2 JOURNAL o^ The: 



the same however. In making known the latter, I feel 

 at liberty to give the results of my work, as indepen- 

 dent corroboration is of some value. 



The reactions which take place when copper is 

 treated with concentrated sulphuric acid may be divided 

 into primary and secondary. 



Primary: 



(1) Cu+2H,S04 = CuS04 + SO,+2H30. 

 This may be regarded as taking place in two steps: 



(a) Cu+HoSO,=CuSO,+H,, 



(b) H,+H,S0,-S0,+4H,0. 



Still no h3^drogen could be detected in the gas given off. 

 (2) 5Cu+4H2SO, = Cu,S+3CuSO,+4H,0. 

 Secondary: 



(l)Cu2S+2H,SO, = CuS+CuS04 + S02+2H20, 

 (2) CuS+2H2SO, = CuSO,+S+S02+2H20. 

 The experiments were carried out under various con- 

 ditions of temperature and time, exposure of the metal 

 to the action of the acid, and varying proportions of 

 metal and acid. The copper ribbon used was cut into 

 small pieces one cm. wide by two to three cm. long. 

 Concentrated c. p. sulphuric acid, 1.84 sp. gr. was 

 used. Each experiment, except where noted, was car- 

 ried out in a flask in which the air had been displaced 

 by a neutral gas, hydrogen or carbon dioxide. The 

 evolved sulphur dioxide was led through a strong 

 solution of sodium hydroxide and the sulphite formed 

 titrated with a standard iodine solution or oxidized by 

 ])roniine, and the sulphuric acid determined gravime- 

 tricalh^ A rapid stream of the inert gas was driven 

 through the apparatus just at the close of the experi- 



1 J. Loiid. CluMii. Soc. Trans.. 1878. p. 112. 



