THE ADMINISTRATION OF ANAESTHETICS 



25 



rubber bellows, and falling directly in the form of a very fine 

 spray on the required spot. 



Ethyl chloride and anestile, which are also applied in the 

 form of a spray, are sold in a very portable and neat form in 

 small glass or metal vessels (see Fig. 18). 



They are apphed directly to the spot at which anaesthesia 

 is to be produced by merely removing the metal cap from the 

 end and holding the bottle in the warm hand. 



These three agents are also best suited for minor opera- 

 tions, such as the lancing of abscesses, the anaesthetizing of 

 the skin, or the removal of small superficial tumours, and 

 are not readily applied to thick muscular tissues where a 



Fig. i8. — Glass Tube containing Ethyl Chloride ready for Application. 



considerable amount of dissection has to be done ; the 

 reasons being that, if a thin layer only be frozen, the warm 

 blood (when the incision is made) prevents the further 

 application of the ansesthetic, whilst if the whole mass be 

 frozen first it is difficult to cut, and there is the danger of 

 necrosis as a sequel. 



As a general rule, anaesthesia is produced when the skin 

 has turned white ; this occurs in from half a minute to a 

 minute and a half, and the effect lasts for about two minutes.^ 

 Care must be taken not to keep the parts frozen for too long 

 a time, or necrosis may follow. 



' Journal of Compaj-ative Patliology and Therapeutics, vol. ix., p. 227. 



