odour, however, is not always present. For example, there was none in the case of another German apothecary, who poisoned himself with an ounce, as recorded in a later volume of Rust's Journal;[1] neither was there any odour in the blood in Mertzdorff's case, although it was strong in the stomach; nor in the blood nor any other part of the body in the Parisian epileptics. It also appears from an experiment by Schubarth,[2] and from a case by Leuret where life was prolonged above fifteen minutes,[3]—that the odour may be distinct in the blood, brain, or chest, when hardly any is to be perceived in the stomach. Schubarth has inquired with some care into the circumstances under which the hydrocyanic odour may, or may not, be expected. He states, as the result of his researches, that if the dose is sufficient to cause death within ten minutes, the peculiar odour will always be remarked in the blood of the heart, lungs, and great vessels, provided the body have not been exposed to rain or to a current of air, and the examination be made within a moderate interval,—for example, twenty-one hours for so small an animal as a dog; but that, if the dose is so small that life is prolonged for fifteen, twenty-seven, or thirty-two minutes, then even immediately after death it may be impossible to remark any of the peculiar odour, evidently because, as already mentioned, the acid is rapidly discharged by the lungs; and that even when the dose is large enough to cause death in four minutes, the smell may not be perceived if the carcase has been left in a spacious apartment for two days, or exposed to a shower for a few hours only. These facts explain satisfactorily why no odour could be perceived in the bodies of the Parisian epileptics; for they lived from half an hour to forty-five minutes. The poison may exist in the stomach, though not appreciable by the sense of smell. In Chevallier's case mentioned above, the contents of the stomach had not any odour of hydrocyanic acid; which, however, was evident to the sense of smell, and plainly indicated by various tests, in the fluid obtained by distilling the contents.
The presence of this odour in the blood may be accounted strong evidence of poisoning with hydrocyanic acid, if it is unequivocal to the sense of several individuals. An exhalation of the same kind is occasionally formed by natural processes in the excrement. Itard once remarked in a case of inflammation of the intestines, and again in a case of inflamed liver, a strong smell of bitter almonds in the fæces, although no medicine containing hydrocyanic acid had been given.[4] Mr. Taylor mentions that he once observed a sort of hydrocyanic odour in the brain of a person who died of natural disease.[5]
