THE POPULAR SCIENCE MONTHLY
tions just mentioned would have pronounced the same explanation was to be applied to both, or that the acid in the filtered fluid was the phosphoric.
Additional evidence of the presence of phosphoric acid was believed to be derived from the behavior of the fluid towards solutions of mercury or silver in nitric acid and towards lime water.
The supposed finding of a mineral acid led Young to comment upon the efficiency of metallic iron recommended by Italian physicians as a tonic, its solution being thereby explained. For, he asks, "does not the uniform effects of iron in its metallic state prove that an acid is always present in the stomach?"
The solvent property of the gastric juice on bones and teeth suggested the possibility of its use as a solvent for stone in the bladder.
A calculus was obtained from Dr. Jacobs of a very firm texture weighing exactly fifty grains. It was introduced into the stomach of one of the large frogs. In two days it was taken out for examination: at first sight it was evident solution had taken place, for the gastric juice which adhered to it was coloured with some of the dissolved stone: it was found to weigh forty-five grains. It was forced into the stomach a second time, where it remained for two days; it now weighed thirty-eight grains: from this, it appears, it is well worthy of more attention. When introduced into the bladder, with the heat of the human body, we have little doubt the gastric juice of frogs would act upon calculi with much effect. The fluid is easily procured, and without the necessity, as in other animals, of sacrificing a life every time we wish to obtain it: by means of a teaspoon it is readily brought up from their stomachs.
With the theory of fermentation rejected, the author proceeds to attempt an explanation of the digestive function.
Aliment is dissolved by the gastric menstruum; it then passes into the duodenum and meets with bile and pancreatic liquor; after being united with these, a heterogeneous mass is formed called chyme, and from this the lacteals secrete chyle.
We are Jed to believe this to be the true doctrine, because, as before observed, simple solution will not explain the phenomenon of digestion; nor will the mixture of this dissolved mass, with bile and pancreatic liquor, change it into chyle; for we know chyle is formed when both these fluids are wanting: thus nutrition goes on when the biliary ducts are obstructed, and also when the pancreas is schirrous. That the absorbents have a secreting or digestive power, we learn from the following. Dr. Wistar informs us of a remarkable case, which occurred under his own observation, of a person who was supported for many weeks, by nourishing enemata, alone. Here it can not be said there was bile, gastric and pancreatic liquors to assimilate the injected fluid into chyle; yet chyle was formed and the system nourished. If the lacteals acted the part of simple absorbing, or capillary tubes, their contained fluids ought to partake of the sensible properties of the mass from which they are absorbed. But the reverse of this is the case: chyle has always the same taste, however different the sensible properties of the contents of the intestines may be, whether they are acid, bitter, etc. We draw a strong argument in truth of this opinion, by turning to the vegetable kingdom, throughout the whole of which the digestive process is seated in the absorbents. Water is to them what the fluids of the primæviæ are to the digestion of man: it dissolves their