244 Dr Wilson on the Decomposition of Water hy Platinum 



gives no traces of arsenic, although arseniate of copper m 

 associated with it in the specimens. The residue is a dark 

 reddish slag or globule. 



The crystals are not soluble in boiling- water, but dissolve 

 entirely, and pretty readily, in nitric or muriatic acid, espe- 

 cially by the aid of gentle heat. The solutions have the 

 colour belonging to copper solutions, and in the act of dis- 

 solving, a very few bubbles of gas may be observed to arise, 

 indicating probably the presence of a minute quantity of car- 

 bonate. The solutions yield, with barytic salts, a white pre- 

 cipitate insoluble in acids ; and the nitric solution gives, with 

 nitrate of silver, a white and curdy precipitate, insoluble in 

 acids or water, but dissolved by ammonia. Ammonia, in ex- 

 cess, added to the original solution, gives the fine deep blue 

 of copper. 



These appearances, in conjunction with the blow-pipe re- 

 actions, are sufficient to shew that the constituents of the 

 mineral are sulphuric acid, chlorine, copper, and a little wa- 

 ter. I had not enough of material to determine the propor- 

 tions of these constituents, but there can be no doubt that 

 the mineral consists essentially of sulphate and chloride of 

 copper, with a little water. Whether the copper salts are 

 neutral or basic, it is impossible to say. The chloride is ap- 

 parently the more abundant of the two salts. As above 

 stated, there seems also to be a trace of carbonate. 



On the Decomposition of Water hy Platinum and the Black 

 Oxide of Iron at a white heat, with some observations on the 

 theory of Mr Grovels Experiments. By GEORGE Wilson, 

 M.D., Lecturer on Chemistry in Edinburgh. Communi- 

 cated by the Royal Scottish Society of Arts.* 



The remarkable discovery recently made public by Mr Grove, 

 that water in certain circumstances, when raised to a white heat, is 

 resolved into its constituent gases, has naturally excited much at- 

 tention. It furnished the unexpected confirmation of the truth of 

 an opinion expressed by James Watt so far back as 1783, that if 

 steam could be made red hot [white hot] so that all its latent heat 



* Read before the Royal Scottish Society of Arts, 10th May 1847. This 

 paper was previouply communicated to the Chemical Society of London, in 

 whose Tranpactions for 1847 it was published. G. Vv'iLSOK. 



