104 Dr. Wollaston on a Method of 



The specific gravity of platina, drawn into fine wire, from a 

 button which had been completely fused by the late Dr. E. 

 D. Clarke, with an oxy-hydrogen blowpipe, I found to be 

 21.16. The aggregate specific gravity of the cake of metallic 

 mud, when first introduced into the barrel, exclusively of 

 moisture, is about 4.3 ; when taken from the press, is about 

 10. That of the cake fully contracted, on being taken out of 

 the wind-furnace before forging, is from 17 to 17.7. The mean 

 specific gravity of the platina, after forging, is about 21.25, 

 although that of some rods, after being drawn, is 21.4 : but 

 that of fine platina wire, determined by comparing the weight 

 of a given length of it with the weight of an equal length of 

 gold wire drawn through the same hole, I find to be 21.5, 

 which is the maximum specific gravity that we can well expect 

 to be given to platina. 



The mean tenacity, determined by the weights required to 

 break them, of two fine platina wires, the one of -j-Jq-q, the 

 other of y^Vff of an inch in diameter, reduced to the standard 

 of a wire -j^th of an inch in diameter, 1 found to be 409 

 pounds ; and the mean tenacity of eleven wires, beginning 

 with ^oo anc * ending with ^.^o of an inch, reduced to the 

 former standard, I found to be 589 pounds ; the maximum of 

 these eleven cases being 645 pounds, and the minimum 480 

 pounds. The coarsest and the finest wire which I tried pre- 

 sent exceptions, since a wire of T3 ^ of an inch gave 290 

 pounds, and a wire of g-Tr.&Tnr of an inch, 190 pounds. If we 

 take 590 pounds, as determined by the eleven consecutive 

 trials, to be the measure of the tenacity of the platina prepared 

 by the processes above described, and consider that the tenacity 

 of gold wire, reduced to the same standard, is about 500, and 

 that of iron-wire 600, we shall have full reason to be satisfied 

 with the processes detailed in the present paper, by which pla- 

 tina has been rendered malleable. 



To this paper I beg to subjoin an account of some processes 

 relating to two of the metals which are found in the ore of 

 platina. 



To obtain malleable palladium, the residuum obtained from 

 burning the prussiate of that metal is to be combined with 



