LOCAL ANASTHESIA. 45 
pian and Panas made it popular in France. Reclus published some 
excellent papers on its application. Labat proved that it could be 
used with benefit for animals. \ 
Cocaine is almost insoluble in water, but most of its salts in any 
proportion are readily dissolved by it. The most generally used is 
the muriate of cocaine in solution of 1 per 100. The addition of 
a small quantity of corrosive sublimate insures the purity of the 
solution for preservation. We use the formula recommended by 
Reclus. 
Muriate of cocaine .......... 
Sublimate........ 
Distilled water 
...10 Centigrams 
+» 2 milligrammes 
cia’ sis ietbig.ayeldi grains sis ale aiwig aie Oe Vareisiniwiaate Se aperes satan 10 grammes 
With a few drops of this collyrium dropped between the eyelids 
the superficial layers of the cornea are rendered insensible in three 
minutes. ; = 
By repeating this process at intervals of two minutes anesthesia 
of the cornea, of the conjunctiva, and of the eyelids is complete in 
less than ten minutes, and lasts for fifteen. The pupil dilates ; but, 
generally, the anesthesia of the iris is only obtained by an injection 
made into the anterior chamber. With cocaine, puncture of the 
cornea and the extraction of foreign bodies incrusted in it are made 
easily. Five or six injections under the conjunctiva, round the ball 
of the eye, will permit its entire removal without great pain. 
The action of cocaine is not less remarkable upon other mem- 
branes. On that account its use is prescribed for painful inflamma- 
tion of these structures. Subcutaneous and submucous injections 
of cocaine will remove sensibility from superficial tissues, and per- 
mit various operations to be performed. By injections in linear or 
circular tracts the area of the influence of the anesthetic can be 
increased. A long and fine canula, fitted to a Pravaz syringe, is. 
introduced through the skin into the subcutaneous cellular tissue, or, 
better, into the thick dermis, following the direction of the incision to- 
be made. Then it is withdrawn gradually while ‘the piston of the 
syringe is pushed in. In this way the solution is diffused in a linear 
track. (Reclus.) The anesthetic power of cocaine is increased by 
a previous injection of morphine. 
Cocaine has no action upon nervous cells. It acts exclusively 
upon the terminal fibres of the sensitive branches. (Arloing. ) 
Its toxicity varies according to the kind of animal. For dogs, 
more than 5 to rocentigrammes are dangerous. Concentrated solu- 
tions have no advantages and are dangerous. In every degree of 
‘concentration, solutions of cocaine, when they become acid, lose, 
‘more or less completely, their anzsthetic properties, which can be: 
restored if the liquid is rendered neutral. 
