EXPERIMENTS ON PRESSURE OF LIGHT 49 



fitting in the neck. It is not necessary to describe 

 here in detail how the flask was exhausted. It 

 is sufficient to say that it was filled with dry 

 oxygen and exhausted many times, and that 

 finally it was sealed off at S, fig. 19, when ex- 

 hausted, and that the bulb C, containing charcoal, 



FIG. 19. 



was surrounded by liquid air kept boiling at low 

 pressure for some hours before and during an ex- 

 periment. The residual oxygen was then nearly 

 all absorbed by the charcoal, and the vacuum, as 

 the behaviour of the apparatus showed when light 

 was directed on to the discs, was exceedingly 

 high. 



