1897.] Mr Townsend, Electrical Properties of Gases. 345 



Monday, 22 November, 1897. 

 Mr F. Darwin, President, in the Chair. 



The following communications were made to the Society : — 



(1) Partial Differential Equations of the Second Order. By 

 Professor Forsyth. 



This paper is printed in the Transactions, Vol. xvi. Part III. 



(2) Electrical Properties of Newly Prepared Gases. By 

 John S. Townsend, M.A., Cavendish Laboratory, Cambridge. 



(1) The experiments which are described in this paper form 

 a continuation to those which have already been published in the 

 Proceedings of the Cambridge Philosophical Society, Vol. ix. Pt. v. 

 It was there shown that the gases given off by the electrolysis of 

 sulphuric acid or caustic potash carry with them an electric charge, 

 a large percentage of which remains in the gas after it has been 

 bubbled through a liquid, and passed through glass wool to remove 

 the spray. Another property of these gases is their power of con- 

 densing moisture to form a cloud. No such cloud could be observed 

 in newly prepared gases unless they were charged, and further the 

 weight of the cloud was found to be proportional to the charge on 

 the gas. These results go to show that the condensation of the 

 moisture is connected with the charge, and the experiments 

 described in section 16 of the above paper, and in section 19 of 

 this paper prove that when the cloud is formed in a charged gas 

 the electrification resides on the drops forming the cloud. So that 

 we have definite proof of the fact that the drops are formed round 

 the carriers of the electric charge. 



(2) These results were used to find the charge on each carrier, 

 and it was found to coincide with what we can calculate as being 

 the atomic charge, on the supposition that at ordinary temperature 

 and pressure there are 10 20 molecules in each cubic centimetre of 

 a gas. The experiments giving the weight of the cloud corre- 

 sponding to the charge being of importance, were repeated by the 

 following method which gave the same proportionalities in the 

 different gases between the charge per c.c. and weight of cloud 

 per c.c, as were previously obtained. 



(3) The apparatus which was used is shown in figure 1. The 

 positively charged oxygen and hydrogen given off from a dilute 



