42 
Names of Metals. 
Weight 
Employed. 
Calculated 
Cast lron=l,000. 
Cast Iron 
lbs. 
4,800 
1,000 
Steel 
Wrodght Iron 
4,550 
048 
Platinum 
1,800 
375 
Copper (pure) 
1,445 
301 
Aluminium 
1,.300 
271 
Silver (pure) 
Zinc ditto 
. 1,000 
208 
880 
183 
Gold ditto 
800 
1(17 
Cadmium ditto 
520 
108 
Bismuth ditto 
250 
53 
Tin ditto 
130 
27 
Lead ditto 
75 
1(1 
This table exhibits a curious fact, viz., the high degree of 
hardness of Cast Iron as compared with all other metals, and 
although we found alloys which possessed an extraordinary 
degree of hardness, still none were equal to Cast Iron. 
The first series of alloys which we shall give is that of 
Copper and Zinc. 
Formuloe of Alloys, and 
Percentages of each. 
W eight 
Employed. 
Obtained 
Cast lron=l,000. 
Calculated 
Cast lron=l,000. 
Zn 17.05 Cu, 82.95 ... 
lbs. 
2,1)50 
427.08 
280.83 
Zn 20.44 Cu^ 79.56 ... 
2,250 
468.75 
276.82 
Zn 25.52 Cug 74.48 ... 
2,350 
468.75 
276.04 
Zn 33.94 Cu^ 66.06 ... 
2,270 
472.92 
261.04 
Zn 50.68 Cu 49.32 ... 
2,900 
604.17 
243.33 
Cu 32.74 Zn^ 67.26 ... 
Breaks with l,500lbs., without the point entering. 
Cu 24.64 Zn, 75.36 ... 
Breaks with l,500lbs., with an 
impression ofl 
Cu 19.57 Zn^ 80.43 ... 
Enters a little 
i ]\r. M. deep, f 
more than the above. Breaks > 
Cu 16.30 Zn, 83.70 ... 
Enters 3 M. M. with l,500lbs. 
with2,000lbs. J 
Breaks with ) 
l,700lbs. i 
These results shew that all the alloys containing an excess 
of Copper are much harder than the metals composing them, 
and what is not less interesting, that the degree of hardness is 
due to Zinc, the softer metal of the two which compose these 
alloys. However the quantity of this metal must not exceed 
50 per cent, of the alloy, or the alloy becomes so brittle that 
it breaks as the steel point penetrates. We believe that some 
of these alloys with an excess of Zinc and which are not found 
