m CHEMICAL DISCOVERY AND INVENTION 



which fits on to a cylinder of soft iron with a hole bored along 

 the axis. A very narrow copper tube, only about ! mm. to 

 5 mm. in diameter, passes through this tube. The particles 

 entering are therefore protected from magnetic forces till emerg- 

 ing from the copper tube, they pass between the poles of the 

 electro magnet PP, or the plates EE, by which an electric field 

 can also be provided. The positive particles then strike on a 

 photographic plate and there record a series of parabolas which 

 depend on the gas or gases present in the tube. 



It appears that each of the curves corresponds to a different 

 atomic weight and that these ions are capable of carrying one, 

 two, three or more unit charges. The method therefore can be 

 used as the basis of a new method of analysis, and some very 

 remarkable results have been obtained. Thus among the gases 

 evolved from platinum by bombardment with cathode rays are 

 found not only atoms of hydrogen with one charge and molecules 

 of hydrogen with two charges, but particles of a gas which 

 appears to consist of an element with atomic weight 3, which is 

 either a previously unknown element or consists of hydrogen 

 associated into a molecule H 3 . 



Another strange result of this investigation is that it appears 

 possible to recognise temporary associations of atoms which are 

 so unstable that they are unknown to the chemist. Thus when 

 marsh gas CH 4 is used in the experimental tube fragments of 

 the molecule CH 3 , CH 2 , CH and C appear to be able to record 

 their presence on the photographic plate, although the life of 

 each cannot be longer than a very small fraction of a second. 



The discoveries which have thus resulted from a close study 

 of the effects of the electric discharge naturally suggest hypo- 

 theses as to the constitution of atoms and the nature of chemical 

 action. For the present it will be more convenient to postpone 

 any discussion of this fascinating subject till the history of the 

 elements and their known relations to one another has been 

 laid before the reader. 



Before closing this chapter which relates to the action of 

 electricity on gases in general it will be appropriate to give a 

 brief account of some phenomena connected with this subject 

 and brought about by the same agency in connection with the 

 element nitrogen. 



The investigation has been carried out by the Hon. R. J. 

 Strutt, professor of physics in the Imperial College of Science at 



