418 



metals constituting the battery, he found that no appreciable change 

 was caused in the antimony by a current maintained for four months, 

 and strong enough to cause, in 164 days, the deposition of a quan- 

 tity of copper in the voltameter, equal to the weight of the battery. 

 But the junctures of the bismuth and antimony, which were sol- 

 dered by pure bismuth, presented an important change, even in 

 thirty or forty days, — the bismuth soldering having undergone a 

 species of disintegration, so that the antimonial bar was easily sepa- 

 rated, and the surface of the bismuth lost its ci'ystalline appearance, 

 and might be rubbed off in the form of a fine powder. The author 

 proved, that this change could not be the effect merely of the heat 

 to which the metals were exposed, but is truly an electric pheno- 

 menon. Changes were also found to be effected, by long-continued 

 electric currents, in the specific gravity of the metals. Antimony 

 had its density raised, after exposure for twenty-two days to a ther- 

 mo-electric current, from 6.645 to 6.670 ; and the density of bis- 

 muth was diminished from 9.853 to 9.838. 



In pursuing his expei'iments with hydi-o-currents, he found, that 

 the elimination of hydrogen from a copper wire soon comes to an 

 end under the influence of pressure caused by the accumulation of 

 gas in a hermetically sealed space around the wire, while the depo- 

 sition of copper goes on. By hydro-currents, aided by pressure, he 

 obtained leaf-like deposits of metal, in solutions of common salt, with 

 poles of copper, tin, silver, and zinc, and pulverulent deposits with 

 gold, mercury, antimony, cobalt, platinum, and arsenic. But when 

 iron, bismuth, cadmium, and nickel were used, no deposition took 

 place, — the hydrogen continuing to be disengaged, till the voltame- 

 ter burst. 



To these investigations the author added some experiments on 

 the effects of quick and slow cooling, in altering the densities of 

 metals. He found, that antimony loses in density by sudden cool- 

 ing ; that this metal, and also bismuth, do not gain in density by 

 slow cooling; that by this process the density of lead, tin, and zinc 

 is increased ; that copper and silver are densest when allowed to 

 cool slowly ; that iron undergoes no change by slow cooling, un- 

 less first heated very strongly, in which case its density is diminished ; 

 and that steel loses in density by the process of hardening, but does 

 not lose by repeated heating. 



Lastly, in conformity with the experiments of Bequerel, on the 

 developement of electric currents, by sudden alterations in the den- 

 sity of metals, the author found, that, when the density of gold, pla- 



