468 Mr. G. Matthey. On the Preparation of the [Apr. 3, 



ternationale, and the French Minister of War, I proceeded in the 

 following manner with the platinum and iridium prepared as described 

 above. 



Operating upon a charge of 450 ounces of platinum and 55 ounces 

 of iridium, I commenced by melting these metals together and casting 

 into an ingot of suitable shape, which I then cut into small pieces 

 with hydraulic machinery. After re-melting and retaining in a molten 

 condition under a powerful blast of oxygen and common gas for a 

 considerable time, I re-cast and forged at an intense white heat under 

 a steam hammer, the highly polished surfaces of which were cleaned 

 and polished after each series of blows — when sufficiently reduced it 

 was passed through bright polished steel rollers, cut into narrow 

 strips, and again slowly melted in a properly shaped mould, in which 

 it was allowed to cool. I thus obtained a mass of suitable shape for 

 forging, perfectly solid, homogeneous, free from fissures or air-holes, and 

 with a bright and clean surface at bottom and sides as at top. At the 

 first forging a bar was obtained 35 centims. long, 7*5 wide, 2*5 thick, 

 which weighed — 



In air 15*105 grms. 



In water at 70° F 14*405 „ 



Showing a density at zero of 21*522 



A third of the bar was cut off and the larger portion again forged to 

 a length of 95 centims., width 2*5> thickness 2*0, which weighed — 



In air 10*814 grms. 



In water at 60° F 10*315 „ 



Showing a density at zero of 21*648 



This was then passed through highly polished rolls until of a length 

 of 4,010 centims. 21 millims. in width, and 5 millims. thick, to 

 which a perfectly rectangular form was subsequently given by draw- 

 ing it through a series of plates, and thus prepared the rule was in a 

 condition to receive the beautiful polish of which this alloy is sus- 

 ceptible. 



After passing it through each hole the metal was annealed by 

 means of a jet of gas and oxygen to a heat just below melting point, 

 and each time throughout after forging, rolling, and drawing was 

 exposed to the action of melted borax, and boiled in concentrated 

 hydrochloric acid to remove any possible trace of adherent iron or 

 other impurity. 



A piece cut from the end and presented to the French Academy of 

 Science gave the following results * 



Weight in air 116*898 grms. 



„ water 111*469 „ 



Showing a density of. . 21*516 



