In chemistry, conservation of mass, one of the conservation laws, states that in a chemical reaction or process the mass of the compoments of atoms in the reactants will equal that of the products.

History
The first to clearly announce the law of conservation of mass, according to Gilbert Lewis (1925), was French physician-chemist Jean Rey, who in his 1630 The Increase in Weight of Tin and Lead on Calcination stated the following: [1]

“Let there be taken a portion of earth which shall have in it the smallest possible weight, beyond which no weight can subsist: let this earth be converted into water by means known and practiced by nature; it is evident that this water will have weight, since all water must have it, and this weight will either be greater than that of the earth, or less than it, or else equal to it. My opponents will not say that it is greater, for they profess the contrary, and I also am of their opinion: smaller it cannot be, since we too the smallest weight that can exist: there remains then only the case that the two are equal, which I undertook to prove.”

French thinker Emilie Chatelet (1706-1749) performed what would eventually come to be known as Lavoisier’s rust experiment (1774), at a time at which it is said that if her scales were more accurate, she would have arrived at the law of conservation of mass.

The first to enunciate the conservation of mass, according to Leon Winiarski (1898), however, was French chemist Antoine Lavoisier. [2] Lavoisier, in circa 1789, supposedly, confirmed many of Rey's hypotheses by more exact experiment.

References
1. Lewis, Gilbert N. (1925). The Anatomy of Science (pg. 91), Silliman Lectures; Yale University Press, 1926.
2. Winiarski, Leon. (1898). “Theory of Property and Family: Essay on Social Mechanics” (Italian → English) ("La Teoria Della Proprieta E Della Famiclia: Saggi Sulla Meccanica Sociale Pura") (pgs. 572-594) In: Rivista Italiana di Sociologia (Italian Journal of Sociology), Volume 3. Fratelli Bocca, 1899.

External links
‚óŹ Conservation of mass – Wikipedia.

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