1906.] 



The Pharmacology of Ethyl Chloride. 



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of increase was maintained for 7' 30", and it was 17' 30" after the dis- 

 continuance of the ethyl chloride ere it began to diminish. 



These experiments demonstrate that the effect of ethyl chloride upon the 

 arterioles isolated from the central nervous system is relaxation. In this 

 respect it is similar to chloroform, but the amount required is vastly greater. 



(2) The Effects of Ethyl Chloride upon the Central Vaso-motor System. 



This was investigated by conveying the ethyl chloride to the brain alone, 

 upon the lines pursued by Gaskell and Shore (7) in their work on chloroform. 

 They employed an extensive proceeding, which consisted in connecting the 

 vessels to and from the brain of one dog with the circulatory system of 

 another and larger dog, so that the larger dog supplied the brain of the 

 other dog. The chloroform was then administered to the larger dog and 

 records taken of each. The brain alone of the smaller dog received 

 chloroform. In the following experiments an artificial arterial circulation 

 replaced that of the large dog of Gaskell and Shore's experiments. 



The defibrinated blood of another dog, containing various known 

 percentages of ethyl chloride, was delivered by the artificial arterial 

 circulation apparatus to the brain through the two carotid arteries, for 

 short periods at a time. The temperature of the blood in this artificial 

 supply was 38° C, and the pressure the same as that in the femoral artery 



