Page 363 - My FlipBook

COCAINE.
361
Cocaine is also employed in combination with arsenious acid
for a pulp-devitalizing mixture. (See Arsenious Jcid.) One
grain of cocaine to one-eighth ounce of chloroform is employed
for extirpating pulps without pain.
Cocaine Incompatibles.—When combined with nitrate of silver,
decomposition of the hydrochlorate occurs with the formation of
an insoluble chloride of silver, and a corresponding change in the
cocaine. If calomel and hydrochlorate of cocaine are rubbed
together, chemical reaction begins. Added to mercuric oxide,
an irritating instead of an anaesthetic action is produced, due to
the formation of oxychloride of mercury.
Test for Presence of Cocaine.—H. Carlton Smith gives the fol-
lowing simple test : " To a solution of cocaine was added a few
drops of ferric chloride ; the iron was reduced as usual ; then the
addition of a single drop of stannous chloride produced a white
precipitate. This disappeared upon shaking, but one or two
more drops of the chloride of tin reproduced it, and this time it
was permanent."
Vapocaine consists of a fifteen per cent, solution of cocaine
hydrochlorate in ethyl ether, and is employed as a dentinal anaes-
thetic. It is neutral to litmus paper and is the production of an
ethereal solution of a cocaine salt. It is principally used as an
obtundent for sensitive dentine, and it is claimed for it that as
aqueous solutions of cocaine salts fail to penetrate the dentine,
and the ethereal solution of cocaine alkaloid is deficient in anaes-
thetic property, an ethereal solution of a cocaine salt, besides pos-
sessing anaesthetic properties, will secure the maximum of anaes-
thesia with the use of a minimum amount of cocaine. Vapocaine
possesses great penetrating power, which is due to the fact that
the heat of the mouth vaporizes a portion of the ether, and drives
the natural fluid of the tooth out of the tubuli, thus securing a
rapid distribution of the remaining portion throughout the tooth
structure. From this portion the ether is dissipated, leaving the
cocaine salt distributed in minute subdivisions throughout the
tubuli. The cocaine is then redissolved by the natural fluid of
the tooth, securing a rapid and effective anaesthetic. By its use
the natural moisture of the tooth is made to act as a solvent for