[Footnote 197: See the paper 'On Liquid Diffusion as applied to Analysis,' by the Master of the Mint (_Phil. Trans._ 1861, p. 222).] [Footnote 198: Compare the description of one of the hollow stalagmites I explored in the Schafloch, p. 145.] [Footnote 199: Professor Tyndall has pointed out that, owing to the want of perfect homogeneity, some parts of a block of ice exposed to a temperature of 32° F. will melt, while others remain solid _(Phil. Trans_. 1858, p. 214). He also arrived at the conclusion (p. 219) that heat could be conducted through the substance of a mass, and melt portions of the interior, without visible prejudice to the solidity of the other parts of the mass.] [Footnote 200: _Journal des Mines_, xxxiii. 157. See also an English translation of his account in the second volume of the _Edinburgh Journal of Science_.] [Footnote 201: It is to be hoped that the accuracy of his scientific descriptions exceeds that of his topographical information; for he states that the glacière is two leagues from Valence, whereas it cost me six hours' drive on a level road, and five and a half hours' walking and climbing, to reach it from that town.] [Footnote 202: Branch _Physique_, article _Glace_] [Footnote 203: P. 146 (an. 1853).] [Footnote 204: Dr. Lister experimented on sea-water in December 1684 (_Ph. Trans_, xiv. 836), and found that though it took two nights to freeze, it was much harder when once frozen than common ice, lasting for three-quarters of an hour under a heat which melted 100 times its bulk of common ice at once. It was marked with oblong squares, and had a salt taste. Ice formed from water with an admixture of sulphuric acid is said to assume a crystalline appearance.] [Footnote 205: See also a pamphlet entitled _Das unterirdische Eisfeld bei der Dornburg am Südlichen Fusse des Westerwaldes_, by Thomä of Wiesbaden (32 pages, with a map of the district), published in 1841.] [Footnote 206: But see page 262.] [Footnote 207: lv. (an 1842), 472.] [Footnote 208: _Journal de Physique_, xxvi. (an 1785), 34.] [Footnote 209: In looking through some early volumes of the _Philosophical Transactions_, I found an 'Extract of a letter written by Mr. Muraltus of Zurich (September 1668), concerning the Icy and Chrystallin Mountains of Helvetia, called the Gletscher, English'd out of Latin' (_Phil. Trans._ iv. 982), which at first looked something like an assertion of the prismatic structure of ice on a large scale. The English version is as follows:--'The snow melted by the heat of the summer, other snow being faln within a little while after, and hardened into ice, which by little and little in a long tract of time depurating itself turns into a stone, not yielding in hardness and clearness to chrystall. Such stones closely joyned and compacted together compose a whole mountain, and that a very firm one; though in summer-time the country-people have observed it to burst asunder with great cracking, thunder-like.']