62 Proceedings of the Eoyal Society of Edinburgh. 
Fig. 3a shows curves obtained with nickel and copper in successive 
heatings of a new specimen of nickel. Here the galvanometer indicated 
that the metals had started at about the same temperature,, but the copper 
cooling more quickly than the nickel, probably on account of its smaller 
specific heat, we get a difference of temperature established, which grows to 
a maximum just above A (most of the curves just begin to be recorded 
here, but Nos. 1 and 3 show part of this maximum), and thereafter the 
curves tend to get back to the temperature axis, except where they are 
interfered with by recalescences, the general trend of the curves being from 
right to left. These curves show two small humps, Iq and R 2 , occurring at 
the same temperatures, about 660° and 525° respectively, in all cases ; also a 
large hump occurring within the same temperature range in all cases, viz. 
440°-285°, being very evident as a change of slope at R, the original 
slope being regained at B. The large recalescence consists of two distinct 
parts, as at R 1 the slope again abruptly changes till the curve is nearly 
horizontal, indicating that heat is being given out at the greatest rate ther.e ; 
the first part, from R to R 1 , extends from 440°-370°, and the latter part, R 1 
to B, from 370°-285°. The general slope of the curves is seen above R x 
and again from B to C, while between R 1 and R 2 and between R 2 and R the 
curve has not regained this slope, showing a small and gradual evolution of 
heat here also. 
Fig. 3b shows the next two coolings taken of the same nickel and 
copper ; here the galvanometer indicated that the copper had started at a 
higher temperature than the nickel, and the general trend of the curve is 
therefore from left to right towards the temperature axis, which was crossed 
during the large recalescence, and when this is finished at B the curve turns 
back again towards the temperature axis. These curves again show the 
recalescences in same places, R 1? R 2 , and R to R 1 and B, though they have a 
less marked effect in changing the slope of the curve, owing to its general 
trend being from left to right. 
It may be noted here that the recalescence temperatures mentioned 
above cannot claim to be closer than to 5°, as I was only able to take readings 
of galvanometer deflection at intervals of 4J° or 5°. 
A large number of coolings were taken of the specimens, partly to 
gain experience in interpreting and partly to test the uniform occurrence 
of the recalescences, and the curves shown are a few typical specimens. 
Fig. 4 shows the effect of repeated heatings on the nickel ; these curves 
were taken after the specimen had been subjected to from fifty to sixty 
coolings. The effect is apparently that the temperatures at which the 
recalescences occur are unaltered, but R x at 660° is disappearing — it is just 
