In a previous study of this problem, Tisher (8) showed that the precipitate which appears in the official fluidextracts of uva ursi is invariably crystalline. He described the crystals in considerable detail and suggested that their appearance could be prevented by percolating the drug with menstruums high in alcohol and glycerol content. Tisher also made extensive assays of tannin and arbutin in uva ursi, in fluidextract of uva ursi, and in the precipitate from the latter. He obtained urson and an unnamed gum-like substance from uva ursi but did not study them in detail.
The present paper is a report of our attempts to find acceptable ways of preventing the formation of a precipitate in fluidextracts of uva ursi.
EXPERIMENTAL-EXTRACTION
OF UVA URSI WITH SELECTIVE SOLVENTS.
I n accord with the suggestion of Lloyd (2). and Kelly and Krantz (4) an attempt was made to find a solvent that would extract the principle, or principles, responsible for the precipitation in fluidextract of uva ursi, but which would not, at the same time, remove the constituent, arbutin. QUANTITATIVE EXTRACTION O F UVA URSI.