1920] 



on Low Temperature Studies 



261 



the limit was reached under the same circumstances in about 

 1 J minute, and with helium (same figure), which of course is scarcely 

 condensed at all at this temperature, the response was almost all 

 registered in § minute. These two results show incidentally that 

 the temperature lag of the bath must be very small. For comparison 

 here, also, the corresponding normal thermoscope responses to the 

 Leslie cube are shown in separate curves. 



All these results were the same, whether made on the membrane 

 cell or on the silver chloride cell, so that no distortion of the 



PRESSURE m 

 CMS of ALCOHOL 



IOO°RAD 



MINUTES 



PRES5URE in 

 CMS of ALCOHOL 



O j> 4 6 MINUTES 



Fig. 10. — Charcoal Saturated with (1) Hydrogen, (2) Helium. 



membrane under small differences of pressure will explain them. On 

 the other hand, if no charcoal is present in the cell some effect can 

 be detected from this cause, but the response is in all cases regis- 

 tered instantaneously. The curves in Fig. 11 give this response for 

 different increments up to 20 cm. This pressure was calculated to 

 correspond to a load of 180 grammes weight on the membrane. The 

 response of the manometer, on the other hand, due to the stretching 

 of the membrane, corresponded to a load of only 72 grammes, or a 

 pressure of 8 cm., and so on for lower values. In this figure is 

 also included the response obtained by an ordinary exposure, which 



