1906.] 



The Pharmacology of Ethyl Chloride. 



393 



The determinations were made in a special absorptiometer, which was kept 

 at constant temperature by means of a water-bath, and in which arrangements 

 were made for continuous shaking of the bulb containing the water or blood 

 respectively. The bulb communicated by means of a narrow-bored tube with 

 a gas burette containing the vapour of ethyl chloride. Measured quantities 

 of vapour were passed into the bulb from time to time as absorption progressed, 

 and the actual quantity taken up determined. The pressure in the absorp- 

 tiometer was maintained constant by a variable mercury level. 



In these determinations the blood was found to lake in the earlier part of 

 the absorption process, but no massive formation of haemoglobin crystals 

 occurred as in the case of chloroform under like conditions. Blood absorbs 

 more than twice as much of the gas as water under similar conditions. Ethyl 

 chloride, like chloroform, evidently enters into chemical union with the 

 blood. 



Effect of Ethyl Chloride upon the Heart Isolated from the 

 Central Nervous System. 



In a previous investigation (5) of the effect of chloroform upon the isolated 

 heart the method of Hering was employed. As, however, some difficulty is 

 apt to happen in this method in consequence of the tendency to the 

 formation of clots in the U -cannula when the blood-pressure falls, I have 

 devised the following method, by means of which a circuit is maintained 

 without the introduction of foreign bodies, such as cannula?, for establishing 

 continuity. 



It consists in the ligation of all of the arterial trunks except the left 

 subclavian, the aorta being tied just beyond the left subclavian artery. 

 The ascending branches of the left subclavian and the vertebral arteries are 

 then tied. One of the carotid arteries was used for recording the blood- 

 pressure. The vagi were divided. The blood supply to the central nervous 

 system was thus cut out and the operation of the central nervous system 

 was in this way abolished. The heart circulated normal arterial blood. 



In experiments under the above conditions, in which simultaneous 

 blood-pressure curves and plethysmographic records of the changes in the 

 volume of the left leg were taken under chloroform narcosis, it was found 

 that the changes in the blood-pressure were accompanied by corresponding 

 changes in the volume of the foreleg (left) in which the circulation was affected. 



Definite mixtures of ethyl chloride and air were administered by artificial 

 respiration from a gasometer in which the mixture was contained. The 

 Cambridge Scientific Instrument Company's apparatus was used for artificial 

 respiration. 



2 H 2 



