342 C. Barus — Effect of Temperature and of Moisture 



for some reason weak as a nuclei producer. I, therefore, 

 washed and scoured the surface of the grid, obtaining the 

 usual order of values in the second part of the table. On the 

 other hand, the currents in the first part are larger than those 

 of the second part. Here again, therefore, the tendency to 

 produce nuclei reciprocates in intensity with the tendency to 

 produce ions, or better to produce conduction in the condenser. 

 The latter is facilitated by the presence of traces of moisture, 

 but nuclei are not so produced. 



19. Corroborative experiments with damp paper. — Another 

 method of throwing light on the inquiry will be a comparison 

 of the conduction produced in the condenser by air passing 

 over damp filter paper with the corresponding case of air pass- 

 ing over phosphorus. 



The wet paper (omitting the data) behaves in a less intense 

 way something like the phosphorus. The rise of conduction, 

 however, is gradual, the conduction at best moderate and the 

 return of the condenser to the original degree of insulation 

 relatively rapid. With phosphorus, the conduction after the 

 first minute or so has risen to the immeasurably large values 

 and when the air current ceases the condenser shows similar 

 conduction. Much more dry air is needed to dry the con- 

 denser and the phosphorus to normal values (fully twice as 

 much as in the preceding case). Eventually the currents also 

 return to the normal, relatively small limit and the insulation 

 of the condenser is nearly perfect again. 



Qualitatively the two phenomena run in parallel ; quantita- 

 tively, they are enormously different. Inasmuch as the paper 

 is obviously wet, whereas the phosphorus grid has been dried 

 short of desiccation, inasmuch as any emanation must behave 

 like a water evaporation, I think that the volatile body 

 is probably of the nature of a hydrophosphide. Some electri- 

 cally active substance is distilled in the presence of moisture 

 and precipitated in the condenser. 



20. Corroborative experiments with desiccators. — The final 

 test made to detect the character of the emanation was one of 

 direct desiccation over chloride of calcium, before insertion. 

 The day happened to be damp and the insulation poor. The 

 experiments, however, are none the less definite. 



(1) Phosphorus dried in air and inserted into the dried tube 

 of the water bath, ab, figure 1 ; the condenser was at once dis- 

 charged on passing the air current through it. On removing 

 the phosphorus the condenser showed too large a leakage to 

 admit of the measurement of current. All appurtenances were 

 now dried in a current of dry air and the final insulation deter- 

 mined. 



(2) The phosphorus grid having been placed for about 15 



