and Kelvin came to the conclusion that the distance between the centres of contiguous molecules is less than the one-five-millionth and greater than one-thousand-millionth of a centimetre.
All this work has been the outcome of Dalton's atomic theory. Sir George Darwin says that "within the last few years the electrical researches of Lenard, Röntgen, Becquerel, the Curies, Larmor, Thomson, and a host of others have shown that the atom is not indivisible (as Dalton assumed), and a flood of light has been thrown thereby on the ultimate constitution of matter. Among all these fertile investigators it seems that J. J. Thomson stands pre-eminent, because it is practically through him that we are to-day in a better position for picturing the structure of an atom than was ever the case before. It has been shown that the atom really consists of large numbers of component parts. By various converging lines of experiment it has been proved that the simplest of all atoms, namely, hydrogen consists of about three hundred separate parts; while the number of parts in the atom of the denser metals must be counted by tens of thousands. These separate parts of the atom have been called corpuscles or electrons, and may be described as particles of negative electricity."
As Professor Rutherford says: "It is not true that the discoveries of the last ten years had weakened the atomic theory. On the contrary, they had enormously strength-
