46 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6, 



than the celt, N° 3, and of course much more so than the other ancient metals. 

 This allay, on solution in nitric acid, yielded 20 per cent, of oxyde of tin. 



Exper. 8. 100 grs. of tin were melted with 600grs. of copper. This allay of 

 6 parts of copper with 1 of tin was harder than any of the above allays : and per- 

 haps it was harder and more brittle than any of the ancient metals. Its fracture 

 exhibited a still finer, brighter, silvery, and more crystallized grain than any of the 

 preceding allays. Nitric acid separated from this allay 22 per cent, of oxyde of tin. 



Exper. 9. 100 grs. of tin were melted with 400 grs. of copper. This allay of 4 

 parts of copper with 1 of tin was about as hard and brittle as some sorts of bell- 

 metal. Its fracture was still paler, finer grained, and silvery, than any of the pre- 

 ceding allays. Nitric'acid separated from this allay 27 per cent, of oxyde of tin. 



Exper. 10. 100 grs. of tin were melted with 300 grs. of copper. This allay of 

 3 parts of copper with 1 of tin, was much harder than any of the preceding ones. 

 It was also much more brittle, the fractured surface was quite smooth, and with- 

 out almost any grain at all. It was of a silvery hue, and resembled much an ingot 

 of a melted bell ; excepting that it was finer grained, and of a duller colour. 



Exper. 11. 100 grs. of tin were melted with 200 grs. of copper. This allay of 

 2 parts of copper with 1 of tin, was as brittle almost as glass. The fracture 

 showed no grain at all, being quite smooth. Its colour was more like that of 

 silver than any other metal. 



Exper. 1 2. The metal of which what are called brass guns are made, does not 

 in general contain a grain of zinc. They are made of an allay of about 10 to 12 

 or 13 parts of copper, with one part of tin. I found that the shavings of 1 of 

 these guns melted much more readily than copper. The ingot was not so hard, 

 but tougher than any of the above ancient metals. It possessed nearly the same 

 hardness and strength as the allay, in experiment 3, of 12 parts of copper by 1 of 

 tin. The colour of the polished surface, and the grain and colour of the fractured 

 surface, resembled pretty exactly that allay. Of course this gun metal is only a 

 little less hard and brittle than the celts, N° 1 and N° 2, but it resembles them 

 very exactly in the colour and texture of the grain. This gun metal afforded 

 nearly 13 per cent, of oxyde of tin, by means of nitric acid. 



Exper. 13. 20 grs. of tin and 10 grs. of zinc were melted with 800 grs. of 

 copper. This allay of 80 parts of copper with 2 parts of tin, and 1 part of zinc, 

 was a metal which had a very different aspect when polished, as well as when frac- 

 tured, from either copper, or any of the above allays, or any of the ancient me- 

 tals. For it had a rich yellowish or golden hue, and was nearly as tough, but a 

 little harder than copper. 



Exper. 14. 20 grs. of zinc were united by fusion with 800 grs. of copper. This 

 allay of 40 parts of copper with 1 part of zinc, was of a yellowish golden hue, 

 and of course was very different in its external appearance from the allays of copper 

 by tin. Like the allay of experiments 1st and 13th, it was too soft, and, as the 



