On Stratification in Electrical Discharges in vacuo. 239 



the group to which the element belongs, and the place which it 

 occupies in the solar atmosphere. 



April 8. — Joseph Dalton Hooker, C.B., President, in the Chair. 



The following paper was read : — 



" Experiments to ascertain the Cause of Stratification in Elec- 

 trical Discharges in vacuo" By Warren De La B,ue, Hugo W. 

 Miiller, and William Spottiswoode. 



Some results obtained in working with a chloride-of-silver battery 

 of 1080 cells in connexion with vacuum-tubes appear to be of 

 sufficient interest to induce us to communicate them to the Society, 

 in anticipation of the more detailed account of an investigation 

 which is now being prosecuted, and which it is intended to con- 

 tinue, shortly, with a battery of 5000 cells, and possibly with a far 

 greater number. 



The battery used up till now consists of 1080 cells, each being 

 formed of a glass tube 6 inches (15*23 centims.) long and f of an 

 inch (1*9 centim.) internal diameter ; these are closed with a vulca- 

 nized rubber stopper (cork), perforated eccentrically to permit the 

 insertion of a zinc rod, carefully amalgamated, j 3 ^- (0*48 centim.) of 

 an inch in diameter and 4*5 inches (11*43 centims.) long. The other 

 element consists of a flattened silver wire passing by the side of 

 the cork to the bottom of the tube and covered, at the upper part 

 above the chloride of silver and until it passes the stopper, with 

 thin sheet gutta percha for insulation, and to protect it from the 

 action of the sulphur in the vulcanized corks • these wires are -^ 

 of an inch (0*16 centim.) broad and 8 inches (20*32 centims.) long. 

 In the bottom of the tube is placed 225-25 grains (14*59 grms.) 

 chloride of silver in powder • this constitutes the electrolyte : above 

 the chloride of silver is poured a solution of common salt containing 

 25 grammes chloride of sodium to 1 litre (1752 grains to 1 gallon) 

 of water, to within about 1 inch (2*54 centims.) of the cork. 

 The connexion between adjoining cells is made by passing a short 

 piece of india-rubber tube over the zinc rod of one cell, and drawing 

 the silver wire of the next cell through it so as to press against 

 the zinc. The closing of the cells by means of a cork prevents the 

 evaporation of water, and not only avoids this serious inconveni- 

 ence, but also contributes to the effectiveness of the insulation. 

 The tubes are grouped in twenties in a sort of test-tube rack, 

 having four short ebonite feet, and the whole placed in a cabinet 

 2 ft. 7 in. (78*74 centims.) high, 2 ft. 7 in. wide, and 2 ft. 7 in. deep, 

 the top being covered with ebonite to facilitate working with the 

 apparatus, which is thus placed on it as an insulated table. 



The electromotive force of the battery, as compared with a 

 Daniell's (gravity) battery, was found to be as 1*03 to 1*, its in- 

 ternal resistance 70 ohms per cell, and it evolved 0*214 cub. centim. 

 (0*0131 cub. inches) mixed gas per minute when passed through a 

 mixture of 1 volume of sulphuric acid and 8 volumes of water in a 



* Compared with a Daniell's battery, in which the zinc is immersed in dilute 

 6ulphuric acid in a porous cell, its electromotive force is about 3 per cent, less 

 than the Daniell. 



