lional Jnstitution of CKrcat Britain- 



WEEKLY EVENING MEETING, 



Friday, January 21, 1881. 



William Bowman, Esq. LL.D. F.R.S. Vice-rresidciit, in the Chair. 



Warren De La Rue, Esq. M.A. D.C.L. F.R.S. Sec. R.T. 

 Cor. Mem. Inst. Fmnce, Hon. Mem. Irapl. Academy of St. Petersburg, &c. 



The Phenomena of the Electric Discharge with 14,400 Chloride of 



Silver Cells. 



For the last six years I have, in conjunction with my friend Dr. 

 Hugo Miillcr, been engaged with experiments on the electric dis- 

 charge, using as the source of electricity a constant voltaic battery 

 which we devised.* It is in principle the same as that invented by 

 Daniell, but in our battery a solid electrolyte, insoluble in water or a 

 weak saline solution, namely, chloride of silver, replaces the soluble 

 sulphate of copper, so that no porous cell is needed in the chloride of 

 silver battery. The results of our experiments my colleagues think 

 of sufficient interest to be brought under the notice of the Members of 

 the Royal Institution, and I will endeavour to make them as clear as 

 possible in the limited time at our disposal. I must, however, ask 

 your kind indulgence if I fail, as I have not the practice of lecturing. 

 It is true that it is not the first time that I have had the honour to 

 occupy this chair, which I did upwards of forty years ago.| 



I may as well commence by describing the tool which I am about 

 to use in the experiments : the diagram will help you to understand 

 it. The chloride of silver battery is made up as follows : A glass 

 tube IJ inch in diameter, 5.V inches long, and containing about 

 2 fluid ounces of liquid ; into this is fitted a paraffin stoj^per with two 

 holes perforated through it ; through one of these a zinc rod y\ inch 

 diameter and 5^ inches long is inserted, and fastened by melting a 

 little of the paraffin around it ; the other element is formed of a 

 flattened silver wire, which passes between the stopper and the glass ; 

 so that the metallic elements are zinc and silver. On the flattened 

 silver wire is cast the electrolyte — namely, a rod of chloride of silver 

 2], inches long and ^i- diameter, and the cell is charged through the 

 second perforation in the stopper with a solution of chloride of 

 ammonium containing 2| per cent, of salt (Fig. 1). When the circuit 

 is not closed — that is, when the silver element is not connected by 

 means of a conductor to the zinc, no action whatever takes place ; 

 and in proof of this I may state that I have a battery which was made 



* 'Phil. Trans.' Part L vol. clxix. pp. 55-121, pp. 155-241; vol. clxxi. 

 pp. G5-116. 



t May 19, 1837. 

 Vol. IX. (No. 73.) 2 k 



