§ 98. =Action on Human Beings and Animal Life.=--The violence of the action of caustic solutions of ammonia almost entirely depends on the state of concentration. The local action of the strong solution appears to be mainly the extraction of water and the saponifying of fat, making a soluble soap. On delicate tissues it has, therefore, a destructive action; but S. Samuel[118] has shown that ammonia, when applied to the unbroken epidermis, does not have the same intense action as potash or soda, nor does it coagulate albumen. Blood, whether exposed to ammonia gas, or mixed with solution of ammonia, becomes immediately dark-red; then, later, through destruction of the blood corpuscles, very dark, even black; lastly, a dirty brown-red. The oxygen is expelled, the hæmoglobin destroyed, and the blood corpuscles dissolved. [118] Virchow’s _Archiv f. path. Anat._, Bd. 51, Hft. 1 u. 2, S. 41, &c., 1870. The albumen of the blood is changed to alkali-albuminate, and the blood itself will not coagulate. A more or less fluid condition of the blood has always been noticed in the bodies of those poisoned by ammonia. Blood exposed to ammonia, when viewed by the spectroscope, shows the spectra of alkaline hæmatin, a weak absorption-band, in the neighbourhood of D; but if the blood has been acted on for some time by ammonia, then all absorption-bands vanish. These spectra, however, are not peculiar to ammonia, the action of caustic potash or soda being similar. The muscles are excited by ammonia, the functions of the nerves are destroyed. When a solution of strong ammonia is swallowed, there are two main effects--(1) the action of the ammonia itself on the tissues it comes into contact with, and (2) the effects of the vapour on the air-passages. There are, therefore, immediate irritation, redness, and swelling of the tongue and pharynx, a burning pain reaching from the mouth to the stomach, with vomiting, and, it may be, nervous symptoms. The saliva is notably increased. In a case reported by Fonssagrives,[119] no less than 3 litres were expelled in the twenty-four hours. Often the glands under the jaw and the lymphatics of the neck are swollen. [119] _L’Union Médicale_, 1857, No. 13, p. 49, No. 22, p. 90. Doses of from 5 to 30 grammes of the strong solution of ammonia may kill as quickly as prussic acid. In a case recorded by Christison,[120] death occurred in four minutes from a large dose, doubtless partly by suffocation. As sudden a result is also recorded by Plenk: a man, bitten by a rabid dog, took a mouthful of spirits of ammonia, and died in four minutes. [120] Christison, 167.