484 Increase of Electrical Resistivity caused ~by Alloying Iron. 



atomic weight produce the least increase in electric resistivity and vice 

 versd. For the sake of such a comparison, the molecular weights of 

 these elements, if we knew them, rather than the atomic weights, 

 should be taken. This is especially true in the case of carbon, the 

 molecular weight of which, if this analogy holds good, would appear to 

 be four times its atomic weight. If, instead of the atomic weights, we 

 take the specific heats of these elements, so far as they are known, we 

 ure likely to arrive at a better knowledge of their relative atomic or 

 molecular masses, and a comparison of the order of specific heats with 

 the order of increase of electric resistivity is very striking. This is 

 shown in the next table.* 



Dividing the increase in electric resistivity by the percentage of the 

 added metal, we obtain the increase in the specific resistance of iron 

 produced by 1 per cent, of the added element. This is shown for a 

 2 per cent, alloy (except in the case of carbon) in the second column 

 of Table II, along with the specific heats and atomic weights of the 

 elements named in the first column. 



Table II. 



I venture to think that the correspondence shown in columns 2 and 

 3 of the foregoing table is something more than a chance coincidence. 

 It is, however, desirable to have exact determinations of the resistivity 

 of a larger number of alloys of iron before any definite conclusions 

 can be reached. 



A series of experiments are in progress for the measurement of the 

 relative thermal conductivity of the foregoing alloys. About forty 

 determinations have been made, and so far the order of thermal 



* The values for the specific heats are taken from Landolt and Bernstein's great 

 work on Physical Constants. The specific heat determinations are chiefly by 

 Reguault, between 9 and 97 C. 



t For a 1 per cent, alloy. 



J As graphite; as diamond the specific heat of carbon is O'llS, according to 

 H. F. Weber. 



