Liz Mr H. F. Newall, On the [Jan. 30, 
At the Ordinary Meeting which followed, Prof. StoKEs, Vice- 
President, in the Chair, the following communications were made: 
(1) On the Recalescence of Steel, and allied Phenomena. By 
H. F. Newatt, M.A., Trinity College. 
It is very striking how great are the differences in physical 
properties produced by minute differences in composition of 
specimens of iron and steel. The magnetic properties of iron 
are of such importance that it hardly needs pointing out that 
phenomena occurring nearly simultaneously with the birth of 
marked magnetic susceptibility are well worth studying. 
A piece of steel heated up to a white heat and allowed to cool 
shews, at certain points in the cooling, peculiarities recognized 
as occurring within a small range of temperature about red 
heat. 
It becomes brighter or reglows, instead of continuing to get 
gradually darker (Barrett, Phil. Mag., Vol. 46, 1873). 
It expands instead of continuing to contract (Gore, Proc. R. S. 
XVII., 1869). 
Tt becomes magnetic (Gilbert, Fox, Faraday and others). 
It shews changes in its thermo- electric relations (Tait, Trans. 
R. 8. Edin, Xxvit., 1873). 
Its electrical resistance changes (Smith, Knott and Macfarlane, 
Proc. R. 8S. Edin.). 
It ceases to be capable of assuming on sudden chilling the 
condition known as glass hardness (Chernoff, Strouhal and Barus). 
Its specific heat changes abruptly (Pionchon). 
Its rigidity shews marked peculiarities (Tomlinson, Newall, 
Phil. Mag. Xxi1v., 1887). 
Its viscosity shews marked changes. 
Many of these changes point to a change in the steel as marked 
as a chemical change would be. Some of the peculiarities are 
such as may be explained by a rise of temperature in the cooling 
steel. 
Recalescence or Reglow. 
The most striking way of shewing the darkening and re- 
calescence of steel is by heating a thin steel plate with a large 
blow-pipe flame. As heating proceeds, the plate becomes red hot : 
then a dark patch appears in the hottest part: this extends and 
opens into a dark ring, which expands, enclosing a constantly 
brightening patch. If the heating is now stopped, and cooling ~ 
allowed to take place, the luminosity of the whole hot part 
diminishes : there appears on the confines of the part lately occupied 
by the dark ring a bright ring, which contracts and becomes a 
