274 Electric Conductivity of the Copper-Antimony Alloys. 



There is a very rapid fall from copper to the alloy containing 

 only 1 5 per cent, of antimony ; and this decrement is con- 

 tinued until the alloy SbCu 4 is reached, when the curve turns 

 rapidly and rises to SbCu 2 , and then turns again and passes 

 to pure antimony. It is not a little interesting that, in the 

 copper-tin series (Roberts), the alloy SnCu 4 occupies the 

 lowest part of the curve, precisely the position that, in the 

 copper-antimony series, is occupied by the alloy SbCu 4 . In 

 the copper-tin series, however, the second critical point is held 

 by the SnCu 3 ; and this point in the copper-antimony curve 

 is assumed, not by SbCu 3 , but by SbCu 2 . 



I may add that I have confirmed the composition of the 

 alloys at these critical points by analysis. 



SbCu 9 . SbCu 4 . 



t -*- * i : — * > 



Analysis. Theory. Analysis. Theory. 



Copper 50-85 50-5 68-38 68.1 



Antimony ... 49-15 49-5 31-62 _31 9 



100-00 100-0 100-00 100-0 



In determining the specific gravities, I find that they rise 

 gradually and evenly from antimony to the alloy Cu 4 Sb 

 (whose specific gravity is 8*871), and then diminish to the 

 specific gravity of copper. The " Regulus of Venus " has a 

 specific gravity 8*339, which does not in any way stand out 

 from the rest. 



Sh. Cu. Specific gravities. 



100 6-700 



95 5 



90 io !!!!!!!„!""!!!!■!!'!!! 7-005 



85 15 7-080 



80 20 7-306 



75 25 7-407 



70 30 7-615 



65 35 



60 40 7-995 



55 45 8-194 



50 50 (Cu 2 Sb) 8-339 



45 55 8-504 



40 60 8-617 



35 65 (Cu 4 Sb) 8-871 



30 70 8-823 



25 75 8-811 



20 80 8-802 



15 85 8-262 



10 90 8-637 



5 95 8-727 



100 8-85 



