"CAUTION IN USE OF MERCUROCHROME-220 SOLUBLE"

To the Editor:  —The communication of Dr. Stolz (The Journal, April 7) seems to call for comment. The salts of organic bases generally exhibit an acid reaction in solution because of a greater or less degree of hydrolysis. It might, therefore, be expected that those salts, when brought into contact with the sodium salt of a comparatively weak organic acid, such as the soluble form of mercurochrome, would act like any other acid and precipitate the dye. I mixed equal volumes of 5 per cent. procain (a hydrochlorid of an organic base) and 2 per cent. mercurochrome-220 soluble. A red precipitate, which soon became gummy, was formed at once, and practically all the dye was thrown out of solution, as indicated by the faint color of the supernatant liquid. Precipitation of mercurochrome was also brought about by cocain hydrochlorid and codein sulphate. As it was thought possible that mercurochrome