ATOMS and MOLECULES

Greymouth Evening Star, 15 September 1924, Page 2

ATOMS and MOLECULES

WORKED OUT ARITHMETICALLY.

The fourteenth May lecture of the Institute of Metals was delivered on June 4 by Dr. F. W. Aston, F.R.S., in London (says “Engineering”). Dr. Aston said that nowadays all were aware that all matter was made up of discreet particles or atoms. There was an old Greek argument as to whether matter was infinitely divisible or whether further division would become impossible when a certain stage was reached. The Greeks never made experiments, and could therefore argue such as this at any length. Modern science had, however, been able to decide the matter in favour of the second hypothesis, and an idea as to the extreme minuteness of the ultimate particles could be obtained by considering successive divisions of a cube of lead. Starting with such a cube ; of one em. edge, this could be divided into eight equal cubes by .sections through the midpoint. Repeating the operation on one of these small cubes, the result was cubes of l-64th the volume of that from which the experiment started. Proceeding in this to successive divisions of the same kind, the volume diminished with extreme rapidity. With the ninth repetition we got the smallest mass recognisable by ordinary chemical methods. The quartz fibre micro-balance, which could weigh one-millionth of a milligram, became ineffective beyond the fourteenth operation. Spectrum analysis failed beyond the fifteenth, whilst the micros* cope could not recognise particle smaller than those resulting from the eighteenth repetition, but the ultimate atoms would not be reached until the twenty-eighth operation. ' If all the lead atoms in the original cube of 1 em. side were striing out into.a chain this would be Six million million miles long.' ' ■ ’

As another illustration of this minuteness of the. molecule, if a very small

hole were pierced in an electric light bulb, admitting air into the evacuated space at the rate of 1,000,000 molecules a second, the pressure inside would not reach that of the atmosphere till the lapse of 100,000,000 years. Again, suppose it' were possible to “ear-mark” the idividual molecules of a tumbler of water, which was then poured into the sea. After a few million years this water would be thoroughly mixed up with the rest of the water on the earth. If then, after this thorough mixture, another tumbler of water were drawn anywhere on earth it would contain 2000 of the original “earmarked” molecules. In fact, there were 2000 times as many molecules' in a tumbler of water as there were tumblers of water in all the oceans of the earth.