In all of the physics books I have, the story is Millikan, in measuring (calculating) the charge found on tiny oil drops, "found them all to be integer multiples of a single, fundamental unit", the electron charge -e. The question I have is, HOW did he show them to all be multiples of a fundamental unit - that is, how did he show charge to be quantized? I can dream up some very "soft" ways of "showing" this - IE, dividing each calculated charge by the smallest difference between charges, and then playing around with this smallest difference value until each charge divided by the value is very close to an integer, perhaps doing a least squares type of fitting. But there must be a more formal way to show that, given a (large) set of data, each element in the set is essentially an integer multiple of some constant, and then determining that constant. This would be related to the neat little experiment I've seen a few places in physics education literature, where the oil drop experiment is simulated with a bunch of envelopes each containing random numbers of identical ball bearings. The idea is to measure the mass of each of the many envelopes, and then to determine the mass of a single ball bearing, analagous to the fundamental charge of the electron. In this case, I imagine dividing all the differences between bags of similar mass by the smallest difference between two bags, and trying once again to get integer values. But this would only work if the difference in mass between two of the bags was just one ball bearing, which may not be the case. Any suggestions or revelations would be greatly appreciated. I'm stumped. Thanks.