201 



On submitting both alloys to analysis, their constitution 

 proved identical ; it is as follows : 



Copper 83.523 



Tin 8.833 



Zinc 7.510 



Lead 0.024 



Loss 0.110 



100.000 

 Uniting the small amount of lead with the tin, and dividing 

 by the atomic weights, the nearest approach to atomic con- 

 stitution is, 



Copper = 26.3 atoms. 



Zinc = 2.3 



Tin = 1.5 



These alloys have therefore not a strictly definite constitution, 

 but one more nearly so than is usually found in commerce. 



Both alloys are equally good conductors of electricity. 

 The author examined their relative powers of conducting heat 

 by the method which Despretz has employed with so much 

 accuracy, and found that of the normal to that of the anoma- 

 lous alloy as 36 : 35, numbers which are so nearly equal as 

 to render it likely the difference is only error of experiment. 

 He also endeavoured to determine their relative specific 

 heats, using the method of mixture, which was the only one 

 which the small size of the metals permitted, and eliminating 

 the errors incident to this mode by first plunging the alloy 

 hot into cold water, and then cold into hot water. In this 

 way, if 



w and t = the weight and temperature of the water, 

 M and t' = the weight and temperature of the metallic alloy, 

 m. . . . = the mean temperature of both, 

 s . . . . = the specific heat of the alloy, 

 there are two values, one where the metal is the hotter, 



