144 Prof. B. Moore. On Pree Hydrochloric Acid [Feb. 28, 
of water, administered by the stomach tube, and withdrawn after one and 
a-half hours. The length of time before withdrawal of the test meal is noted 
in each case, in the table. 
The contents before testing were filtered from undigested residues of the 
food, and the tests in all cases were commenced as soon as_ possible 
afterwards. 
The quantitative volumetric testing was performed by neutralising with 
decinormal caustic soda solution, with the indicator mentioned in each case. 
For convenience of comparison the results are expressed in terms of the 
equivalent amounts of hydrochloric acid. But it must, of course, be under- 
stood that in the case of the phenol-phthaléin, and di-methyl-amido-azo- 
benzol indicators, the figures do not represent actual free hydrochloric acid, 
but acidity expressed as the equivalent amount supposing it were all hydro- 
chloric acid. 
(a) Totat Acidity.—This was determined in the usual way by titration of 10 c.e. 
of the gastric contents with phenol-phthaléin as indicator. The amount so obtained 
gives the total acidity due to hydrochloric acid (when present), organic acids, and 
acid salts (such as acid phosphates). 
(b) Acidity to Di-methyl” Indicator.—This indicator does not give as originally 
supposed by its introducer (Topfer),* the free hydrochloric acid alone, but in 
addition, any acidity due to free, strong organic acids, such as acetic, lactic, and 
butyric. Accordingly, this figure is usually higher than that for the free hydro- 
chloric acid given by the other methods described below, and the free hydrochloric 
acid may safely be taken as below the value of this reading. When the organic 
acids are low in value it gives an approximation to the free hydrochloric acid, and 
as it is often used as a clinical method, it is here given for purposes of 
comparison. 
(c) Acidity to Giinzburg’s Reagent? (Phloroglucin and Vanillin).—We have found 
this reagent most reliable, both as a qualitative and a quantitative test. We have 
convinced ourselves by experiment that the test unmistakably shows 1 part of 
free hydrochloric acid in 30,000 parts by volume, and can be relied upon for 
accurate results in rapid clinical work where quantitative results are desired, as they 
always should be. 
The use of the Giinzburg reagent, in conjunction with titration with deci-normal 
alkali, which was first recommended by Muintz,{ was carried out by us as 
follows :— 
Ten c.c. of the filtered gastric contents are taken, two drops are removed with a 
* ‘ Zeitsch. f. physiol. Chem.,’ vol. 19, 1894, p. 104. 
+ Giinzburg, ‘Chem. Centralblatt,’ 1887, p. 1560 ; ‘Centralblatt f. klin. Medicin,’ 1887, . 
No. 40. 
t ‘Wiener klin. Wochensch.,’ 1889, No. 20 ; zbzd., 1891, No. 9. Maly’s ‘ Jahresberichte 
ii. d. Fort. d. Thierchemie,’ vol. 19, 1890, p. 255; zbzd., vol. 21, 1892, p. 222. 
