2^ ON TWO METALS, FOUND IN THE POWDER 



his work, Sur les Vegetaux, printed at Paris, 1787; bat un- 

 doubtedly this feclion had by fome means been overlooked. 

 All that I have to do at prefent, by way of reparation, is to 

 thank Dr. Thomfon for his information, and to declare that 

 paper of no value ; which in all probability will prove a fuf- 

 fitient apology to M. Ingenhouz. 



VII. 



On tivo Metals, found in the black Powder remaining after the 

 Solution of Platina. By Smithson Tknnant, Efq. F. R.S. 

 From the Philofophical Tranfuclions for 1 804. 



Introduflion, \J PON making fome experiments, laft fummer, on the black 

 to the experi-' powder which remains after the folution of platina, I obferved 

 ments made by that it did not, as was generally believed, confift chiefly of 

 D tils, plumbago, but contained fome unknown metallic ingredients. 



Intending to repeat my experiments with more attention during 

 the winter, I mentioned the refult of them to Sur Jofeph Banks, 

 together with my intention of communicating to the Royal 

 Society, my examination of this fubftance, as foon as it mould 

 appear in any degree fatisfa&ory. Two memoirs were after- 

 wards publifhed in France, on the fame fubjecf. ; one of them 

 by M. Defcotils, and the ethers by Meffrs. Vauquelin and 

 Fourcroy. M. Defcotils chiefly direels his attention to the 

 effects produced by this fubftance on the lolutions of platina. 

 He remarks, that a fmall portion of it is always taken up by 

 nitro-muriatic acid, during its a&ion on platina ; and, prin- 

 cipally from the obfervations he is thence enabled to make, he 

 infers, that it contains a new metal, which, among other pro- 

 perties, has that of giving a deep red colour to the precipitates 

 of platina. 

 and by Vauque- M. Vauquelin attempted a more direct analyfis of the fub- 

 ftance, and obtained from it the fame metal as that difcovered 

 by M. Defcotils. But neither of thefe chemifts have obferved, 

 that it contains alfo another metal, different from any hitherto 

 known. 

 Subfonce ob- The fubftance with which my experiments were made, was 

 /rains of^atiiu, ^ la ' ne( ^ ^ rom P^ at ' na which had been previoufly freed from 

 the fand and other impurities generally mixed with it ; fo that 



it 



