44 



Prof. C. Barus on the Absorption of the 



from the theory presently to be given. For the wider tubes 

 and greater lengths the higher volumes sometimes show a 

 break in the curve (cf. lead), meaning, I think, that the 

 phosphorus ionizer is being overtaxed by the quantity of 

 ■charged air demanded. 



Chart showing the litres per minute of air saturated with phosphorus 

 emanation, needed to produce a full blue field in the colour-tube for 

 different lengths of absorption-tube. 



In view of the difficulty * of observing, subject to colour 

 criteria, the widely different values of the velocity with which 

 the ionized air traversed the absorption-tubes, the high 

 velocities employed, and the marked difference of material 



* Add to this the variable ionizing intensity of phosphorus, the most 

 baffling of discrepancies. 



