1. What are the laws of organic chemistry? 2. When was the law of preservation of weight of substances first formulated? 3. Who formulated the law? 4. In what year was the law experimentally proven? 5. What is the modern formulation of this law? 6. Which French chemist also formulated the law in 1789? 7. How did he gather his proofs of the law? 8. What has originated from Lomonosov's works? 9. Who developed the periodic law? 10. How can the law of preservation of weight of substances be explained from the nuclear-molecular doctrine's point of view? Annotation: The article is headlined "The Law of Preservation of Weight of Substances" and it was written by Stanley K. Brubaker. It was published in the Nature Friends on 5th July 2003. As the title implies, the purpose of the article is to give the reader some information on one of the main laws of organic chemistry, which states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformation. The author also mentions two independent scientists who formulated the the law of preservation of weight of substances in the 18th century. The article also briefly states how the new chemistry is influenced by this law. I found the article very fascinating and informative but hard to understand at first. I would recommend to read this article to people who are interested in chemistry.