It has been amply demonstrated[91] that pepsin and pancreatin, when in solution, mutually destroy each other; if the solution be acid, the pepsin destroys the pancreatin; if alkaline, the pancreatin destroys the pepsin. By using the characteristic effect of pepsin on proteids in acid medium and that of pancreatin on proteids and starches in an alkaline solution it can readily be demonstrated that commercial liquid preparations labeled as containing both of these ferments actually contain only one ferment. They are misbranded. [91] U.S. Pharmacopeia, 8th revision, p. 334. Besides the liquid a goodly number of solid preparations, chiefly tablets, containing pepsin and pancreatin are offered to the profession. Among these are tablets consisting simply of pepsin and pancreatin. Since pepsin and pancreatin interact only when in solution, it is quite possible to prepare tablets which contain these ferments. The use of such tablets is, however, unscientific, since one or the other of the ferments is destroyed when it comes in contact with the fluids of the digestive tract. In addition to simple tablets containing pepsin and pancreatin only there is at present a host of “digestive tablets” on the market. Among these are some which must be classed with the “digestive impossibilities” (Reports of the Council on Pharmacy and Chemistry, 1910, Vol. 1, p. 41). The preparations referred to are tablets claimed to contain pepsin, pancreatin, diastase, hydrochloric acid and lactic acid. When it is considered that the United States Pharmacopeia defines hydrochloric acid as “a liquid composed of 31.9 per cent. by weight of absolute hydrochloric acid (HCl = 36.16) and 68.1 per cent. of water,” i. e., a solution of hydrogen chlorid, a gas, in water, it would at first appear that the incorporation of any appreciable quantity of hydrochloric acid in tablets would be impracticable. Hydrochloric acid, however, possesses to a limited extent the property of combining loosely with protein substances so that it becomes possible to bring about its combination with pepsin and similar substances to form compounds which are relatively stable at ordinary temperatures. Because of the volatility of the free acid and its limited combining power with protein substances (100 gm. boiled beef combine with 2 gm. absolute hydrochloric acid[92]), the quantity of acid in any tablet can never be large, much less than sufficient to be of any therapeutic value. [92] Hemmeter, Diseases of the Stomach, Edition 3, p. 250. A number of firms offer “digestive tablets” for sale having formulas of which the following may be considered typical: Sacch. Pepsin 4 grains Pure Pancreatin 1 grain Diastase 1/4 grain Aromatic Powder 1/4 grain Lactic Acid 1/8 grain Hydrochloric acid 1/8 grain