NATURE 



60 1 



SATURDAY, MAY 13, 1922. 



CONTENTS. PAGE 



Contemporary Alchemy 601 



A History of Chemistry. By Sir T. E. Thorpe, 



C.B., F.R.S 603 



Antarctic Polychaeta. By Prof. W. C. M'lntosh, 



F.R.S 604 



European Archaeology. liy A. K 605 



Indian Game-Birds 606 



Water Flow m Pipes. By F. C. L 606 



Recollections of a Geologist 607 



Our Bookshelf 608 



Letters 10 the Editor : — 



Science at the Post Office.— Sir W. Noble; The 



Writer of the Article 690 



Discoveries in Tropical Medicine. — Lieut. -Col. A. 



Alcock, F R.S >. .611 



Nectar .Sipping Birds.— Right Hon. Sir Herbert 



Maxwell. Bart, F.R.S. . . .612 



Aeroplane Crashes : the " Hole in the Air," the 

 "Spin."— Dr. W. Galloway; Prof. L. Bairstow, 



F.R.S 6i2 



The Blood-cells of the Oyster.— Dr. J. H. Orton . 612 

 Periodical Phenomena in the Temperature Functions 

 of Certain Properties of the Metals. — Dr. G. 



Borelius • 613 



Observations of Comets. — W. F. Denning . . 613 

 A Proposed I>aboratory Test of the Theory of 



Relativity. —Dr. Robert W. Lawson . . 6x3 

 Artificial Disintegration of the Elements (with 



Diagrams). By Sir Ernest Rutherford, F.R.S. . 614 

 Organisation for Visual Instruction. By Dr. C. W. 



Kimmins 617 



Obituary :— 



Arthur Bacot. By Dr. C.J. Martin, F.R.S. . 618 



Louis Ranvier 620 



Current Topics and Events 621 



Our Astronomical Column 623 



Research Items 624 



Science in Bohemia. {Illustrated.) By Prof. Bohuslav 



Brauner 625 



Wheat Prices and Rainfall in Western Europe . 627 



The Teaching of Natural History. By F. K. . . 628 



A Modified Octet Theory 629 



University and Educational Intelligence . . 629 



Calendar of Industrial Pioneers 630 



Societies and Academies 631 



Diary of Societies 632 



Editorial and Publishing Offices : 



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Advertisements and business letters should be 



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Editorial communications to the Editor. 



Telegraphic Address: PHUSIS, LONDON. 

 Telephone Number : GERRARD 8830. 



NO. 2741, VOL. 109] 



Contemporary Alchemy. 



IN another part of this issue we print the concluding 

 part of Sir Ernest Rutherford's account of his 

 researches on the disintegration of the atoms of some 

 elements by means of a-rays. The theory of atomic 

 structure which postulates a small positive nucleus and 

 sparsely distributed surrounding electrons indicates 

 that a permanent change in the atom requires the 

 disruption of the nucleus itself. This nucleus is also, 

 according to modern views, an association of simpler 

 parts, probably only units of positive and of negative 

 electricity, which are the same in all atoms. If this 

 arrangement can be altered, we should change one 

 atom into another, or others. The forces binding the 

 components of the nuclei of stable atoms must be very 

 great, and in overcoming them a large expenditure of 

 energy will be required. The swift a-particle expelled 

 from radium is by far the most concentrated source of 

 energy known, and by firing these a-particles through 

 matter, collisions with the atomic nuclei might be 

 expected to break up the latter. 



This is the idea on which the work is based, and it 

 has now, as Sir Ernest explains, received remarkable 

 experimental confirmation. He found that, with 

 nitrogen gas, hydrogen atoms were liberated, but these 

 did not appear with oxygen or carbon dioxide. Such 

 particles are, of course, produced in hydrogen gas, or 

 substances containing hydrogen, but simple precautions 

 ensure that the hydrogen particles otherwise observed 

 do not come from hydrogen existing as an impurity in 

 the materials. The H-particles from hydrogen have 

 a range in air of 30 cm., and by interposing mica screens 

 equivalent to this absorption, no such particles are 

 observed as scintillations on a zinc sulphide screen. 

 With nitrogen interposed between the source of a-rays 

 and the mica screen, however, numerous scintillations 

 appear. 



By placing a thin film of metal over the source 

 of a-rays, and having oxygen between this and the 

 screen, the production of H-particles from metals 

 could be investigated. Solid compounds were dusted 

 over gold foil, which itself gives no H-particles. 



With the exception of helium, neon, and argon, all 

 the elements up to atomic weight 40 were examined. 

 In no cases except boron, nitrogen, fluorine, sodium, 

 aluminium, and phosphorus were any H-particles 

 observed. No element of atomic weight greater than 

 phosphorus (31) gave any effect, but only particles of 

 range not less than 32 cm. were sought. 



A very striking result was observed in the case of 

 aluminium, since nearly as many H-particles were shot 

 off in the backward as in the forward direction of the 



