If two drops of phenic acid are diluted with three thousand to five
thousand parts of water, a distinct blue color is produced by one drop
of solution of perchloride of iron.
The addition of six or eight drops of glycerine entirely removes the
color, and if any glycerine was present in the liquid the reaction
does not take place at all. By this test the presence of 1 per cent.
of glycerine can be detected. It may be applied to the analysis of
wines, beers, etc., but when there is much sugar, extractive or
coloring matter, the test can only be applied after evaporating,
dissolving the residue in alcohol and ether, evaporating again, and
then redissolving in water. Alkaline solutions must be first
acidulated.--_Pharm. Zeit. für Russ._
* * * * *