1921] 



on Cloudland Studies 



439 



equilibration pressures so obtained did not exceed 0*005 mm. The 

 experiments were made in a dark room, and the charcoal bulb was 

 cooled in a glass vacuum vessel enclosed in a black screen. A slit 

 and shutter allowed the light from a 45-watt tungsten lamp to be 



AIR 



PRESSURE 

 •006 



•OCH- 



•002 



10 15 20 



NITROGEN 



25 MINUTES 



PRESSURE 

 •008 



•006 



10 15 20 



HYDROGEN 



25 MINUTES 



•00V 



002- 



0-06CC. 



O 5 10 15 2C 25 MINUTES 



Fig. 22. 



focussed on the charcoal bulb from a distance of 1 metre. Increases 

 of pressure were observed in all cases, reaching their maximum in 

 about five minutes with air and nitrogen, and disappearing in about 

 the same time when the shutter was closed. The volumes admitted 



