of rendering Platina malleable. 7 



to platina complete malleability, will best be estimated by 

 comparing the metal thus obtained, in respect of its specific 

 gravity, with platina which has undergone complete fusion ; 

 and by comparing it, in respect of its tenacity, with other me- 

 tals possessing that quality in the greatest perfection. 



The specific gi'avity 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 intx'oduced 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 speci- 

 fic gravity of the platina, after forging, is about 21*25, al- 

 though 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 -^-qj^-j^, the 

 other of 3 oVo of an inch in diameter, reduced to the standard 

 of a wire J^th of an inch in diameter, I found to be 409 pounds ; 

 and the mean tenacity of 1 1 wires, beginning with 4 g-^^ ^ and 

 ending with 2 j^^ y of an inch, reduced to the former standard, 

 I found to be 589 pounds ; the maximum of these 1 1 cases 

 being 645 pounds, and the minimum 480 pounds. The coarsest 

 and the finest wire which I tried, present exceptions, since a 

 wire of xjou <^f ^^^ i"'^^^ g^^^ 290 pounds, and a wire of ^^.L^jj 

 of an inch, 190 pounds. If we take 590 pounds, as deter- 

 mined by the 1 1 consecutive trials, to be the measure of the 

 tenacity of the platina prepared by the processes above de- 

 scribed, 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 platina has been ren- 

 dered malleable. 



To this paper I beg to subjoin an account of some pro- 

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

 ore of platina. 



To obtain malleal)le palladium, the residuum obtained from 

 burning the prussiate of that metal is to be combined with 

 sulphur, and eacli cake of tiic sulphurct, after being fused, is 



(o 



