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The history of chemistry includes the development of quantitative methods for identifying substances and explaining chemical change. A decisive experimental advance was accounting for gases as material participants: a solid can gain mass during heating while the corresponding enclosed gas loses material to it.

Work on different kinds of air, combustion, and chemical composition helped replace a single undifferentiated view of air with experimentally distinguishable gases. Lavoisier's account of mercury and air records a closed-system interpretation in which only part of the air is consumed, connecting chemical explanation to measured material balance.^[ref]