A rapid method for the determination of gastric acidity by means of test papers was recently described by us.1 Since this description, we have devised a compact indicator set2 for carrying out the method in clinical work.
The apparatus consists of a small wooden case which contains (a) six vials of standard buffer solutions ranging in pH from 3.0 to 1.4, each labeled respectively; (b) a vial of test papers impregnated with thymolsulphonephthalein solution, and (c) a vial of test papers impregnated with dimethylamino-azobenzene solution (Töpfer's reagent).
The hydrogen ion concentration of a sample of gastric contents is determined by pouring a small portion of the unfiltered material over one end of a test paper. From the table of colors in the accompanying tabulation it is then possible to tell at a glance whether the specimen is hyper, hypo, or of normal acidity. A small quantity of