The dictum of Taylor, that a quantity of commercial prussic acid, equivalent to 1 English grain (65 mgrm.) of the anhydrous acid, would, under ordinary circumstances, be sufficient to destroy adult life, has been generally accepted by all toxicologists. The minimum lethal dose of potassic cyanide is similarly put at 2·41 grains (·157 grm.). As to bitter almonds, if it be considered that as a mean they contain 2·5 per cent. of amygdalin, then it would take 45 grms., or about 80 almonds, to produce a lethal dose for an adult; with children less--in fact, 4 to 6 bitter almonds are said to have produced poisoning in a child. § 258. =Action of Hydric and Potassic Cyanides on Living Organisms.=--Both hydric cyanide and potassic cyanide are poisonous to all living forms, vegetable or animal, with the exception of certain fungi. The cold-blooded animals take a larger relative dose than the warm-blooded, and the mammalia are somewhat more sensitive to the poisonous action of the cyanides than birds; but all are destroyed in a very similar manner, and without any essential difference of action. The symptoms produced by hydric and potassic cyanide are identical, and, as regards general symptoms, what is true as to the one is also true as to the other. There is, however, one important difference in the action of these two substances, if the mere local action is considered, for potassic cyanide is very alkaline, possessing even caustic properties. I have seen, _e.g._, the gastric mucous membrane of a woman, who had taken an excessive dose of potassic cyanide on an empty stomach, so inflamed and swollen, that its state was similar to that induced by a moderate quantity of solution of potash. On the other hand, the acid properties of hydric cyanide are very feeble, and its effect on mucous membranes or the skin in no way resembles that of the mineral acids. It attacks the animal system in two ways: the one, a profound interference with the ordinary metabolic changes; the other, a paralysis of the nervous centres. Schönbein discovered that it affected the blood corpuscles in a peculiar way; normal blood decomposes with great ease hydrogen peroxide into oxygen and water. If to normal venous blood a little peroxide of hydrogen be added, the blood at once becomes bright red; but if a trace of prussic acid be present, it is of a dark brown colour. The blood corpuscles, therefore, lose their power of conveying oxygen to all parts of the system, and the phenomena of asphyxia are produced. Geppert[243] has proved that this is really the case by showing, in a series of researches, that, under the action of hydric cyanide, less oxygen is taken up, and less carbon dioxide formed than normal, even if the percentage of oxygen in the atmosphere breathed is artificially increased. The deficiency of oxygen is in part due to the fact that substances like lactic acid, the products of incomplete combustion, are formed instead of CO₂.