CHAPTER II

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THE LAWS OF CHANGES OCCASIONED BY HEAT.

_Sect._ 1.--_Expansion by Heat.--The Law of Dalton and Gay-Lussac for Gases._

ALMOST all bodies expand by heat; solids, as metals, in a small degree; fluids, as water, oil, alcohol, mercury, in a greater degree. This was one of the facts first examined by those who studied the nature of heat, because this property was used for the measure of heat. In the _Philosophy of the Inductive Sciences_, Book iv., Chap. iv., I have stated that secondary qualities, such as Heat, must be measured by their effects: and in Sect. 4 of that

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