on the Emanation of Phosphorus. 343 



minutes in the desiccator was again inserted into the tube, ao. 

 The current now obtained was ds/dt = 37 ; the insulation 

 proved to be ds/dt — 30. Hence the current due to ionized 

 air was but ds/dt — 7, an abnormally small value, indicating 

 the absence of moisture. 



The phosphorus grid was once more put in the desiccator 

 for 15 minutes. After replacing it in the water bath the cur- 

 rent observed was 40 ; the insulation 27. Hence the leakage 

 due to ionized air is here ds/dt = 13, agreeing with the usual 

 order of ionized values above. 



Owing to the unfavorable condition of these experiments, 

 not much definiteness was to be anticipated from them ; but 

 they show clearly that the enormous initial emanation from 

 fresh phosphorus is all but wiped out, relatively speaking, 

 after the phosphorus has been dried preliminarily over calcic 

 chloride. Whether in the rigorous absence of all moisture 

 phosphorus would cease to ionize air, remains to be seen. It 

 is also a question whether the desiccation over calcic chloride 

 may not be accompanied by detrimental chemical action, refer- 

 able to the chloride. At least the following work continues 

 to show that the phosphorus grid repeatedly treated in this way 

 continually loses strength as an ionizer, in spite of the inter- 

 mediate submersion in water to keep it over night. 



21. Effect of prolonged drying. — A final attempt was made 

 to see if after continued drying over calcic chloride the ioniza- 

 tion would be wiped out altogether. The following table 

 shows this to have been unsuccessful. The room was favor- 

 ably dry and warm and the leakage errors in the condenser not 

 appreciable. After nearly 5 hours the potency of the ionizer 

 is not diminished (see figure 11). It has rather increased, due 

 possibly to the attraction of traces of moisture even within the 

 permanently dried tube of the apparatus, figure 1. An extra 

 tube of calcic chloride was attached. In a second experiment 

 the temperature effect is tested for this specially dried phos- 

 phorus. The corresponding graph is shown in figure 10, and 

 the ionization is weaker than in any earlier experiment. 

 Nevertheless the results show maximum activity in the neigh- 

 borhood of 20°, though even at 12° the ionization is not 

 quite extinguished. The exceptionally low ionization is not 

 accounted for except as due to deficient phosphorus, the natu- 

 ral result of long continued consumption. 



22. Promiscuous experiments. — Having investigated the 

 effect of the temperature of the body of phosphorus on its 

 emanation, I next purposed to ascertain the dependence of the 

 emanation itself on temperature. This could be done by sur- 

 rounding the condenser by a steam jacket (shown in figure 2, 

 jj y s, s, being the influx and efflux pipes) and noting the effect 



Am. Jour. Sci.— Fourth Series, Yol. XII, No. 71.— November, 1901. 

 24 



