T H E 



LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



AUGUST 1839. 



XVII. On the Inaction of Amalgamated Zinc in acidulated 

 Water. Bj/ W. R. Grove, Esq., M.A., M.R.I.* 



IT is a well known fact, that the common zinc of commerce* 

 when immersed in water acidulated by sulphuric, phos- 

 phoric, or muriatic acid, is rapidly dissolved, evolving tor- 

 rents of hydrogen gas, while zinc with the surfoce amalga- 

 mated, remains inactive, under similar circumstances, unless 

 touched by another metal placed in the same solution, in 

 which case hydrogen, amounting to the full equivalent of the 

 oxygen which unites with the zinc, is evolved from the surface 

 of the associated metal, and the zinc is tranquilly dissolved. 



M. De la Rive observed, that pure zinc is much less vi- 

 gorously attacked by diluted acid than commercial zinc, 

 and has thence, after a careful experimental investigation, 

 concluded, that the evolution of gas by common zinc arises 

 from the circumstance of its adulteration by other metals ; 

 thus an infinity of minute voltaic circles is established, the 

 particles of zinc being oxidated, while those of the more ne- 

 gative metals evolve hydrogen {Bib. Univ. 1830). This ex- 

 planation does not apply to the inactivity of amalgamated zinc, 

 for as M. Becquerel asks {Traite, vol. v. p. 8), " Why doeg 

 not mei'cury, which by its contact with zinc and acidulated 

 water must also form a voltaic combination, produce a similar 

 effect?" 



An accidental circumstance led me to some experiments 

 which I think give a satisfactory answer to this question ; the 



* Read before the Royal Academy of Sciences of Paris, on the 24th of 

 Jane, 1839 ; and now comnuinicated by the Author. 



P/iil. Mag, S. 3. Vol. 15. No. Ol-. Jug. 1839. G 



