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.