C. in closed
vessels for two hours, with a very weak solution of sodium hydrate and
petroleum (boiling between 200 deg. and 250 deg. C). The mass is filtered,
pressed while still tepid, and the filtrate allowed to stand until the
oil has completely separated from the aqueous solution. The oil is
drawn off and carefully neutralized with very weak hydrochloric acid.
A white bulky precipitate of cocaine hydrochloride is obtained,
together with an aqueous solution of the same compound, while the
petroleum is free from the alkaloid and may be used for the extraction
of a fresh batch of leaves. The precipitate is dried, and by
concentrating the aqueous solution a further quantity of the
hydrochloride is obtained. Both can be shipped without risk of
decomposition. The product is not quite pure, but contains some
hygrine, traces of gum and other matters. Its percentage of alkaloid
is 75 per cent., while chemically pure cocaine hydrochloride
(C_{17}H_{21}NO_{4}.2HCl) contains 80.6 per cent. of the alkaloid. The
sodium hydrate solution cannot be replaced by milk of lime, nor can
any other acid be used for neutralization. Alcohol or ether are not
suitable for extraction. A repetition of the process with
once-extracted coca leaves gave no further quantity of cocaine,
proving that all the cocaine goes into solution by one treatment.
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