HYDROCHLORIC ACID. 
§§ 77, 7 8 -] 
105 
recorded when more than double this quantity has been taken. A girl, 
15 years of age, died from drinking a teaspoonful of the acid. 1 
§ 77. Amount of Free Acid in the Gastric Juice. —Hydrochloric acid 
exists in the gastric juice. This was first ascertained by Prout 2 in 1824 ; 
he separated it by distillation. The observation was afterwards confirmed 
by Gmelin, 3 Children, 4 and Braconnot. 5 On the other hand, Lehmann 6 
pointed out that, as the stomach secretion contained, without doubt, 
lactic acid, the act of distillation, in the presence of this lactic acid, 
would set free hydrochloric acid from any alkaline chlorides. Blondlot 
and Cl. Bernard also showed that the gastric juice possessed no acid which 
would dissolve oxalate of lime, or develop hydrogen when treated with 
iron filings ; hence there could not be free hydrochloric acid, which, even 
in a diluted state, would respond to both these tests. Then followed the 
researches of C. Schmidt, 7 who showed that the gastric secretion of men, 
of sheep, and of dogs contained more hydrochloric acid than would 
satisfy the bases present ; and he propounded the view that the gastric 
juice does not contain absolutely free hydrochloric acid, but that it is in 
loose combination with the pepsin. 
The amount of acid in the stomach varies from moment to moment, 
and therefore it is not possible to say what the average acidity of gastric 
juice is. It has been shown that in the total absence of free hydrochloric 
acid digestion may take place, because hydrochloric acid forms a com¬ 
pound with pepsin which acts as a solvent on the food. The amount 
of physiologically active acid varies with the food taken ; it is smallest 
when carbohydrates are consumed, greatest with meat. The maximum 
amount that Jaksch found in his researches, when meat was ingested, 
was -09 per cent, of hydrochloric acid. It is probable that anything 
above 0*2 per cent, of hydrochloric acid is either abnormal or owing to 
the recent ingestion of hydrochloric acid. 
§ 78. Influence of Hydrochloric Acid on Vegetation. —Hydrochloric 
acid fumes, if emitted from works on a large scale, injure vegetation 
much. In former years, before any legal obligations were placed upon 
manufacturers for the condensing of the volatile products, the nuisance 
from this cause was great. In 1823, the duty on salt being repealed 
by the Government, an extraordinary impetus was given to the manu¬ 
facture of hydrochloric acid, and since all the volatile products at that 
time escaped through short chimneys into the air, a considerable area 
of land round the works was rendered quite unfit for growing plants. 
1 Brit. Med. Journ., March 1871. 
2 Philosophical Transactions, 1824, p. 45. 
3 P. Tiedmann and L. Gmelin, Die Verdauung nach Versuchen, Heidelberg u. 
Leipsic, 1826, i. 
4 Annals of Philosophy, July 1824. 
5 Ann. de Chim., lix. 348. 
7 Bidder u. Schmidt, Verdauungs-Sdfte, etc. 
0 Journal f. prakt. Chemie, xl. 47. 
