on the Emanation of Phosphorus. 



331 



to corroborate the above results with experiments made near 

 the temperature at which phosphorus becomes active. Asa 

 whole the new data agreed with the above inferences. It was 

 discovered, however, that permanent though faint colors could 

 be obtained even below the limits stated above (13°), by very 

 gradually increasing the speed of the charged air current from 

 zero until the field showed, the limiting coloration for the 

 low temperature selected. When the air current is further 

 increased, however slightly, the field of the color tube at once 

 clears, almost with a flash. It is thus possible to "blow out " 

 the emanating activity of the phosphorus with a current only 

 a trifle faster than the one which produces the corresponding 



a 



^^^^ 



jRg2. 



J 



color maximum. The puffs of color obtained above are the 

 same phenomenon. Below 13°, opaque did not occur. At 

 14° the full activity was accentuated. 



Electrical Comparisons. 

 8. Apparatus. — It is now desirable to compare these data 

 with the results obtainable in measuring the radial currents 

 when the tubular condenser is made the channel of communi- 

 cation between the pipe, ab, of the water bath, figure 1, and 

 the color tube, C. In other words, the tubulure, G, is now 

 replaced by the condenser, KIT, figure 2, for discharging 

 ionized air into O, by fitting the tubulure b to the end a of the 

 ionizer, figure 1. Details of adjustment are given in my 



