If you designed your own experiment to prove the law of conservation of matter, what conditions would be required?

If you designed your own experiment to prove the law of conservation of matter what conditions would be required class=
If you designed your own experiment to prove the law of conservation of matter what conditions would be required class=
If you designed your own experiment to prove the law of conservation of matter what conditions would be required class=
If you designed your own experiment to prove the law of conservation of matter what conditions would be required class=