70 On the Alloys of Steel. [ 1 822. 



cible, and placed in the furnace, to attend to it while there, 

 and to suffer it to remain for some considerable time in a state 

 of thin fusion, previous to its being poured out into the mould. 

 The cast ingot was next, under the same superintendence, 

 taken to the tilting mill, where it was forged into bars of a 

 convenient size, at a temperature not higher than just to render 

 the metal sufficiently malleable under the tilt hammer. When 

 returned to us, it was subjected to examination both mechanical 

 and chemical, as well as compared with the similar products of 

 the laboratory. From the external appearance, as well as from 

 the texture of the part when broken by the blow of the hammer, 

 we were able to form a tolerably correct judgement as to its 

 general merits ; the hardness, toughness, and other properties 

 were further proved by severe trials, after being fashioned into 

 some instrument or tool, and properly hardened and tempered. 



It would prove tedious to enter into a detail of experiments 

 made in the Royal Institution ; a brief notice of them will at 

 present be sufficient. After making imitations of various spe- 

 cimens of meteoric iron, by fusing together pure iron and 

 nickel, in proportions of 3 to 10 per cent., we attempted 

 making an alloy of steel with silver, but failed, owing to a 

 superabundance of the latter metal ; it was found, after very 

 many trials, that only the J^Q^ P art f silver would combine 

 with steel, and when more was used a part of the silver was 

 found in the form of metallic dew, lining the top and sides of 

 the crucible : the fused button itself was a mere mechanical 

 mixture of the two metals, globules of silver being pressed out 

 of the mass by contraction in cooling, and more of these glo- 

 bules being forced out by the hammer in forging ; and further, 

 when the forged piece was examined, by dissecting it with 

 diluted sulphuric acid, threads or fibres of silver were seen 

 mixed with the steel, having something of the appearance of 

 steel and platinum when united by welding : but when the pro- 

 portion of silver was only j.Jo^ part, neither dew, globules, 

 nor fibres appeared, the metals being in a state of perfect 

 chemical combination, and the silver could only be detected 

 by a delicate chemical test. 



With platinum and rhodium, steel combines in every propor- 

 tion ; and this appears also to be the case with indium and 

 osmium: from 1 to 80 per cent, of platinum was perfectly 



