Chemico- Galvanic Observations. 131 



(a) Hydrogenated Hydruret of Gold obtained by Galvanism. 

 'Conversion of this Compound into pure Gold, on which 

 depends the Weight as ivell as the Polarity of the Pieces 

 of Gold observed by Ritter. 



It was often remarked, that the metal wires employed to 

 galvanize pure water, formed blacker crusts on the negative 

 side than on the other. The better to study these effects the 

 author made use of well polished metal wires, which he 

 plunged in a glass tube an inch high, and containing nearly 

 an ounce of pure water; the wires communicating one with 

 the negative pole of the pile and the other with the positive ; 

 they both descended, at the distance of three lines from each 

 other, into the tube, which was closed at bottom. 



Pure gold, being more easily oxidated by this process than 

 other metals, may be more minutely examined. Jt was re- 

 marked that the wire on the negative side changed first; it was 

 covered with a black substance, which increased by degrees, 

 until the metal could be no longer recognised, and it was 

 changed in a few hours into a spongy substance very much 

 swelled. It sometimes presents itself under the appearance 

 of beautiful arborizations, formed of small threads, which are 

 implanted into one another. These intricate forms are not 

 observed, except when the great piles are weakened. The 

 water in which the wires are plunged remains pure, and does 

 not appear to contain any foreign substance. 



The author regards the black matter formed upon the 

 wire as being a hydruret of hydrogenated gold ; i. e. hydro- 

 genated gold combined with water. This compound is in- 

 odorous, and almost insipid. It blackens linen when first 

 thrown upon it, and it afterwards changes to a purple co- 

 lour, which it also occasions applied to the skin. 



Upon plunging into a vessel full of distilled water a 

 single gold wire, attached to the negative pole on the one 

 side, and on the other side a strip of moistened pasteboard 

 communicating with the positive pole, this particular mo- 

 dification of gold is not obtaintd ; a good deal of hydrogen 

 gas is liberated on the side of the metallic wire, and the 

 I 2 water 



