Liquor Pepticus

A correspondent asked us if the following mixture should be dispensed with or without a sediment:

To this the late Mr. Benger replied:'I find the prescription yields a clear mixture, which, after standing several days, shows no sign of sediment. Liquor Pepticus (Benger) is slightly acid, and will cause effervescence when mixed with Soda bicarb. It is difficult to see the object of the prescriber in this case, as pepsin and its preparations are practically inert in any but acid media. This mixture is strongly alkaline, and the pepsin would certainly have to wait its turn, till after the soda had been neutralised by the acid contents of the stomach.'

Liquor Sodii Arsenatis

The following mixture yielded in a few minutes after compounding a granular precipitate of strychnine hydrate:

On testing the liq. sodii arsenat. it was found to be alkaline in reaction, and this has been proved to be the normal condition of the solution. Various suggestions have been put forward to account for this (see The Chemist and Druggist, 1899, 11.

1030), but it suffices for the dispenser to know that the solution is alkaline, and that it should be slightly acidified (in this case with dilute hydrochloric acid) before mixing with anything which free alkali may decompose to form a precipitate.

Liquor Strychninae Hydrochloridi

The feeble solubility of strychnine hydrate has been pointed out (pp. 41-2) as a source of danger when solution of strychnine is prescribed in alkaline mixtures. The following are prescriptions in which the strychnine is thrown out of solution: