86 ROYAL SOCIETY OF CANADA 



DisciLssion. — From the values recorded in Table III it will be Been 

 that the specific resistance of alloys No. 2 and No. 2 A were excep- 

 tionally high, and although with the two alloys the resistances were 

 determined for only a limited number of points it is evident from the 

 form of the curves that the specific resistance of both underwent wide 

 and irregular though somewhat similar variations. The existence of 

 a maximum and a minimum value for the specific resistance of each 

 in the range covered appears to be clearly established, and it is probable 

 that had measurements for a larger nimiber of temperatures been made 

 these critical values would have been still further emphasized and more 

 definitely determined. 



Alloys Nos. 3. 3A and 3B, as well as Nos. 4 and 4A, shew very 

 nearly a linear relation between specific resistances and temperatures, 

 and in their behaviour approximate more closely to that of pure metals. 



A comparison of the values of the specific resistance of these alloys 

 with the known values of their constituents Cu. and Al. (that for Mn, 

 apparently has not yet been determined) shews that all the specimens 

 had a higher specific resistance than either of these two constituents. 

 In this respect then the Heusler alloys resemble various alloys examined 

 by Fleming and Dewar, and others. But, in the determinations of 

 the latter the difference observed between the specific .resistances of 

 particular alloys and that of their respective components were not so 

 large as that exhibited, for example by alloys 2, 2A. 



This fact, coupled with the pronounced change in specific resistance 

 which has been found to follow variations in the percentage composi- 

 tion of these alloys, make it desirable to have a more complete aeries 

 of determinations for a larger number of specimens, and it is possible 

 when these are made, that some additional information will be obtained 

 which will assist in establishing a relation between the various phases 

 of these alloys and the physical properties which they manifest. 



It gives the writers pleasure to express, in this place, their sincere 

 thanks to Prof. McLennan for his kindness in placing at their disposal 

 the necessary apparatus to carry out the experimental work, and for 

 his many helpful suggestions given from time to time during the 

 investigation. 



