VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 47 



artists term it, clingy, to receive the impression of lines, figures, and letters, or 

 for instruments in which holes are to be drilled. The solution of this allay in 

 nitric acid was blue, like those of the preceding allays and old metals, but there 

 was no white deposit. 



Observation. — This is the proper place to observe that all the above allays, and 

 the gun metal, melted at a lower temperature than copper does ; and, as far as I 

 could determine, the temperature of fusion decreases as the proportion of tin in- 

 creases. The next experiments were made not only to satisfy myself, that if iron 

 had been an ingredient in the ancient metals, it must have been made appear by 

 the test employed ; but also to determine the question made by some chemists, 

 whether copper can be allayed by iron ; and to show, as others have asserted, the 

 allays of copper by iron, which were employed by the ancients. From the writings 

 of many able chemists I was inclined to suppose, that a malleable uniform metal 

 could not be composed of copper and iron, without the aid of an intermede. I 

 therefore, in the first place, used tin as the intermede. 



Some of these experiments next to be related may not be found immediately 



relative, but as they occurred in the course of investigation, and as I believe few 



experiments of the same kind have been published, perhaps they will be found useful. 



Exper. 15. 2000 grs. of tin were melted with ]000 grs. of steel,* by keeping the 



2 metals in a close crucible exposed to a pretty fierce fire of a melting furnace. An 

 allay was produced of a uniform metallic mass, of the colour of pewter, of a very 

 open grain, but uniform texture; which was as brittle, and not harder than certain 

 kinds of old bad pewter. 



Exper. 16. 1800 grs. of tin were melted with 600grs. of steel. This allay of 



3 parts of tin with 1 of steel was perfectly similar to the last allay of 2 parts of tin 

 with 1 of steel, excepting that the allay of this experiment was not so hard, and 

 was less brittle. Having thus prepared the steel for union with copper, by the me- 

 dium of tin, I added to it copper. 



Exper. 17. 600 grs. of the allay of exper. 15 were melted with 2400 grs. of 

 copper. This allay of 12 parts of copper with 2 parts of tin, and 1 part of steel, 

 resembled exactly the allay of 6 parts of copper with 1 of tin, in exper. 8, in the 

 colour and grain of the fracture ; in its polish, hardness, and brittleness. Its frac- 

 ture was of course of a slate-coloured hue, or dark grey, somewhat crystallized and 

 silvery. The fracture being inspected with a lens, the grain appeared finer or 

 shorter than that of the allay of 6 parts of copper with 1 of tin. 



The solution of this metal in nitric acid produced nitrous gaz, a blue solution, 

 and a white deposit; as occurred in the dissolution of the ancient metals, § 5, 

 p. 43, and of the allays of copper with tin, p. 44 — 4Q; but the result of the 

 examination of this blue solution and white deposit was different from that of the 

 ancient metals, and satisfied my mind completely, that if those metals had contained 

 iron, it must have been detected. 



* The steel employed was part of a file. Steel was preferred to iron, because it is fusible, but iron 

 is not.— Orig. 



