171 the Silver Mines of Guadalcanal. 337 



means of aquafortis, or the nitric acid of commerce, which 

 dissolved the silver and left the platina : I washed the latter 

 and melted it a^ain, in order to give it a metallic lustre. 



5. As the lead which exists naturally in the first metallic 

 button is not in a sufficient quantity for taking up all the 

 copper in the cupellation, I submitted this metal a second 

 time to the same operation with a new quantity of lead.. 



6. Asj on the contrary, the quantity of silver is too small 

 to permit the aquafortis to attack the alloy, I added, as 

 when gold is to be separated, a new portion of this metal. 



7. I ouoht to say, that if we employ aquafortis a little con- 

 centrated, it dissolves at the ?ame time with the silver a por- 

 tion of platina, which may be easily perceived by the brown 

 colour assumed by the solution. 



If platina exists in the gray ore of Guadalcanal in a pro- 

 portion which admits of its being turned to advantage, it 

 cannot be doubted, after the above experiments, that we 

 must dissolve it by means of aquafortis, as practised when 

 we extract gold from silver ores ; and even if we should have 

 no occasion to do this with respect to the platina, we must 

 always do it in order to procure the silver out of it ; for, 

 whatever process is employed, these two metals are united, 

 on account of the similitude of their properties. 



Platina seems to exist in the metallic state in these ores ; 

 for the simple acids do not dissolve the smallest quantity of 

 it, and it is always found among the silex and sulphur when 

 the former forms part of the matrix ; it was even on exa- 

 mining these residues of ores, treated successively by the 

 nitric and nuiriatic acids, that I first perceived the platina. 



What is remarkable here is, that none of the four metals 

 newly discovered, and which attend the plalina of the ores 

 of Peru, are to be found in those of Spain. This considera- 

 tion is of great importance, since it will have a great deal of 

 influence upon the methods of extracting this metal, and since 

 it gives hopes of obtaining it in a state of purity, which we 

 cannot obtain in the platina of Peru, except with great ex- 

 pense and alter many ditficult experiments. 



If these hopes are realised, as every thing inclines us to 



think they will be, we shall have a precious metal in Europe, 



Y 2 and 



