Ionized Phosphorus Emanation in Tubes. 



45 



(conducting and insulating) which makes up the absorbing- 

 walls, the proximity of the values of k is particularly 

 noteworthy. No relation to diameter is apparent. In case 

 of glass, of impure grey rubber, of pure brown rubber, and 

 of lead, this velocity k, so far as observation warrants, is the 

 same. 



4. In contrast with these results with tubes of relatively 

 small bore, I shall now add data for wide tubes. They were 

 5 centims. in diameter (2-inch drain -pipe of tin plate), and 

 they may be regarded as direct prolongations of the influx- 

 pipe 0' of the colour-tube. The air passing through these 

 tubes is moved by the suction of the steam-jet, and is inde- 

 pendent of the ionizing current through the gasometer. The 

 velocity of the air-current through the tubes (often 50 feet 

 long) was about 100 centims. per second, and was determined 

 by the time it takes the " dust/' suddenly injected into one 

 end of the tube, to show itself at the other end by colouring 

 the steam-jet. The phosphorus emanation (V litres per 

 minute) was introduced into the current at distances 150 and 

 1500 centims., respectively, from the jet, as the data show. 

 The table gives but a single series among many. The velocity 

 is here computed from 



k=(rv/2(x-./))\og (V/V), 



where the volumes V and V correspond to the tube-lengths 

 x and x' . 



Table III. — Absorption of Phosphorus Emanation in Tin 

 drain-pipe. Diameter, 2r = 5 cm., p = 4 cm., = 28°. 



Field of the 

 Colour-tube. 



Length, 

 .r. 



Volume 



per min., 



V. 



Velocity, 

 v. 



k. 





cm. 

 150 



150 



150 



1500 



1500 



1500 



litr. min. 

 •70 



1-10 



1 05 



115 



2-00 

 200 



cm. /sec. 

 (100) 



(100) 



cm. /sec. 

 •05 



■06 



•06 



Blue 



Dark blue 



Blue-green 



Blue 



Dark blue 





These results have also been constructed in the chart on 

 the same scale as the other curves, the data selected being 

 those showing the maximum effect of length. In fact, these 

 results are liable to be very variable, as the colours for the 



