Galvanic Experiments. 55 



•ment of oxygenated muriatic acid gas, and converts itself 

 almost instanily into luna cornea. In employing for thL$ 

 experiment crystals instead of powder, there is heard even at 

 a distance a strong crackling. 



You can obtain in the same manner very quickly the ' 

 brown oxide of lead. This oxide takes the shape of a little 

 scooped out channel. It has a very brilliant metallic ap- 

 pearance, and conducts electricity very well. The brown 

 oxide of lead with muriatic acid, even in cold, also throws 

 up vapours of oxygenated muriatic acid, but not nearly in 

 the same abundance as hvperoxide of silver. 



Other metals afforded me similar producjts, but I have 

 not yet had time to examine them. 



In like manner as silver allows itself to hyperoxidate, it 

 allows itself to hydrogenatc by the pile. You obtain the 

 hydrogenated silver in decomposing by the gold wire, or by 

 the negative silver of the pile, a solution diluted so suffi 

 ciently that thedisengagcdhvdrjgen shall be in greater quan- 

 tity .than is necessary to deoxidate the silver. The superabun- 

 dant hydrogen combines with the metal, and forms a com- 

 posite of the same colour, which deposits itself under the 

 appearance of a black magma, of a spunge-like body, or of 

 beautiful dendritic forms, and which is the true hydrogenated 

 silver. 



Priestley knew this substance, and gave it the name of 

 dephlogisticated silver. Bucholz had also obtained it, and 

 regarded it as sih'cr inoompletely reduced. But by heat one 

 may disengage hydrogen under the form of gas; after which 

 there remains reduced silver. 



I expect to obtain violent detonations from the mutual 

 reaction of hvpcroxidated silver and hydrogen. Copper is 

 hydrogenated under the same circumstances, and t^kes a 

 blue colour, witli the most beautiful and various shades. 



The same hydrogenafion succeeded equally well in my 

 experiments with tin. 



I have not vet examined the black precipitate of 

 gold which is obtained at the wire of the negative pole 

 of the pile. Silver, copper, and tin take the highest degrees 

 of hydiogenationbv expo-surc in a very diluted stale to strong 

 piles havinsi gold wires from tlu'ee-quarters of a line to one 

 line in thickness; and the higliest degree of hydrogenation, 

 chiefly for silver, appeared to constitute the gaseous state. 

 VVe know alre*ady the <::i^i'Uis state of the highest degree 

 of livdroiitnation of ntosl other metals. 



D 4 X. Che- 



