THE STltldTt'RE OK THE NUCLEUS. 



other, the tbennul variation of k is insignificant coiiniared witii tlie correspuiidiiig 

 decrease of N. 



7. JJatu for low ieinperatures. — After finisliiiig the electrical investigation 

 presently to he discussed, it seemed desirable to corroborate the al)ove results with 

 new obseivations made near tiie temperature at which phosphorns becomes active. 

 These are briefly given in table 2. As a whole, they agree with the above infer- 

 ences. It was discovered, however, that permanent though faint colors could be 

 obtained even below the limits stated al)r)ve (13), by veiy gradually increasing tlie 

 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, ll is thus possible to ''blow out" the emanating activity of the jjhosphorus 

 with a current oidy a trifle fastei' than the one which produces the corres|><>niling 

 color ma.vimum. The puffs of color obtained above are the same phenonnMion. 

 Heiow 13", opaque did not occur. At 14° the full activity was accentuated. 



ki,K(ti:k' \r. comi'akisons. 



8. Api>(irattiH. — It is now desiraiile to com[)are these data with the results 

 obtainal)le in measuring the radial currents in the tubular condenser which is made 

 the channel of communication between the pipe, (il>, of the water bath, figure 1, and 

 the color tul)e, ('. In otlici' words, the tuiiulure, (r, is now replaced by the con- 

 denser, A'A', figure 2, for discharging ionized air into O, by fitting the tubulure h 

 to the end a of the ionizer, figure 1. Details of adjustment are given in my 

 earlier volume. The slender condenser, K I\, was effectively 50 centims. long, .32 

 centini. in internal, and .00 ceutim. in external diameter. The inner face (surface 

 of the rod, ciJ) is charged to about 40 volLs. The tul)e KK, insulated at the ends 

 from the rod, is })ut to earth at E. The electrical discharge takes place radially 

 from rod to tul)e, ami should occur only when the emanation passes in the cylin- 

 drical shell between the faces (.14 centim. thick and 50 centims. long), entering at 

 h and leaving at (t. It is difficult in so slendir an .ipitaratus and in view of the use 

 made of it to avoid conduction through the insulators, altogether, [larticularly in a 

 d:unp atmosphere. Hence in the following tables the insulation, when the medium 

 is orilin;iry air, is given ; l)ut even if ignored it will not probably affect the relation 

 t(» temperature. In a warm steam-heated room the insulation is perfect, and 

 advantage was frcipicntly taken of this convenience. 



A steam or water jacket, J, surrounds the condenser for special e.x'periments. 

 jj 22. Steam enters and leaves by the tubnlures, .v. 



1*. Mitliod. — The method consisted in leading the efllu.x volumes, V, at the 

 gasometer or as|iirator bottle, before and after the series of electrical measurements. 

 As the latter were always duplicated, three volume measurements were made at 

 stated times. From these dV/dt was (tbtained graphicallv. 



'i'lie fall of potenti.'d at the electrometer (cajiacity of the latter 360 centims., in 

 parallel with th.ut of the condenser, 39 centims.) was observed at intervals of 15 

 seconds apart. Eight readings in two series were made between the volume read- 



