upon different Metals. H 



much resembled the amalgam formed by the electrization of 

 mercury in contact with ammonia. 



The experiment was frequently repeated, sometimes with the 

 substitution of some neutral salt for the acid, and always with 

 similar results. 



When the amalgam was laid upon filtering paper, the mois- 

 ture was gradually absorbed and evaporated, and the mercury 

 returned to the fluid state. 



EXPERIMENT XVII. 



The experiment was varied by filling a tube, which was 

 some inches longer, with the weak acid solution ; and after the 

 formation of the amalgam by agitation, inverting it in a cup of 

 mercury. Minute bubbles of gas were immediately seen rising 

 from the amalgam through the fluid, and collecting in the 

 upper part of the tube. Upon close examination, particles of 

 the spongy platinum could be discovered between the sides of 

 the glass and the mercurial paste, round which bubbles of 

 gas gradually accumulated, which gave the whole a honey- 

 combed appearance. These, as they increased in size, slowly 

 crept up the sides of the tube, till, reaching the fluid, they 

 rapidly ascended to the top. In twelve hours' time, nearly the 

 whole of the liquid had been expelled from the tube, and when 

 a light was applied to the gas it exploded. 



Some of the acetic solution, which had been frequently em- 

 ployed in repetitions of the experiment, was slowly evaporated, 

 and afforded crystals of prot-acetate of mercury. 



EXPERIMENT XVIII. 



I endeavoured, in vain, to produce analogous results, by 

 agitating amalgam of gold and other amalgams with diluted 

 acetic acid and solutions of neutral salts. No action was 

 apparent, and in no instance was anything like the frothy amal- 

 gam produced. 



Hence it appears that, when minutely divided platinum is 

 agitated with mercury, and moisture is present, an electrical 

 action takes place, which, when heightened by the addition of 

 a diluted acid, or the solution of a neutral salt, is sufficiently 

 energetic to decompose water and evolve hydrogen : the oxygen 



