F. Walter found that in different animals of the same species, the action of the acid was different; from 7 to 8 grammes of hydrochloric acid per kilogramme of body-weight might be given to a rabbit in one day without necessarily serious result, but if the proportion of 9 grammes in the same period were exceeded, death certainly followed within a few hours. The first symptom of poisoning was an increase of frequency in respiration; then the separate breath-movements became deeper and more laborious, with violent heaving of the thorax; the heart beat so quickly that the pulse could not be counted; the animal lost power of moving, and lay quiet on the side for a quarter of an hour before death. The respiration then lost its dyspnoeal character, and grew superficial and weaker as collapse set in, and the heart-action ceased a few moments after the breathing (loc. cit. p. 157). Post-mortem inspection revealed no sufficient change in the organism to account for these symptoms; sometimes, it is true, erosion of the gastric membrane occurred, but the course of the poisoning was not altered in such cases, and therefore it could not be dependent on such erosion: a different concentration of solution, whether 4 or 8 per cent., made no difference in the symptoms; the blood was only so far altered that it coagulated more slowly than usual. It was not found acid in reaction. Hence apparently neutralization of alkali, or withdrawal of some portion of alkali from the blood and tissues, was the cause of death; and this hypothesis was remarkably confirmed by the results of injection of an alkali into the blood-current after full and toxic doses of acid had been given by the stomach. A rabbit that had received more than 6 grammes of hydrochloric acid in three days- three times as much as would kill it - together with 0.2 gramme carbonate of coda injected under the skin with each dose, recovered without loss of appetite or any symptom of poisoning. Another animal received more than 2 grammes of acid, and just when the symptoms indicated the near approach of death 0.5 gramme of soda carbonate was injected into the jugular vein; within ten minutes the strong thoracic movements subsided, the heart-action grew slower and stronger, the animal sat up and began to eat, and in an hour's time seemed quite restored. This direct antidotal action of injected alkali is very striking.

It would seem that the result of diminished alkali in the blood is first a stimulation and then a palsy of the respiratory centre, through which death may be induced. The dyspnoea is not connected with altered heart-action, and the paralysis of respiration must be distinguished from that of asphyxia, for the oxygen contained in the blood remains unchanged.

Synergists

As refrigerant, tonic, and astringent, the other acids; as tonic and digestive, bitters, and also pepsine and possibly pancreatine.

Incompatibles

Alkalies and bases, salts of silver especially. To neutralize irritant poisonous doses of acid, the alkali should be given in mucilaginous or albuminous liquids.

Therapeutical Action (External)