hloric acid, the product filtered, and excess of sodium hydrate
added thereto, quinine and quinidine are precipitated: on
concentrating the mother liquor, cinchonine falls down, and on further
concentration with addition of still more alkali, cinchonidine is
thrown out. Yellow bark, which is not official, yields 3% of quinine,
and pale bark about 10% of total alkaloids, of which hardly any is
quinine, cinchonine and quinidine being its chief constituents. The
various forms of bark also yield a very small quantity of an
unimportant alkaloid, _conquinamine_. In addition to the above, red
bark contains _quinic acid_, C7H12O6, which is closely allied to
benzoic acid and is excreted in the urine as hippuric acid. There also
occurs _chinovic acid_, derived from a glucoside _chinovin_, which
occurs as such in the bark. Besides a trace of volatile oil which
gives the bark its characteristic odour, and cinchona red (the bark
pigment), there occurs about 2% of _cincho-tannic acid_, closely
allied to tannic acid and giving the bark its astringent property.
Cinchona is never used, however, in order to obtain an astringent
action.

The importance of recognizing the complex and inconstant composition
of cinchona bark lies, as in so many other instances, in this--that
the physician who employs it can have only a very imperfect knowledge
of the drug he is using. The latest work on the action of these
alkaloids has shown that cinchonine has a tendency to produce
convulsions in certain patients, and that this action is a still more
marked feature of cinchonidine and cinchonamine. Even small doses
administered to epileptics increase the number of their attacks. They
will probably be classified later among the convulsive poisons. The
use of cinchona bark and its preparations, now that definite active
principles can be readily obtained and precisely studied, is almost
entirely to be deprecated. Quinidine is almost as powerful an antidote
to malaria as quinine; cinchonidine has about two-thirds the power of
quinine, and cinchonine less than one-half.

CINCINNATI, a city and the county-seat of Hamilton county, Ohio, U.S.A.,
on the Ohio river, opposite the mouth of the Licking, about 100 m. S.W.
of Columbus, about 305 m. by rail S.E. of Chicago, and about 760 m. (by
rail) W.S.W. of New York. Through the city flows Mill Creek, which
empties into the Ohio. Pop. (1890[1]) 296,90