On some Comlwations qfPUtina. 97 1 



md acciirate mode of determining the composition of cer- 

 tain metallic oxides, and of thus reconciling the differences 

 which exist in the estimates of chemists. 



4. Of the Combinations of Platina with Chlorine. 



My cousin, Sir H. Davy, appears to have proved, that 

 in the present state of our knowledge, chlorine or oxymu- 

 riatic gas is a simple body, and like o.xygen it forms pecu- 

 liar compounds with metallic substances*. The com- 

 binations of platina with chlorine have not hitherto been 

 examined j they are not known in a separate state. Platina 

 appears to form two distinct compounds with chlorine, one* 

 soluble, the other insoluble in water. I have not examined . 

 the former, which appears to be produced in an impure 

 state, when a solution of muriate of platina is evaporated 

 to dryness, and to be precipitated in union with horn silver 

 by nitrate of silver. This-substance is very soluble in wa- 

 ter, and deliquescent. My experiments have been wholly 

 confined to the insoluble compound, which, as it is unaf- 

 fected by chlorine, may be presumed to contain the larger 

 proportion of this principle. In making the details connected 

 with the examination of this substance, I shall beg leave to 

 adopt the nomenclature suggested by Sir Humphry Davy. 

 Supposing the soluble compound to contain one proportion 

 of chlorine, and the insoluble compound two proportions; 

 the former will be called Plalinnne, and the latter P/a/i«a«a. 



Of Platinana. 



This substance has been imperfectly known for some 

 time, as the insoluble muriate of platina. In the state in 

 which it has been examined, it .-ppears to have been a 

 mixture of platinana with platinane, and has been supposed 

 to be a compound of muriatic acid, oxide of platina, and 

 water. 



When platina in a finely divided state is introduced into 

 a reiort filled with chlorine gas, no apparent action is pro- 

 duced ; on the application of heat, they slowly combine, 

 and a substance is formed, which passes from intermediate 

 •hades of brown to an olive colour, and there is a consider- 

 able absorption of the gas. This substance appears to be 

 precisely sin)ilar in external characters to that obtained by 

 a mode which will presently be described, l)ut it ditfcrs 

 from it materially as to the proportion of chlorine. 

 The combination in this instance is very partial, and 

 merely superficial. In the trials that I have made in this 



• Phil. Tram. 1809, p. .073. 



way. 



