60 cocAiNii. 



nervous trunks supplying the part are very imperfect methods. For 

 a long time ice refrigerating mixtures and ether spray were exclusively 

 used. Cocaine was afterwards discovered, and soon became popular. 

 Eucaine, novocaine, and stovaine are also used ; and when the 

 operation is likely to be accompanied by moderate bleeding, solution 

 of adrenalin is added to the anaesthetic before injection. 



Anaesthesia by Cold. The prolonged action of cold renders super- 

 ficial tissues bloodless and diminishes or even abolishes sensibility. 

 Refrigerant mixtures have been used in operations like neurectomy. 

 Crushed ice and salt, mixed in the proportion of 2 to 1. are packed 

 into a long bag and applied to the region of operation. In a few 

 minutes, especially if the bag is pressed firmly into contact with 

 the part, the skin becomes cold, firm, and insensitive, and incisions 

 unless deep neither provoke pain or haemorrhage. The anaesthesia, 

 however, is of short duration, and operation must be rapid. 



By projecting an ether spray on the parts the temperature is 

 soon so far reduced that trifling operations may be performed without 

 pain. The action is rendered more rapid and complete by previously 

 applying an Esmarch bandage. It is difficult, however, to render 

 inflamed parts insensitive, and for this purpose the usual refrigerating 

 mixtures are preferable. 



Methyl bichloride, successfully used in man for troublesome 

 neuralgia, is almost too active, and though rendering the skin 

 insensitive in a few seconds not infrequently freezes it, causing more 

 or less extensive necrosis. 



Local Anaesthesia by Cocaine. Cocaine is almost insoluble in 

 water, but the greater number of its salts dissolve freely. The most 

 frequently employed is hydrochloride of cocaine of 1 to 10 per cent, 

 strength. The addition of a trifling amount of bichloride of mercury 

 insures the solution keeping. Reclus recommends the following 

 formula : 



Hydrochloride of cocaine . . 1| grains. 



Sublimate . . . . . "03 grain. 



Distilled water . . . . 2 J fluid drachms. 



A few drops of this solution placed between the eyelids render the 

 superficial layers of the cornea insensitive in three minutes. 



By repeating the application at two-minute intervals the cornea, 

 the conjunctiva, and eyelids are often completely insensitive in less • 

 than ten minutes, and anaesthesia lasts a quarter of an hour. The 

 pupil dilates, but as a rule the iris is not rendered insensitive unless 

 the injection is made into the anterior chamber. By this method 

 puncture of the cornea and removal of foreign bodies fixed in the 



