84 Action of ('< 'I'hnte, $c., on )f>'t<dlic Copper. 



" Note on the Action of Copper Sulphate and Sulphuric Acid 

 011 Metallic Copper." By ARTHUR SCHUSTKK, F.K.S. Re- 

 ceived November 14, Read December 7, 1893. 



Mr. Gannon in the foregoing paper refers to some unpublished 

 experiments made by me a few years ago. These experiments 

 were conducted for the purpose of satisfying myself that, as 

 seemed a priori probable, the diminution of weight observed when 

 metallic copper is exposed to the action of sulphuric acid or sulphate 

 of copper is due to the presence of free oxygen in the liquid. Copper 

 gauze was taken in order to deal with as large a surface as possible, and 

 rolled up so as to fit into a piece of glass tubing. After the copper had 

 been caref ally washed, dried, and ignited in hydrogen, it was immersed 

 in dilute sulphuric acid, the air above the acid was removed as far as 

 possible, and the tube containing the gauze was then sealed hermeti- 

 cally. At the end of a fortnight a few tubes prepared in this way 

 were opened and weighed after being subjected to exactly the same 

 treatment as previous to immersion, that is to say, the copper was 

 washed, dried, and ignited in hydrogen. The diminution in weight 

 observed under these circumstances was insignificant. I cannot, un- 

 fortunately, now find the record of the actual weighings, but the 

 quantities involved were about the same as in the next set of experi- 

 ments. On January 26, 1891, four spirals of copper gauze were placed 

 in a solution containing 20 per cent, of cnpric sulphate, 5 or 10 

 per cent, by weight of sulphuric acid being added to the aqueous 

 solution. The conditions thus approximated to the solutions which 

 are used in the electrolysis of copper. The tubes were exhausted 

 and sealed up : two of them were opened on February 2, and the two 

 remaining ones on February 9 ; the weighings were taken after drying 

 and ignition in hydrogen. The results are shown in the accompany- 

 ing table : 



It will be seen that the diminution in weight is quite insignificant 

 compared to what takes place in the presence of air, and may be due 

 to some remnant of oxygen left. The late Mr. Hoskyns Abrahall, 

 however, suggested that it might also be due to the formation of 

 copper sulphide ; and this suggestion was supported by the fact that 

 traces of sulphuretted hydrogen were given up when the copper, after 



