KLISHA MITCHELL SCIENTIFIC SOCIETY. ^ 



sulphuric acid in a flask provided with a loug- outlet 

 tube, much of the sulphur will be seen to creep up the 

 sides of the flask, and some sublimed even into the 

 tube, which shows that the state of affairs observed 

 may be attained without any trace of hydrogen sul- 

 phide being present. 



COPPER OXYSULPHIDE. 



Contradictor}^ evidence to what has been stated above 

 was found in one case where the insoluble residue 

 approximated Cu0.2Cu2S in composition. This is one 

 of the ox^'sulphides stated b}^ Maumene to exist in the 

 black residue. The acid was heated to 250*^ C. in an 

 Erlenmeyer flask. The air was not removed by an 

 inert gas. The copper was suspended in long strips, 

 only a third of which was immersed in the acid, the 

 other part being exposed to the air. 



The black residue formed under these conditions gave 

 on analysis: 



Calculated for 

 Found. CUO.2CU2S. 



Sulphur 16.16 16.15 



OxYg-en 3.54 4.03 



Copper undetermined 79.82 



Schuster^ found that copper was acted on by dilute 

 sulphuric acid only in the presence of atmospheric 

 ox3^gen. Traube- noted that copper was not oxidized 

 in moist air, but was slowlv in the presence of dilute 

 sulphuric acid. Although copper is unable to decom- 

 pose sulphuric acid at ordinary temperatures (accord- 

 ing to Traube) its affinity for SO^ and that of hydrogen 

 for ox3^gen are together sufficient to cause such a decom- 

 position, the probable reaction being: 



1 Proc. Ro.v. Soc. 55, 84; Ber. d. chem. Ges., 28. 219. 



2 Ber. d. chem. Ges.. 18. 1887-1890. 



3 Loc. cit.. p. 138. 



