64 



EXPERIMENTAL PHARMACOLOGY 



is used to connect the pin hook in the tendo Acliillis to the 

 muscle lever. The secondary terminals can then be at- 

 tached to the muscle lever and to the muscle clamp. 



Ethyl Ohloride. (Local Anesthesia.) 



5. Hold a Gebauer or Kelene tube about 10 or 12 inches 

 from the hand and open the valve a little. A small spray 

 of the drug will be forced out. Why? Direct this spray 



-Time 

 circuit 



Receptacle for lnd c + ori m ^P^ key 



electrodes when no+ in use. 



The wire of the electrodes should be 6 



ft lona ana made of very small sized 



/smp-cord 



Fig. 59. Convenient method of arranging the inductorium, battery, key and elec- 

 trodes to avoid tearing down the apparatus at each period. The inductorium is out of 

 the way and always ready for use. 



against the back of the hand. A white frost will soon ap- 

 pear on the skin and hairs. A few seconds after this frost 

 begins to form stop the spray and quickly examine the sen- 

 sibility of the skin in the area affected. To what is this 

 action due? To what clinical use might this be applied? 

 Can you think of other substances having a similar ac- 

 tion? Is this action of ethyl chloride in any way similar 

 to that of ether, ethyl chloride, or chloroform, on the irrita- 

 bility or conductivity of nerve trunks? What is the boiling- 

 point of ethyl chloride ? If a local anesthetic be applied to a 

 mixed nerve trunk will all the constituent fibers be equally 

 affected at the same time? 



