61 
1908-9.] On the Recalescence Temperatures of Nickel. 
will be a more or less pronounced but small hump on the curve ; but if it be 
of large range, the result will be either a large hump or a long-drawn-out 
and flat hump, according to the rate of evolution of heat. Under actual 
conditions these humps may not be readily recognised, being concealed by 
the sinuosities of the curve due to errors of observation ; but as these 
sinuosities differ from experiment to experiment, while the recalescence 
humps preserve their position, except in so far as it may be altered by 
repeated heatings, it is quite possible to recognise a recalescence hump even 
of comparatively small size, by comparing with one another a series of 
cooling curves. 
Fig. 2 shows typical specimens of curves with no recalescence humps ; 
they are taken with two pieces of copper of different size, and are approxi- 
mately straight lines, except for the slight sinuosities, which give an idea of 
the limits of size within which humps could not be interpreted as recales- 
cences. In these cases the galvanometer indicated a difference of temperature 
between the two pieces of metal initially, and the curve is constantly running 
down towards the temperature axis so far as it is recorded. 
