In the fifth century B.C. Indian philosopher Maharshi Kanad postulated that if one goes on dividing matter (Padarth), he would get smaller and smaller particles and a limit will come when he will come across smallest particles beyond which further division will not be possible. He (Kanad) named the particles Parmanu. More or less during the same period Greek philosophers, Leuappus and Democritus suggested similar ideas. This idea was not accepted at that time but it remained alive. Not much experimental work could be done until Lavoisier gave his law: Law of conservation of mass and law of constant proportions sometimes in 1789. English scientist and school teacher, John Dalton (1766-1844) provided the basic theory about the nature of matter: All matter whether element, compound or mixture is composed of small particles called atoms.