McClki.lanu and Nolan — Ions Produced bij Pliosphnru^. 9 



may be that these ions are furnuMl in nihri' casi's of iuiiisatinu. One could 

 account for the fact that they liave not heen (jliserved Ky iw(] consiilerations. 

 Firstly, tliey are formed in such small (quantities that their presence would 

 be hard to detect, riiosphorus is one of the most active ionisation ajfeiits, 

 and so they are more readily observed with it. Secondly, a very lou',' time is 

 necessary for their formation. The time for formation \'ari(^s in diflerent 

 cases. It is interesting to note in this conne.xion that the ion of mobility 

 "OOOol appeared much sooner with phosphorus than with alcohol or mercury. 

 Accordingly we suggest that it is quite possible that in other cases of 

 ionisation these very large ions are formed in minute quantities at long 

 intervals after the ionisation has been formed. 



It might be objected that these ions of very low mobilities are not similar 

 to the ordinary large ions. It is well known that phosphorised air contains 

 a large quantity of very big nuclei. These very large ions might be supposed 

 to consist of large nuclei of some oxide of phosphorus carrying many times 

 the electronic charge. "We reject this view for two reasons. In the first 

 place, the continuity between these ions and the ions of higher mobilities 

 leads US' to believe that thej^ are formed in the same manner and are of the 

 same general nature. In the second place, one of these larger ions, that of 

 mobility "00015, has been observed in air bubbled through alcohol, and we 

 have no reason to believe that very large nuclei are produced when air is 

 ionised by bubbling. 



The large ion which occurs in the atmosphere has a mobility of the order 

 •0003 cm. per second. There has been a general opinion that there is a 

 certain degree of stability associated with the ion of this size. An ion of 

 this mobility was observed with phosphorus, but no special difference marked 

 it out from the other ions. Furthermore, we get ions larger than the 

 atmospheric ion, viz. the ions of mobilities "00015, "000085, "000053. As we 

 pointed out already, we have no proof that the ion of mobility "000053 is by 

 any means the final ion. It is remarkable that, in spite of its wide occurrence 

 and stability, the size associated with the mobility "0003 is not the largest 

 possible. 



We can place all the mobilities observed in a certahi number of classes. 

 The following are the means of the observations. Doubtful numbers are 

 excluded, and a few numbers not given in the paper are included in 

 calculating the means. 



"22 "092 "053 "028 "OlS -0074 



•0041 "0024 "0012 -00004 "00031 

 ■00015 •000085 "000053 



K.I. A. PKOC, VOL. XXXV, SECT. A. [2j 



