Benchmark 10F
Historical Perspectives: Understanding Fire
Grades 6-8, page 250

Lavoisier's work was based on the idea that when materials react with each other many changes can take place but that in every case the total amount of matter afterward is the same as before. He successfully tested the concept of conservation of matter by conducting a series of experiments in which he carefully measured all the substances involved in burning, including the gases used and those given off.

See Content Standard G History and Nature of Science (grades 9-12): Historical Perspectives