"HEAVY WATER"

Press, Volume LXXI, Issue 21386, 31 January 1935, Page 8

"HEAVY WATER"

VALUE OF RECENT EXPERIMENTS VIEWS OF DR. C. C. FARR The nature of "heavy water," which was drunk recently without harmful effects by Professor Klaus Hansen, of Norway, was explained by Dr. C. Coleridge Farr, of Canterbury College, in an interview yesterday. He said that ordinary water is, in fact, a mixture of the "light" and "heavy" varieties, though the latter occurs only to the extent of about one-part in 6000. To understand the difference in the two kinds of water it is necessary to bear in mind that there are 92 elementary substances, of which all others are chemi.cal compounds. Each atom of any of these elements has a certain nuclear charge of electricity, and this is the controlling factor which determines the behaviour and character of the atom. The atom of hydrogen has a charge of one unit, that of oxygen 8; at the other end of the scale there is uranium, which has a very high charge. > It was found, however, said Dr. Farr, that there were more kinds than one of hydrogen atoms: all, of course, had the characteristic electrical charge of one unit, but there were differences in mass. The ordinary hydrogen atom had a mass of one unit; but there was another which had a mass of two units, and yet another the existence of which was only now realised, which had a mass of three units.

Reason for Different Kinds of Water This difference meant that there were different kinds of water; ?or water was a chemical compound of hydrogen and oxygen in the ratio of two atoms of hydrogen to one of oxygen. "Heavy water" contained hydrogen atoms, which had each a mass of two units, and it was proportionally heavier than ordinary water. More over, it had very different properties: it would not sustain animal life nor allow it to be sustained, and its effect on human beings had not yet been conclusively determined. "How "Heavy Water" is Obtained How is heavy water, which costs £IOOO per litre, obtained? Dr. Farr said that the present method was that of electrolysis—the decomposition of substances by means of subjecting them to an electric current. "Light water" was more easily decomposed than "heavy water" and consequently the latter might be isolated by this method from ordinary water, which, as already stated, was a mixture of the two in the ratio of about 6000 to one. The gradual decomposition of the huge proportion of "light water" was, of course, an expensive process. A method of diffusion, however, might possibly be used, owing to difference in density of the two kinds of water. But "heavy water" by no means exhausted tfca possibilities of this new aspect of science. Not only might there be an intermediate type of water composed of one atom of oxygen, and one of light and one of heavy hydrogen, but there was also the probability of compounds of the extra-heavy hydrogen atom of three units of mass. Moreover, other elements had their light and heavy forms—oxygen, for instance, which had at least two kinds of atoms, one of 16 units of mass and the other of 17. The proportional difference here, of course, was not so great as in the case of hydrogen, where the addition of one unit means the doubling of the mass. Infinite possibilities were afforded in the variations of substances su 'i as alcohol; though the likelihood of this leading to different kinds of intoxication was doubtfully admitted by Dr. Farr. However, as most organic substances were composed of carbon, oxygen and hydrogen, the variations of the last two elements alone would provide an enormous field for investigation. Variations had been found so far in acetic acid and acetylene as well as in water.

Dr. Farr paid a tribute to the heroism of the men who had drunk "heavy water." "But we in New Zealand could hot carry out such experiments even if we haa the courage to do so," he added, "for no 'heavy water' has been isolated here, though work is being done on the matter in Melbourne. The whole question, however, has astounding possibilities. There is very quick growth from small beginnings in science to-day; helium, for instance, was found to exist on the sun only at the end of last century. To-day it is universally used and cheaply obtained. If it had been used, in the airship RlOl there would only have been a difference of a few tons in lifting capacity, but there would have been all the difference between safety and disaster." It may be some time therefore, before "heavy water" is isolated in large quantities in this country. But everyone, in drinking ordinary water, drinks one part in 6000 of "heavy water."