64 Proceedings of the Royal Society of Edinburgh, [Sess. 
evident as a slight bulge in the curve— and that at 525° is getting smaller 
in size also, while the gradual evolution of heat from R x to R 2 seems also 
to have disappeared, though this is not quite certain. These results are 
corroborated in fig. 5, these curves being also taken at about the same time. 
In the case of fig. 4 curves, the metals had started about the same tempera- 
ture and attained maximum difference of temperature just above A, and there- 
after tended towards the temperature axis just as the curves in fig. 3a did. 
Rosenhain * has found that recalescence occurs in silica porcelain at 
about 550°, and as this is present in some furnaces, it gives rise to mislead- 
ing results. No such indication of recalescence is given in my curves of 
copper and copper in fig. 2 ; but to find whether or not my results were 
due to recalescence of the materials of the furnace used, I took coolings in 
a fireclay gas muffle, packing the specimens in loosely with asbestos. The 
curves got are shown in fig. 5, and are in agreement with the other curves 
in their recalescence indications ; it will be noticed that curves 1 and 2 
have the humps smaller, but this is due to the galvanometer being shunted 
* Physical Society of London, January 24, 1908. 
