EXPERIMENTS ON DIGESTION. 
287 
peculiar nature, and have called it “ the gastric acid;" others have 
thought that it was phosphoric acid. Some have imagined it to 
have a relation to acetic or lactic acid; and, more recently, a 
class of chemical philosophers have pretended that it was hydro- 
chloric acid. The result of our experiments is, that it contains se- 
veral acids in a free state. 
1. The Hydro-chloric Acid .* — We have often found this when 
distilling the fluids contained in the stomach, and particularly that 
of the horse, whom, after fasting, we had compelled to swallow 
pebbles. The stomach of a dog, on whom we had forced calcareous 
fragments, contained chloruret of calcium. If this acid was not 
-generally found in distilling the fluids found in the stomachs of 
animals that had been deprived of food, it was, probably, because 
at existed in a very small quantity, and that, retained by some ani- 
mal matter, it could not become volatilized. 
Prout has lately asserted the presence of hydro-chloric acid in 
the stomach of the rabbit, the hare, the horse, the calf, and the dog. 
He, however, is wrong when he says that no other acid has been 
found in the fluid contained in the stomach. Lui and Children 
have found hydro-chloric acid in the liquid vomited by persons 
labouring under dyspepsia. 
2. The Acetic Acid .• — We have found a considerable quantity 
of free acetic acid in the gastric juice of the dog to which we had 
given pepper. We have also found it in the gastric juice of horses. 
A great quantity of it mingled with that of the horse that had been 
forced to swallow pebbles. The lactic acid found by Chevreul in 
the fluid obtained from the stomach of a man that had fasted for a 
considerable time, was nothing else than acetic acid; for it has been 
ascertained, by the recent experiments of Berselius, that the lactic 
and acetic acid are identical. 
3. The Butyric Acid . — We have twice found this in the gastric 
j uice of horses. 
Besides these acids, the gastric juice of animals that have fasted 
contains mucus, but not albumen. At least, we have not found 
this last substance in the dog : but we did once meet with a very 
«mall quantity in the gastric juice of a horse that had swallowed 
pebbles. 
The gastric juice of the dog and the horse contained an animal 
matter insoluble in alcohol, but soluble in water : this was the sali- 
vary matter. 
We also found in both an animal matter soluble in alcohol. This 
was ozmazome. 
The following are the salts which we found on burning the fil- 
tered gastric juice : — 
1. In the dog : — Much chlorine, and a few of the alkaline sul- 
