Geology and Natural History. 147 
2. Volumes of solid and liquid Cast Iron, with reference to 
the theories of Volcanic action.—Under the above title Mr. J. B. 
Hannay presents, in the Proceedings of the Philosophical Society 
of Glasgow for January, 1880, the results of experiments on cast 
iron. He first refers to the view of Messrs. Nasmyth and Car- 
penter, in their work on the Moon, that fusible substances, with 
few exceptions, are specifically heavier in their molten state than 
in the solid, and that, consequently, they expand on becoming 
solid, which view they sustain by referring to a fact recognized 
by iron founders, that a mass of solid cast iron dropped into 
molten iron of the same precise kind will float on it; and whence 
they draw the conclusions that solidification benéath the earth’s 
and depressions, over the surface. Mr. Hannay states that in his 
experiments, spheres of iron three to six inches in diameter were 
dropped into a bath of the same metal four feet wide and two 
ma 
course, as the sphere melted away. Another trial gave the same 
results, and the value was found to be constant. In other experi- 
ments the balls were fishe t wh eir maxi tempera- 
ture; and they showed, by the “tide-mark” left, the exact depth 
ubmergence, and also the relation between the volumes ensi- 
and *000065, giving a mean of -000060 per degree Centigrade. 
an account of experiments on the same point by Mr. Joseph 
Whitby and Mr. T. Wrightson. Mr. Wrightson’s earliest ex- 
periments are published in the British Association Report for 
1879, p. 506, ero results, from a much larger number of ex- 
periments on metals, are given in a paper in the “ Journal of the 
