210 On some Comlinations of Plaliva. 



development of its combinations. Hence its chemical 

 history is perhaps less known and more hmiled than that 

 of any other metal. In th£ Philosophical Magazine for 

 July, I have described some combinations of platina with 

 sulphur and phosphorus; in the present communication, 

 I shall enter into simie details relative to some other com- 

 pounds of this metal. I shall also venture, on the authority 

 of experiments, to controvert Sonne statements respecting the 

 oxides and salts of platina. I have to regret that other 

 engagements will not allow me leisure to complete the pre- 

 sent, together with other investigations I had begun ; but 

 I shall rather choose to bring them occasionally forward in 

 an imperfect state, than to withhold them entirely, in the 

 anticipation of a period which perhaps may never arrive. 



1. Of t lie Hydrosulphtiret of Platina. 



The compounds obtained by the agency of sulphuretted 

 hydrogen gas on acid solutions of the metals are but im- 

 perfectly known, they have not yet been examined with 

 precision j hence, as might be expected, there exists among 

 Chemists a diversity of opinion concerning their constitu- 

 tion. A minute investigation of this class of bodies would 

 serve to elucidate many chemical phaeaomena relating to the 

 metals, and, there is everv reason to believe, would furnish 

 novel and interesting results. It is not my intention to 

 enter into any details relativ'e to the nature of these bodies 

 in general, but simply to confine myself to the consideration 

 of the hydrosulphurst of platina. 



This substance may be obtained, by treating a solution 

 of platina with water impregnated with sulphuretted hy- 

 drogen gas J or by passing a current of gas through the 

 solution. After the gas has been passed for a short time 

 through the solution, the surface is covered with a thin 

 coating of a dark iron^ray colour, having the metallic 

 lustre; a quantity of it is also deposited at the bottom of 

 the vessel. As it readily undergoes chemical change in 

 the atmosphere ; when it is wanted for accurate experi- 

 ments, the best mode of procuring it seems to be that I 

 adopted, which will presently be mentioned. 



The hydrosulphurei of platina has been partially known 

 for some time ; but it has not I believe been described, nor 

 its composition determined. I do not think it has been at 

 »ll examined in a state oi purity. It has been considered 

 by 6ome chemists as metallic platina ; and Dr. Thomson in 

 his System of Chemistry states it as a distinguishing cha- 

 racter of platina, that it is precipitated by sulphuretted hy- 

 drogen 



