NATURE 



[April i, 1922 



Disintegration of Elements. 



By Sir Ernest Rutherford, F.R.S. 



I HAVE been asked to say a few words about a tele- 

 gram in the Times of March 14 giving an account 

 of a paper communicated to the American Chemical 

 Society at Chicago by Dr. G. Wendt and Mr. C. E. 

 Iron. It reported that, when a powerful condenser 

 discharge at 100,000 volts was sent through a very fine 

 tungsten wire, the filament exploded with a " deafening 

 report," producing a flash estimated to correspond to 

 a temperature of at least 50,000° F. The telegram 

 states : " After the flash he (Dr. Wendt) found atoms of 

 tungsten decomposed into simpler atoms and the result 

 was the change of metallic tungsten into gaseous 

 helium." The experiments were made to investigate 

 whether any atomic disintegration can be effected by 

 such high temperature discharges, and apparently the 

 authors believe that they have obtained positive 

 results. 



We must await a much fuller account of the experi- 

 ments before any definite judgment can be formed ; 

 but it may be of interest to direct attention to one or 

 two general points. During the last ten years many 

 experiments have been recorded in which small traces 

 of helium have been liberated in vacuum tubes in 

 intense electric discharges, and it has been generally 

 assumed that this hehum has been in some way occluded 

 in the bombarded material. On modern views, we 



should anticipate that the disintegration of a heavy 

 atom into lighter atoms, e.g. into atoms of helium, 

 would be accompanied by a large evolution of energy. 

 Indeed, it is to be anticipated that the additional 

 heating effect due to this liberated energy would be a 

 much more definite and more delicate test of disin- 

 tegration of heavy atoms into helium than the spectro- 

 scope. 



Our common experience of the large effect of tem- 

 perature in ordinary chemical reactions tends to make 

 us take a rather exaggerated view of the probable 

 effects of high temperatures on the stability of atoms. 

 While it seems quite probable that momentary tem- 

 peratures of 50,000° F. can be obtained und^r suitable 

 conditions in condenser discharges, it shoufd be borne 

 in mind that the average energy of the electrons in 

 temperature equilibrium with the atoms at this tem- 

 perature corresponds to a fall of potential of only 

 6 volts. In many physical experiments we habitually 

 employ streams of electrons of much higher energy and 

 yet no certain trace of disintegration has been noted. 

 In particular, in Coolidge tubes an intense stream of 

 electrons of energy about 100,000 volts is constantly 

 employed to bombard a tungsten target for long 

 intervals, but no evolution of helium has so far been 

 observed. 



Obituary. 



Prof. A. D. Waller, F.R.S. 



BY the death of Prof. Augustus Desire Waller, 

 on March 11, in his sixty-sixth year, the 

 scientific world has lost an unique personality — a 

 physiologist of international eminence and of excep- 

 tional calibre. 



Waller studied in the Universities of Aberdeen and 

 of Edinburgh, graduated in the former, and commenced 

 his experimental work in Ludwig's laboratory in the 

 year 1878. From here he proceeded to University 

 College, London, whence he was appointed to the 

 lectureship in physiology in the London School of 

 Medicine for Women. He subsequently held the 

 corresponding post in the Medical School of St. Mary's 

 Hospital. In 1902 Waller became Director of the 

 Physiological Laboratory of the University of London, 

 of which, aided by the generosity of his brothers-in- 

 law, and enabled by the wisdom and liberality of the 

 Senate, he had been largely instrumental in securing 

 the foundation. This post he held, amid difficulties, 

 with conspicuous success, until his death. 



Whilst at St. Mary's, Waller had felt the need of 

 and had found the time and energy to establish and 

 equip a library and laboratory, in his home, and it 

 was there that most of his earlier researches were 

 carried out. From there also he supplemented the 

 resources of the University by the unstinted loan 

 both of books and of valuable apparatus. He was 

 closely associated with the Institut Marey from its 

 inception, latterly as vice-president, and took an active 

 part in the direction of its affairs. 



Nearly 200 publications, covering a very wide field, 



NO. 2735, VOL. 109] 



Stand to Waller's credit. Early papers on the circu- 

 latory system led to a study of the electromotive 

 phenomena of the heart beat and to the discovery 

 that an electrocardiogram could be recorded on the 

 human subject. His earliest records with the capillary 

 electrometer, though accurate, were not what he ex- 

 pected them to be. Influenced by this, and misled 

 by an insensitive instrument, he subsequently pub- 

 lished and afterwards withdrew an inaccurate picture 

 of the electrical events in the cardiac cycle. In 

 consequence of this mischance the credit of Waller's 

 discovery has been wrongly attributed to others. 

 Some years later, with the aid of a more perfect instru- 

 ment — Einthoven's string galvanometer^he returned 

 to this work, which had been meanwhile developed 

 and extended by Prof. Einthoven in Leiden. Thanks 

 to Waller, the string galvanometer became now, for 

 the first time, available for clinical diagnosis in London. 

 Its employment spread from his laboratory in all 

 directions, notably to University College Hospital and 

 to the National Hospital for Diseases of the Heart, 

 in the latter of which he was appointed consulting 

 physician. 



This, though perhaps the most notable piece of 

 Waller's electro-physiological work, was a small 

 fraction of its total. He was the pioneer of galvano- 

 graphy in physiology and was the first to record, 

 photographically, the negative variation and the 

 electrotonic currents of nerve, both of which he studied 

 exhaustively. Of especial interest, in this connexion, 

 are (i) his discovery that protracted excitation of a 

 nerve produced the same effect on subsequent negative 



