As a scientist, Lomonosov was equal parts thinker and experimenter. He tested his theories and hypotheses with experiments that he planned and carried out himself. Although proficient in math, he never used differential calculus. He would work on research topics for years, even decades at a time, always with an eye toward turning discoveries into new practices or inventions.
Lomonosov believed physical and chemical phenomena were best explained in terms of the mechanical interactions of corpuscles—“minute, insensible particles” analogous to what we now know as molecules.1 Giving name to the philosophy, he coined the term “physical chemistry” in 1752.
He is perhaps best known for being the first person to experimentally confirm the law of conservation of matter. That metals gain weight when heated—now a well-known consequence of oxidation—confounded British chemist Robert Boyle, who had famously observed the effect in 1673. The result seemed to implicate that heat itself was a kind of matter. In 1756 Lomonosov disproved that notion by demonstrating that when lead plates are heated inside an airtight vessel, the collective weight of the vessel and its contents stays constant. In a subsequent letter to Euler, he framed the result in terms of a broad philosophy of conservation:
All changes that we encounter in nature proceed so that . . . however much matter is added to any body, as much is taken away from another . . . since this is the general law of nature, it is also found in the rules of motion: a body loses as much motion as it gives to another body.