420 M. BECQUEREL ON CHEMICAL DECOMPOSITION AND 



pair, the particles of the solution, at the instant when they are set in 

 motion by the chemical action, being then in their nascent state, are 

 most disposed to obey the action of the current produced by the pair. 

 We have already cited examples in confirmation of this fact, but we 

 shall have occasion hereafter to notice a still greater number of them. 



Of the Formation of Metallic Oxides by Voltaic Action. 



Gold. — It was long supposed that gold was converted into a purple 

 oxide by means of electric discharges ; but it appears that this state is 

 only the effect of the extreme division of its parts, as it cannot be admitted 

 that it is oxidized at the temperature at which its oxide is commonly 

 reduced. It tends to confirm this conjecture, that when gold is preci- 

 pitated from a very weak solution, we likewise obtain a purple powder 

 by means of bodies which reduce its oxide. 



Iridium. — By exposing iridium to the discharge of a very powerful 

 electric battery, Children succeeded in reducing this metal to a white 

 globule, which was very brilliant and yet porous ; but he never could 

 oxidize it. 



Silver. — This metal when in contact with the air cannot be oxidized 

 at any temperature; but it is found capable of oxidation when exposed 

 in very thin leaves to the action of a very powerful battery. 



It may be obtained also in the state of hyper-oxide, a compound for 

 the discovery of which we are indebted to Ritter. It deposits itself on 

 the positive conductor of a pile, when that is discharged through a 

 weak solution of silver, in long crystalline needles crossed by three or 

 four lines possessing a metallic brilliancy. With a slow action it is ob- 

 tained in very regular and well-defined tetrahedrons. When subjected 

 to the action of hydrochloric acid, this compound gives out oxygen, and 

 is transformed into chloride of silver ; under the action of ammonia it is 

 decomposed and gives out azote, and when mixed with phosphorus it 

 detonates under the hammer. It decrepitates by heat, is decomposed, 

 and produces pure silver. 



Mercury. — When a very powerful electric pile is discharged through 

 a very small globule of mercury, the globule is driven in all directions, 

 becomes oxidi>,ed, and produces red sparks. 



Palladium is not oxided at the positive pole of the pile. 



Antimony. — When a piece of antimony is employed as a positive con- 

 ductor in order to decompose water, gray flakes are detached from its 

 surface; these, under the action of hydrochloric acid, are transformed 

 into antimony which remains, and into oxide of antimony which is dis- 

 solved. The flakes appear to be a suboxide. 

 • Zinc and the oxidable metals are easilv oxidized under voltaic influ- 



