

CHAPTER IV. 



THE TRANSMISSION OF THE IONIZED EXHALATIONS OF PHOSPHORUS THROTJOH AIR AND 

 OTHER MEDIA, IN THE PRESENCE OF AN ELECTRIC FIELD. 



TRANSMISSION THROUGH AIR. 



1. Object and plan. — The experiments of the present chapter' are made with 

 an electrical method. They relate to the upparant decay of the ionization produced 

 l>y phosphorus, in the lapse of time, for fixed distances apart of the condenser plates; 

 to the transmission of the ionization through layers of air and other media and bar- 

 riers. They are thus preliminary to the subsequent experiments, in which the con- 

 denser and the color tul)e are combined and the coincident effects interpreted. I 

 hope moreover to decide whether a form of radiation from phosphorus is pi-esumable 

 or whether the case is merely that of an ionized gas exhaled by the slowly oxidizing 

 body. I shall venture to treat the results in a simple and direct manner, in older 

 to present them more consistently wath my earlier chapter on the same suV)ject, in 

 which the attempt was made to arrive at the ion velocity of the phosphorus emana- 

 tion by anon-electrical method and therefore in the absence of an electrical field. 

 Finally I want in particular to ascei'tain whether by giving less piominence to the 

 decay of ions by mutual destruction within the element of volume, or otherwise, the 

 phenomena may not be equally well explained. 



2. Apparatus and method. — To turn first to the behavior of phosjihorus in 

 contributing in the lapse of time to the discharge of a simple air condenser whose 

 plates are at fixed distances apart, the following experiments were made; In 

 figure 1, 2)., is a water l)attery of 48 volts, permanently charging the quadivints of 

 an Elliott electrometer, one of w^jich is always earthed and controlled by the 

 switch, S^. Bj is a storage battery (20 cells suffice) one pole of which is kept 

 earthed as determined by the switch aS'j, to be closed momentarily on charging. 

 The other terminal charges the two condensers in parallel, 3f, JV, in the electro- 

 meter and C, 1\ for the ionization experiment. The plates M and P are also pei- 

 manently earthed. ^Vconununicates in the usual manner with the needle of the 



' Scienct, XI, p. 201, 1900; XIII, p. 501, 1901; Physical Rnnav, X, p. 257, 1900; and the cur- 

 rent numbers of the Phil. Ma^. The ionization of the phosphorus emanation was known to 

 Matteuci and has been studied since by Neccari. It was rediscovered by Bidwell {Nature, Dec, 

 p. 212, 1893). Cf. Nature, LV, pp. 6, 125, 155, 1897; also XLIX, p. 363, 1894. I believe I was 

 the first lo point out its remarkable activity in producing condensation, and the substance is 

 specially interesting to me because of this property. Cf. Bulletin No. 12, U.S. Weather Bureau, 

 Washington, 1895, 



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