555 
of Edinburgh , Session 1881-82. 
(8) With, the view of ascertaining the rate of increase due to rise of 
temperature, some experiments were made by heating pieces of test- 
bars in a smith’s fire, and noting the extension according to the 
time. 
These experiments pointed out that the increase of size is at 
first rapid, and thereafter comparatively slow ; thus a piece of test- 
bar, 2 in. x 1 in. x 13 in., had two centre points marked upon it 
exactly 1 2 inches apart ; it was placed in a smith’s fire and heated 
for about a minute, when it was found to have gained about 
T \- of an inch ; would not melt lead. Again heated for about same 
time, and found to have about of an inch of an increase ; still 
black, and did not melt lead ; heated again, and now found to have 
its original length increased by J of an inch, it was now a dull red 
and melted lead, heated once more for two minutes, and now a 
bright red ; but the increase, very little if any over the J of an inch ; 
heated again, and taken out white hot, when it broke in two pieces. 
Another piece, same size, was tried by heating it up to a white heat 
at once, time about four minutes. The expansion was nearly fr of 
an inch ; put in fire again, and taken out very white hot showed 
about T 3 g- of an inch of increase in the 12 inches. Allowed to cool 
gradually, and in seven minutes it measured 1 2 J inches ; it was 
now quite dark, and melted lead when the latter was rubbed on 
the bar. 
These experiments quite corroborate the floating metal ex- 
periments so far as the rate of increase in size goes, viz., that 
at first, and even at a comparatively low temperature, there is a 
large increase, and that thereafter the increase is much less in 
proportion to the greatly increased temperature even at white 
heat. 
The author, therefore, thinks that both experiments prove that a 
large part of the first applied heat disappears in work of extension, 
the later applied heat showing more distinctly rise of temperature 
and change of condition of the metal towards melting. 
(9) Some experiments were carried out to determine the question 
of expansion of cast iron on setting; the results of these are, 
however, not favourable to such an action, as no special movement 
could be detected. And, indeed, all the practical men whom the 
author has consulted, agree in stating that they have not observed 
