216 Mr. Y. H. Veley. The Conditions of the [June 6, 



V. " The Conditions of the Reaction between Copper and 

 Nitric Acid." By V. H. Veley, M.A., University Museum, 

 Oxford. Communicated by Professor Odling, F.R.S. 

 Received May 13, 1889. 



Introduction. 



About fifty years ago De La Rive* observed that pure metallic zinc 

 but slowly enters into reaction with dilute sulphuric acid ; shortly 

 afterwards Faraday f confirmed this observation in the case of amal- 

 gamated zinc. In the course of some investigations on the equivalent 

 of this metal, Ramsay and Reynolds^ failed to obtain any hydrogen 

 from sulphuric acid and samples of zinc which they had purified by 

 every possible precaution. Thus the evolution of hydrogen from 

 zinc and sulphuric acid depends initially upon the presence of some 

 third substance, be it an impurity of the acid or of the metal. 



Similarly Russell§ has also observed that metallic silver is slowly 

 attacked by nitric acid freed from any considerable quantity of 

 nitrous acid, and that the rate with which the change proceeds de- 

 pends upon the proportion of nitrous acid present. 



Reactions between Copper and Nitric Acid. 



The changes which take place when metallic copper is dissolved in 

 nitric acid have attracted the attention of a number of investigators ; 

 the complexity of these changes and their almost infinite variety pro- 

 duced by slight variations of the conditions, are evidenced by the 

 elaborate researches of Deville,|| Armstrong^]" with Acworth and 

 Divers.** In the present communication I have the honour of laying 

 before the Royal Society a short and preliminary account of some 

 experiments on the conditions necessary for a reaction to take place 

 between metallic copper and nitric acid. 



The Methods of Experiment. 



By means of a mechanical device, described fully in another paper 

 before the Chemical Society, spheres of the purest electrotype copper 

 procurable were placed on a small glass dish which was kept con- 

 tinually revolved in dilute nitric acid ; a fairly uniform current of 



* ' Annales de Cliimie,' vol. 43, 1830, p. 425. 

 f ' Experimental Researches,' Series VII, p. 863. 

 % ' Chem. Soc. Journ.,' 1887 (Trans.), p. 854. 

 § ' Chem. Soc. Journ.,' 1874, p. 3. 

 || ' Compt. Rend.,' 70, pp. 20 and 550. 

 T[ 1 Chem. Soc. Journ.,' 1877, p. 54. 

 ** £ Chem. Soc. Journ.,' 1883, p. 443. 



