Page:Biographies of Scientific Men.djvu/27

Rh the increased weight of iron after being heated in air was due to its absorption of something in the air: "Il est très possible que cette augmentation de poids soit venue de la matière répandue dans l'atmosphère." (See Voltaire's paper in Recueil des Pièces qui ont remporté les Prix de l'Académie royale des Sciences, Paris, 1752, tome iv., p. 171.)

Although Priestley first isolated "dephlogisticated air" or oxygen, it was left for the genius of Lavoisier to first interpret the phenomenon of combustion; and in 1778 (the year that witnessed the deaths of Voltaire and Rousseau within thirty-three days of each other) he established the fact that oxygen was the universal oxidizing principle.

During 1775 and subsequent years Lavoisier expounded his views on the nature of respiration, fermentation, and combustion; and we have to this day excellent sepia drawings by Madame Lavoisier of her husband's experiments on respired air.

In 1783 the composition of water was discovered by Cavendish, and confirmed the same year by Lavoisier and Laplace. Lavoisier was then able to explain the reactions which take place when metals dissolve in acids; and when metals burn to form calces, that oxygen is instrumental in the combustion. From the work of Cavendish, he first clearly stated the compound nature of water and determined accurately its volumetric composition (Kopp). "Although Cavendish was the first to show that water is