hydrochloric acid. The quantities of propionic, butyric, and valerianic
acids respectively which are required to neutralise as much base as
6.25 cubic centimetres of HCl, are in grammes 4.04 of propionic acid,
4.82 of butyric acid, and 5.68 of valerianic acid. It was therefore
judged expedient, in comparing the digestive powers of these acids with
that of hydrochloric acid, to use them in these proportions.
3. Five hundred cub. cent. of a liquid containing about 8 cub. cent.
of a glycerine extract of the mucous membrane of the stomach of a dog
killed during digestion having been prepared, 10 cub. cent. of it were
evaporated and dried at 110o. This quantity yielded 0.0031 of residue.
4. Of this liquid four quantities were taken which were severally
acidulated with hydrochloric, propionic, butyric, and valerianic acids,
in the proportions above indicated. Each liquid was then placed in a
tube, which was allowed to float in a water bath, containing a
thermometer which indicated a temperature of 38 to 40 Cent. Into
each, a quantity of unboiled fibrin was introduced, and the whole
allowed to stand for four hours, the temperature being maintained
during the whole time, and care being taken that each contained
throughout an excess of fibrin. At the end of the period each liquid
was filtered. Of the filtrate, which of course contained as much of the
fibrin as had been digested during the four hours, [page 90] 10 cub.
cent. were measured out and evaporated, and dried at 110 as before.
The residues were respectively
In the liquid containing hydrochloric acid 0.4079 propionic acid
0.0601 butyric acid 0.1468 valerianic acid 0.1254
Hence, deducting from each of these the above-mentioned residue, left
when the digestive liquid itself was evaporated, viz. 0.0031, we have,
For propionic acid 0.0570 butyric acid 0.1437 valerianic acid
0.1223
as compared with 0.4048 for hydrochloric acid; these several numbers
expressing the quantities of fibrin by weight digested in presence of
equivalent quantities of the respective acids under identical
conditions.
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