THE STRUOTORK OF TnK NUCLEUS. 



21 



24. Older data compared tvith the present data. — It is finally worth while to 

 adduce the corresponding data of an eai'lier paper. The equivalent colors of the 

 steam tube are the yellows and ci'iiiisons of the second order. The temperatures 

 are 20°-30°. 



TABLE 12.— RELEVANT DATA FROM EARLIER PAPERS. yt'„ = 40 VOLTS. 



10- X 



dl'ldt 



10= X 



Clearly then, for dV/dt = .43, nearly, the order of values for the cuirents is 

 the same hei'e (the experiments made over a year ago, but with the same grids) as 

 in the above experiments. The room being very hot iusui'ed dryness in that woi'k 

 without preliminary desiccation. Large volumes of dry air had been passed over 

 the grids, moreover ; For colors of the first order were principally observed, requiring 

 even as much as 3 liters/min. [)er observation. 



The arrows (n, new and 0, old) in figure 9 show the relation of the results in 

 the last table to the values for freshly cut phosphorus in excess given at the begin- 

 ning of paragraph 23. Since from the old vahies the number of nuclei was 

 computed as ?i = 8 X 10*, the new values would make them approach w = 16 X 10*, 

 about half the datum found with plate and with spherical condeuseis by entirely 

 different methods, rememberins- that from the occurience of an absorbiuii influx 

 pipe, the air within the tuljular condenser can nowhere be quite saturated. 



25. Condimon and suminar(/. — The experiments with j)hosphoi-us show that 

 nuclei adapted to condense atmospheric moisture are produced most abundantly 

 at about 13° C. Below this, the I'ate of production deci-eases with enoi-mous 

 ra[)idity (just shoi't of suddenness), probably ceasing at about 8". This holds 

 true for very different velocities of the dry air passing over the phosphorus. 

 Above the reaction temperature, the activity decreases slowly as temperature 

 rises, having not deci'eased more than 25 per cent at 35°. Since the phosphorus 

 is superficially heated by the reaction, sharp statements are out of the question. 



Below 13°, the opaques of the color series are absent and the maximum 

 tints are fainter and of increasingly higher oi-ders. The strongest permanent 

 color may be reached by very gradually increasing the charged air current. A 

 limiting velocity decreasing with temperature may thus be reached, beyond 

 which all colors vanish and the reaction is qiiite " blown out," as it were. It 

 is probable that in these experiments the chemical I'eaction supplies the defi- 

 ciency of temperature. Suddenly opening the stop-cock after a period of qui- 

 escence shows puffs of color under these conditions, which also vanish as 

 temperature decreases below 13°. Putting JV=hi, where JV is the number of 



