214 



ANNUAL OF SCIENTIFIC DISCOVERY. 



OH Bronze Alloys. 





The results obtained from this series of alloys lead to several conclusions 

 deserving; our notice. First, the marked softness of all the alloys containing 

 an excess of tin; secondly, the extraordinary fact that an increased quantity 

 of so malleable a metal as copper should so suddenly render the alloy brittle, 

 for the 

 Alloy Cu Sno, or 



.PP er > 2 J; 2 J 1 is not brittle. 



Tin, <o'<9 j 



whilst the alloy Cu Sn, or 



Copper, 34-98 \ . . ..., 



Tin,. 65 02 ) L 



Therefore, the addition of 14 per cent, of copper renders a bronze alloy brit- 

 tle. This curious fact is observed in all the alloys with excess of copper, 

 Sn Cii2, Sn Cu3, Sn Cu 4 , Sn Cu 5 , until we arrive at one containing a great 

 excess of copper, viz., the alloy Sn Cuio, consisting of copper 84'08 and tin 

 1-3 32, when the brittleness ceases; but, strange to say, this alloy, which con- 

 tains four-fifths of its weight of copper, is, notwithstanding, nearly as hard 

 as iron. This remarkable influence of copper in the bronze alloys is also 

 visible in those composed of 



Sn Cu 15 , containing 88-97 of copper. 



Sn Cu 



1:0, 



c< 



u 



91-49 

 93-17 



Sn Cu.,., 



Copper acquires such an increased degree of hardness by being alloyed 

 with tin or zinc, that we thought it interesting to ascertain if alloys com- 

 posed of these two metals would also have a greater degree of hardness than 

 that indicated by theory; w r e accordingly had a series of alloys prepared in 

 equivalent quantities, and these are the results arrived at : 



