The first was the new volumetric method of M. Chandelon
(_Bulletin de la Societe Chemique de Paris_, July 20, 1882; and
_Deutsch-Americanishe Apotheker Zeitung_, vol. iii., No. 12, September
1, 1882), which I have found to be very satisfactory. The process
depends on the precipitation of phenol by a dilute aqueous solution of
bromine as tribromophenol. The second method was to extract, as
already staled, a known weight of each part of the plant with water,
until the last extract gives _no_ violet color with ferric chloride,
and no white precipitate with the bromine test (which is capable of
detecting in a solution the 1/60000 part of phenol). The aqueous
extract is at this point evaporated, then ether is added, and finally
the ethereal solution is allowed to evaporate. The residue (phenol) is
weighed directly, and from this the percentage can be ascertained. By
this method of extraction, the oil of turpentine, resins, etc.,
contained in _Pinus sylvestris_ do not pass into solution, because
they are insoluble in water, even when boiling; what passes into
solution besides phenol is a little tannin, which is practically
insoluble in ether.
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