of MM. P. Curie and C. Cheneveau. 367 



in progress in the laboratory, circumstances compelled us to 

 use brass conductors, and the results obtained were higher 

 than those given by calculations based on theory. This could 

 only be accounted for by assuming a permeability for the 

 brass greater than unity, and although the magnetism in the 

 metal Avas not detectable by a fairly sensitive magnetometer, 

 it was readily shown when samples of the conductors were 

 tested in the balance. 



Nine samples of copper are tabulated, and one only is 

 diamagnetic, again emphasizing the difficulty of obtaining 

 really non-magnetic conductors. 



The tin sample was chemically pure and is also magnetic. 

 Of the three samples of zinc the first two are ordinary com- 

 mercial sheet metal, and the third one is a rod of chemically 

 pure metal for use in standard cells. 



The next portion of the table is devoted to an examination 

 of the series of resistance alloys, whose electrical properties 

 were investigated by the writer some time ago and published 

 by Dr. Drysdale in connexion with his paper upon the 

 Comparison of Standard Resistances, before the British 

 Association at Leicester, 1 907. 



The first point which strikes one in connexion with these 

 is the fact that every alloy is magnetic, but that those alloys 

 containing relatively a large proportion of the magnetic 

 metal nickel, i, e. Nickelines, are among the least so. The 

 first sample is very different from the other three, and we 

 have reason to believe that the second and fourth samples are 

 of the same manufacture although obtained from different 

 firms. 



The samples of Platinoid fall into this group with properties 

 very comparable with the Nickelines, and the material sold 

 under the trade name of Extra Prima probably also belongs 

 to this group. 



The Constantans come next in order, being more magnetic 

 than the Nickelines, and it is not difficult to see that the 

 material catalogued as 1A1A belongs to this group of alloys, 

 together with the alloy supplied to us under the title of New 

 Metal, while the sample German Silver 2a, but for its high 

 density and positive temperature coefficient, would also be 

 classed among the Constantans. 



Eureka is a resistance material which is often classed as a 

 Constantan, but the balance easily disproves this, as it shows 

 it to be so magnetic that observations would have had to be 

 made with a stiffer suspension than we were using, and this, 

 coupled with its positive temperature-coefficient, rule it out of 

 the group. 



