1908-9.] On the Recalescence Temperatures of Nickel. 
57 
III. — On the Recalescence Temperatures of Nickel. By T. A. 
Lindsay, M.A., B.Sc., Carnegie Scholar, Edinburgh University. 
Communicated by Professor J. G. MacGregor. 
(Read July 20, 1908. MS. received September 25, 1908.) 
The object of the experiments described in this paper was to study 
the cooling of nickel, and to endeavour to get recorded any recalescence 
which might occur. A specimen of pure nickel could not be obtained, 
but the nickel worked with, supplied by Messrs Johnston & Sons, con- 
tained less than 2 per cent, of impurities. 
The critical ranges of nickel, or the temperature ranges over which 
changes in certain of the physical properties of nickel occur, have for 
long been a subject of investigation, and various workers have attempted 
to get evidence of evolution of heat or “ recalescence ” at these temperatures, 
but no successful attempt seems to be on record. Take,* reviewing the 
work done in this direction, says : “ It may be stated that neither anomalous 
changes of length nor recalescence phenomena have been observed in the 
case of nickel.” 
In the most recent work on the recalescence of metals the “ differential ” 
method introduced by Roberts- Austen has been adopted, and Rosenhain,j- 
in a discussion of the various methods of taking cooling curves, indicates 
that this “ differential ” method is the best. In my preliminary experi- 
ments I used the Roberts- Austen arrangement, but abandoned it for the 
simpler modification used by Carpenter and Keeling J in their work on iron- 
carbon alloys, as I found the latter gave more readily interpretable results. 
In the method as used by Carpenter and Keeling, blocks of the metal 
under observation and of a metal which cools regularly without recalesence 
are placed close together in a furnace ; thermo-electric junctions of the 
same kind of wires are inserted in the metal blocks, and so connected to a 
galvanometer that when heated they send current through the galvano- 
meter in opposite directions, and in this way the galvanometer indicates 
any difference of temperature between the two metals ; another thermo- 
couple inserted in the metal under observation is connected to another 
* Magnetische Untersuchungen, Biss. Marburg , 1904, p. 88. 
t Physical Society of London, Jan. 24, 1908. 
X Journal Iron and Steel Institute , 1904, vol. i. p. 224. 
