^{page 296 note 2} See Geol. Mag. 12 III. Vol. VII. pp. 562–564.Google Scholar

^{page 296 note 3} See the letters of MrFisher, and MrBarker, in the GEOLOGICAL MAGAZINE for January, 1891.Google Scholar

^{page 297 note 1} Those who wish for real information on the subject may be referred to Pattison, Muir's “Thermal Chemistry” (1885), and the English edition of Ostwald's “Outlines of General Chemistry” (1890), both published by Macmillan.

^{page 297 note 2} See Chemical News, Nos. 1402 and 1505, “On Dissociation and Contact Action.”

^{page 298 note 1} For a clear exposition of these principles see a paper by Pickering, Spencer U., F.R.S., on “Chemical Action and the Conservation of Energy,” Nature, vol. xliii. pp. 165–167.Google Scholar

^{page 298 note 2} Very well illustrated in the case of ammonia, which will burn continuously in pure oxygen, but not in common air.

^{page 298 note 3} See my “Chem. and Phys. Studies, etc.” p. 54.Google Scholar

^{page 299 note 1} Since writing this paper I have noticed that the above cases with some others are discussed in a very suggestive (though scarcely exhaustive) manner by Professor Liveing in his little book “Chemical Equilibrium, the Result of Dissipation of Energy” (1885).

^{page 299 note 2} Referring to the geometrical construction used by Mr. Fisher (loc. cit.).

^{page 300 note 1} An illustration will perhaps make this clear. We may expend a definite amount of energy furnished either by the muscles of a horse or the fuel consumed in the fireplace of an engine in drawing a series of loaded trucks along a perfectly horizontal line of rails. Work is done in overcoming the friction of the wheels against their axles and against the rails, and in the displacement of a portion of the atmosphere with the movement of the train; but would any one contend that energy was stored up in the train?

^{page 301 note 1} See Allgem. und Chem. Geol. pp. 308–310:Google Scholar “Es geht also aus diesen Versuchen ganz entschieden hervor, dass starker Druck die chemische Verwandtschaft dann aufhebt, wenn zu der Entfaltung ihrer Wirksamkeit eine Volumvermehrung esforderlich ist.”

^{page 301 note 2} Brit. Assoc. Report, Aberdeen Meeting (1885), p. 846.Google Scholar

^{page 302 note 1} This was pointed out by me in App. ii. note D of my original thesis written in 1887 (see “Chem. and Phys. Studies,” etc., p. 108).Google Scholar

^{page 302 note 2} See “Am. Journ. Sci.” vol. xxxv. (1888) p. 78,Google Scholar and vol. xxxvi. (1888) p. 285, et seq. I am much obliged to General MacMahon for furnishing me with these references.

^{page 302 note 3} See “Zeitschrift für physik. Chemie,“ i. 5, cited in ‘Nature,’ vol. xxxvi. p. 160.Google Scholar

^{page 302 note 4} Wislicenus, , “Organische Chemie,” pp. 541, 642.Google Scholar

^{page 302 note 5} From certain known facts, it does not seem at all improbable that such complex syntheses may have taken place extensively in the early stages of the genesis of rock-forming minerals. Among them I have suggested (“Chem. and Phys. Studies,” etc., App. ii. note Q) the formation of minerals of the spinel type, in which Al₂O₃ plays the part of an acid, the alumina being set free with subsequent alteration of physical conditions, to enter into new relations as a base.

^{page 303 note 1} With one exception, which no one has noticed. When I said ‘shear-planes’ I should have said ‘shear- and thrust-planes.’

^{page 303 note 2} Compare pp. 10–15 of my “Chem. and Phys. Studies in the Metamorphism of Rocks”; also the quotation from Pfaff in App. ii. Note K. The work of pfaff is not as well known as it should be by English geologist.