Conservation of Matter


Boyle's discovery of the behavior of gas particles led other chemists to experiment with solid particles. By the end of the 1700's almost 30 different elements had been discovered. Most of the common metals, such as copper, silver, iron, and tin, are elements. These elements were already known to the ancients, but the chemists of the 1700s also found new metal elements, such as nickel, cobalt, and uranium. These chemists also discovered elemental gases, such as nitrogen and oxygen, and elemental non-metals, such as carbon, sulfur, and phosphorus. For a few chemists, this raised the question whether every element has a different kind of atom or not. Most chemists, however, ignored anything too small to be seen, and concentrated their efforts on finding new elements.
Ironically, it was one of the chemists who wasn't interested in atomism who helped prove it. His name was Antoine Laurent Lavoisier, a French chemist during the late 1700's. Lavoisier spent most of his time working as a tax accountant for the French government, but he devoted his free time - an hour or two each morning and one day off each week - to studying science. His particular area of study was combustion. Lavoisier, along with his wife Marie Anne, built an elaborate apparatus in which he placed rusting metal (Bodanis 30). After applying heat to speed up the rusting, he would allow the metal to cool, and then he weighed it. Much to his surprise, the rusted sample always weighed more than it did before. After carefully measuring the air in his self-contained apparatus, he realized that the added mass had come from the air. This meant that although substances can be changed through chemical reactions, like rusting, the total mass of the system can't change. Through his careful measurements, Lavoisier had discovered the law of conservation of matter.

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