FOOTNOTES:

[25] See Buchanan on the Economy of Fuel and Management of Heat, especially as it relates to heating and drying by means of Steam.

[26] See Brewster's Edinburgh Encyclopædia, article Steam-drying Machine.

[27] The following are the words in which Watt makes this remarkable announcement to Priestley:—

"Let us now consider what obviously happens in the deflagration of the inflammable (hydrogen) and dephlogisticated air (oxygen). These two kinds of air unite with violence; they become red hot, and upon cooling, totally disappear. When the vessel is cooled, a quantity of water is found in it equal to the weight of the air employed. This water is then the only remaining product of the process; and water, light, and heat are all the products.

"Are we not then authorised to conclude, that water is composed of dephlogisticated air (oxygen) and phlogiston (hydrogen), deprived of part of their latent or elementary heat; that dephlogisticated or pure air (oxygen) is composed of water deprived of its phlogiston (hydrogen), and united to elementary heat and light; and that the latter are contained in it in a latent state, so as not to be sensible to the thermometer or to the eye; and if light be only a modification of heat, or a circumstance attending it, or a component part of the inflammable air (hydrogen), then pure or dephlogisticated air (oxygen) is composed of water deprived of its phlogiston (hydrogen), and united to elementary heat."

[28] Those who desire to investigate this controversy more in detail will find very full information on the subject in the Translation of Arago's Eloge, with notes and appendix by J. P. Muirhead, Esq. Murray, London, 1839.

[29] An account of this remarkable apparatus, accompanied by an engraving made from a drawing supplied by Watt, was communicated by Sir John Robison to the Edinburgh Philosophical Journal in 1820. See vol. iii, p. 60.