John Dalton proposed his law of partial pressures for gases in 1801. In 1803 he put forth his atomic theory, which described matter as being composed of tiny discrete particles that he called atoms. Dalton's atomic theory explained the law of conservation of matter (Lavoisier), the law of definite proportions (Proust's Law), and allowed him to predict the third law of combination (multiple proportions). Despite this, atomism wasn't accepted by the entire scientific community for almost 100 years. Passionate about his theory, Dalton's death in 1844 was apparently from a sudden apoplexy following a violent argument defending his atoms.