grainy and that everything was made up of large numbers of various different kinds of atoms. (The word atom means ΓÇ£indivisibleΓÇ¥ in Greek.) For centuries the argument continued without any real evidence on either side, but in 1803 the British chemist and physicist, John Dalton, pointed out that the fact that chemical compounds always combined in certain proportions could be explained by the grouping together of atoms to form units called molecules. However, the argument between the two schools of thought was not finally settled in favor of the atomists until the early years of this century. One of the important pieces of physical evidence was provided by Einstein. In a paper written in 1905, a few weeks before the famous paper on special relativity, Einstein pointed out that what was called Brownian motionΓÇöthe irregular, random motion of small particles of dust
