44 
This series of alloys presents several facts 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 Sn.,, or 
Copper 21.211 
Tin ... 78.79 J 
Whilst the alloy Cu Sn, or 
Copper 34.981 
Tin ... 65.02J 
Therefore the addition of 14 per cent, of Copper renders the 
Bronze Alloy brittle. This curious result is observed in all 
the alloys with excess of Copper, Sn Cug, Sn Cug, Sn Cuj, 
Sn Cuj, until we reach the great excess of Copper or the alloy 
Sn Cuio or Copper 84.68 and Tin 15.32 when the brittleness 
ceases, but strange to say this alloy which contains f ths 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 Cui6 or containing 88.97 of Copper. 
Sn Cu 2 0 5 5 5 5 91.49 ,, 
Sn Cu „5 „ „ 93.17 „ 
The authors also examined the degrees of hardness of Zinc 
and Tin, Tin and Lead, and Lead and Antimony alloys. 
Messrs. Calvert and Johnson also presented a paper “On 
the Specific Gravity of Alloys and Amalgams.” — They have 
arrived at the following interesting results, viz., that certain 
alloys and amalgams made of pure metals and in equivalent 
quantities, have a higher specific gravity than indicated by 
theory, whilst others have a loss specific gravity ; for example 
