424 
Proceedings of the Royal Society 
appearance without any marked peculiarity, but the Pd-Co curve, 
though parabolic at comparatively low temperatures, showed at the 
higher temperatures an apparent tendency to straighten, thus 
indicating a possible point of contrary-flexure, i.e., a bend in the 
cobalt line at a temperature somewhere about or above a bright red 
heat. The approximate position of the cobalt line may be gathered 
from these facts : that the line of 15° C is divided by the points of 
intersection of the cohalt, palladium and M lines in the ratio of 
11 : 8 , and that the cobalt line is inclined to the horizontal at an 
angle not quite double of the angle of inclination of palladium. 
In experiments made to-day with a double circuit of Co-Pd 
against nickel, with some resistance thrown into the cobalt arm, a 
neutral point has been got at a temperature of about 500° F. This 
shows us that by the aid of cobalt we shall be able to investigate the 
peculiarities of nickel more accurately, while from the parts of the 
nickel line which are already known we shall be able to fix definitely 
the position of the cobalt. It is worthy of notice that even at the 
high temperatures of the red-hot or even white-hot cylinder the 
cobalt shows no tendency to oxidise. 
Electric Conductivity . — During the last few days we have been 
carrying on a scries of experiments on the change of the electric 
conductivity of cobalt with change of temperature. For this we 
prepared a very narrow strip of cobalt by depositing it on the edge 
of a piece of aluminium. To the ends of the strip so prepared 
stout copper wires were soldered, and the experiments were then 
carried on as in the case of nickel (Proc. Roy. Soc. Edin., 1875-6, 
p, 120). The line obtained was not straight but slightly curved, 
showing apparently a gradual alteration in the rate of change of 
conductivity. Within the temperature of boiling oil, however, 
there is no indication of a sudden change, and the curve in the 
line may be due to several disturbing causes which we have not as 
yet been able to eliminate. 
