205 



December 22, 1859. 



Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 

 Bennet Woodcroft, Esq., was admitted into the Society. 

 The following communications were read : 



I. "On the Electric Conducting Power of Alloys." By A. 

 MATTHIESSEN, Pn.D. Communicated by Prof. WHEAT- 

 STONE. Received November 17, 1859. 



(Abstract.) 



In this paper I have given the determinations of the electric con- 

 ducting power of upwards of 200 alloys, and have found that the 

 metals employed may be divided into two classes, viz. 



A. Those metals which, when alloyed with each other, conduct 

 electricity in the ratio of their relative volumes. 



B. Those metals which, when alloyed with one of class A, or with 

 each other, do not conduct electricity in the ratio of their relative 

 volumes, but always less. 



The alloys may be divided into three groups ; viz. 



1 . Those made of the metals of class A with each other. 



2. Those made of the metals of class A with those of class B. 



3. Those made of the metals of class B with each other. 



From the experiments described in the paper I have tried to deduce 

 the nature of alloys, and have arrived at the following conclusions : 



A. That most alloys are only a solution of one metal in the other ; 

 for, 



1. On looking at the curves belonging to the different groups, we 

 see that each group of alloys has a curve of a distinct and separate form. 

 Thus for the first we have nearly straight lines ; for the second, the 

 conducting power decreases always rapidly on the side of the metal 

 belonging to class B, arid then turning, goes almost in a straight 

 line to the metal belonging to class A j for the third group we find a 

 rapid decrement on both sides of the curve, and the turning-points 

 united by almost a straight line. 



