272 BASKERVILLE— RATE OF EVAPORATION. [April 23, 



matically regulate any anesthesia that might be induced in this 

 manner. As a result, Gwathmey presented a paper before the seven- 

 teenth International Medical Congress in London in 191 3 on the 

 work with animals done by himself and Wallace. 



At the request of my co-laborer, Gwathmey, I undertook an in- 

 vestigation on the rate of evaporation of ether from oils to secure 

 the following information that might be of service to him in his 

 further application of his ideas with human subjects: 



1. A comparison of the rate of evaporation of ether from dif- 

 ferent mixtures of ether and the same oil. 



2. A comparison of the rate of evaporation of ether from the 

 same per cent, mixtures of different oils and ether. 



3. The influence of surface on the rate of evaporation was de- 

 termined. 



As the result of much preliminary experimentation, the follow- 

 ing mode of procedure was settled upon. Large glass tubes were 

 calibrated to i c.c. from 20 c.c. to 105 c.c. The mixtures of 25, 50 

 and 75 per cent, of oil and ether were carefully placed in the tubes. 

 The tubes were weighted with lead and placed in a thermostat, 

 whose temperature was so regulated as not to vary more than 

 ih 0.03° C. from 37° C, the same being controlled by a toluene -\- 

 mercury temperature regulator. All connections (gas, water, etc.) 

 were made with lead pipe for safe use over night, as occasion arose. 

 The water in the bath was stirred by a system of paddles and shaft 

 operated through belt and pulleys by a small hot air engine. The 

 tubes were immersed in the bath to within 2 cm. of the tops. Dur- 

 ing the first five minutes two readings were made in each case to 

 get the highest point to which the volumes expanded upon heating 

 up to 37° C. After that readings were made every five minutes 

 for two or three hours. 



Since the evaporation of any liquid depends upon the partial pres- 

 sure of that liquid at its surface, the higher the glass wall above the 

 surface of the oil-ether mixture, the heavier the column of ether 

 vapor resting on the surface of the mixture, the slower will be the 

 evaporation, consequently the different oil mixtures with the dif- 

 ferent percentages of ether were experimented with in the same tube 

 filled to the same height in each experiment. 



