66 On the Alloys of Steel. [1820. 



and beautiful surface appeared, the steel and platinum forming 

 dark and white clouds : if this can he effected with very fine 

 wires, a damasked surface will be obtained of exquisite beauty. 

 This experiment, made to ascertain the welding property of 

 platinum, is only named here in consequence of observing that 

 some of the largest of the steel clouds had much the appear- 

 ance of being alloyed with a portion of the platinum. A more 

 correct survey of the surface, by a high magnifying power, went 

 far to confirm this curious fact : some more direct experiments 

 are proposed to be made on this apparent alloy by cementation. 

 The alloys of steel with platinum, when both are in a state 

 of fusion, are very perfect, in every proportion that has been 

 tried. Equal parts by weight form a beautiful alloy, which 

 takes a fine polish, and does not tarnish ; the colour is the 

 finest imaginable for a mirror. The specific gravity of this 

 beautiful compound is 9*862. 



90 of platinum with 20 of steel gave also a perfect alloy, 

 which has no disposition to tarnish ; the specific gravity 15*88 : 

 both these buttons are malleable, but have not yet been applied 

 to any specific purpose. 



10 of platinum to 80 of steel formed an excellent alloy. This 

 was ground and very highly polished, to be tried as a mirror ; 

 a fine damask, however, renders it quite unfit for that purpose. 

 The proportions of platinum that appear to improve steel 

 for edge instruments, are from 1 to 3 per cent. Experience 

 does not yet enable us to state the exact proportion that forms 

 the best possible alloy of these metals ; 1*5 per cent, will pro- 

 bably be very nearly right. At the time of combining 10 of 

 platinum with 80 steel, with a view to a mirror, the same pro- 

 portions were tried with nickel and steel; this too had the 

 damask, and consequently was unfit for its intention. It is 

 curious to observe the difference between these two alloys, as 

 to susceptibility for oxygen. The platinum and steel, after 

 laying many months, had not a spot on its surface, while that 

 with nickel was covered with rust ; they were in every respect 

 left under similar circumstances. This is given as an instance, 

 showing that nickel with steel is much more subject to oxida- 

 tion than when combined with iron. 



The alloys of steel with rhodium are likely to prove highly 

 valuable. The scarcity of that metal must, however, operate 



