298 
Proceedings of Boyal Society of Edinburgh. [sess. 
Note on an Analysis of Human Gastric Juice. By 
W. R. Lang, B.Sc., F.C.S., Chemical Laboratory, University 
of Glasgow. ( Communicated by Prof. M‘Kendrick.) 
(Read March 15, 1897.) 
In the autumn of 1895 I received from Professor M‘Ewen several 
samples of gastric juice marked “ Chalmers’ Gastrostomy.” The 
samples were obtained under most favourable circumstances, being 
drawn off through an aperture made in the abdomen and stomach 
of the patient; the juice was almost pure, and nearly free from 
suspended matter. My analysis was mainly directed towards 
ascertaining whether or not free hydrochloric acid was a constituent 
of the fluid, and the following were the reactions I employed : — 
(1) With methyl violet the sample gave a distinct blue color- 
ation, showing the presence of a mineral acid. Supposing the 
acidity to be due to lactic acid, this reaction would not take place, 
as on trying a dilute solution of lactic acid with this reagent no 
blue colour was produced. 
(2) On treating an alcoholic solution of phloroglucin and 
vanillin (1 grm. of the former and grm. of the latter made up 
with 50 c.c.’s rectified spirits) with the gastric juice and evaporat- 
ing slowly on a water-bath, a red colour was produced. Dilute 
hydrochloric acid gave the same result ; lactic acid none. 
In the opinion of some authorities the presence of free hydro- 
chloric acid is attributed to the decomposition on evaporation of 
the chlorides present in the gastric juice by free lactic acid. With 
a view to ascertain whether this could happen or not, I evaporated 
solutions of chloride of calcium and lactic acid with both of the 
above reagents with a negative result. I also tried solutions of 
chlorides of the alkalies of various strengths with lactic acid 
under similar conditions, but in no case could I detect the slightest 
trace of free hydrochloric acid. These experiments clearly showed, 
therefore, that no such decomposition of the chlorides as was 
suggested could account for the reactions given with the gastric 
juice and the above reagents; and, consequently, the presence of 
free hydrochloric acid in the samples examined is clearly proved. 
