(1) Balancing is required by the law of conservation of matter.

(2) Conservation of matter and energy in the universe.

(3) The law of conservation of matter keeps all the material exist after thousands years.

(4) For Lavoisier the crucial principle behind chemistry had been the conservation of matter.

(5) But as for the problem whether "soul" exists, it will be easier to explain it by the Li Law of the Conservation of Matter and Reason.

(6) A material balance is based on the law of conservation of matter.