250 Prof. E. Wartmann's^wr/// Memoir on Induction. 



to be disengaged, turned black in several places: then a series 

 oi luminous spar/cles, and lastly real sparks of a bright yellow 

 glittered on the whole immersed part of the platina wire. At 

 the same time the induced wire B was heated around the reel, 

 the metallic pieces of the rheotrope rose in temperature, and 

 the upper sides of the glass, not filled whh the albumen, were 

 coated with aqueous vapour. 



140. This remarkable phaenomenon is doubtless compli- 

 cated. The coruscations do not dart from one wire to the other 

 in the liquid ; they are seen along the wire. I thought at 

 first that the combustion (for it was such) only took place on 

 one of the electrodes (139.) ; but on repeating the experiment 

 many times, I saw it alternate on both of them according 

 as I reversed the poles of the battery, or present itself first 

 upon one wire, then upon the other, without the direction of 

 the current being changed ; or lastly appear upon only one 

 of them, whatever changes were made in the positions of the 

 rheophori and the extremities of the induced circuit. I attri- 

 bute this latter case, which only occurred when the surface of 

 the albumen was covered with a layer of aether, to the differ- 

 ence of the conditions of contact of the two platina electrodes 

 with the liquid : one, in fact, was then only covered with a 

 slight coagulum, whilst the other gave rise to a considerable 

 quantity of gas. These gases were collected on the aether in 

 a tube traversed by a [)latina wire cemented at its top. They 

 presented neither free carbonic acid, nor oxygen, nor hy- 

 drogen. I think that they were a mixture of oxide of carbon 

 and carburetted hydrogens. 



HI. The albumen solidified around platina conductors 

 acquires the consistence of very soft glue; it is ductile, brown- 

 ish, even blackish, and diffuses a marked odour of burnt horn 

 or phosphoretted hydrogen. The platina does not take the 

 pulverulent appearance nor black colour which are communi- 

 cated to it by discontinuous alternate currents in other media; 

 it preserves its metallic appearance. With the assistance of 

 Prof. Marignac I analysed the coagulum; it contained no 

 trace of platina. There is therefore here no catalytic action. 



142. These various remarks lead me to think that, in cir- 

 cumstances of imperfect conductibility of the albumen, and of 

 great power in the induced currents employed, the immersed 

 wires become heated when the coating of coagulum and of 

 gaseous bubbles has put a new obstacle to the passage of the 

 alternate currents (an obstacle rendered evident by the eleva- 

 tion of temperature of the external circuits), whence results a 

 true igneous decomposition and a burning, under the influence 

 of oxygen in a nascent state, of combustible elements exposed. 



