October 22, 1903] 



NA TURE 



611 



•'vpIv charged a radiation and a second emanation, 



!id so on until /le changes cease to produce the usual 



:lect on an electrometer. Whatever the nature of the 

 radio-active material, the amount of radiation it emits in 

 unit time is equal to A. times the amount of radio-active 

 I lement present, where A is a constant for each type of 

 matter, and is unaffected by chemical and physical agencies. 

 I'rof. Rutherford regards the process which goes on in 

 radio-active substances as a gradual breaking up of the 

 atoms of the substance, and this gradual disintegration as 

 I ho cause of the radio-active properties. The electrically 

 neutral atom of a radio-active substance throws off a posi- 

 tively charged body which constitutes the a radiation ; what 

 remains of the atom constitutes the emanation. This again 

 throws off a positively charged body, and the process repeats 

 itself until the positively charged bodies are exhausted, and 

 ihe substance no longer possesses radio-active properties. 



This disintegration theory fits all the known facts, but it 

 involves the existence in the atom of a radio-active substance 

 of a store of energy hitherto unsuspected, amounting in the 

 case of radium to at least lo" ergs per gram. This energy 

 exists, according to Prof. Rutherford, as kinetic energy of 

 motion of the atoms in closed paths with velocities com- 

 parable with that of light, and disintegration is the moving 

 off at a tangent of one or more of the particles of an atom. 

 It this is the case it seems probable that the atomic energy 

 ! elements not yet found to be non-radio-active is of the 



me order of magnitude, and may be set free by methods 

 : which we are not yet cognisant. 



In the discussion which followed Sir Oliver Lodge said 

 the theory put forward by Rutherford seemed to him to 

 be a valuable working hypothesis, very near, if not abso- 

 lutely, the truth. It was supported by Larmor's electrical 

 theory, according to which the atoms of matter should be 

 unstable. 



Lord Kelvin, in a letter communicated to the section, 



I forward another theory as to the nature of the pro- 

 ' -ses going on in radio-active materials. According to it 

 ( ach atom of matter has positive electricity distributed 

 uniformly through its mass, and concentrated at one 

 or more points, in general within it, atomic quantities of 

 negative electricity, to which Lord Kelvin gives the name 

 " electrions. " A normal atom has the necessary number 

 of electrions to neutralise the positive electricity associated 

 with its matter. The a radiation consists of atoms of matter 

 which have less than the normal number of electrions. 

 When they move into matter they quickly pick up the 

 negative charges necessary to render them neutral, and 

 cease to be detected. The j3 radiation consists of electrions 

 thrown off during violent oscillations of the atoms of matter, 

 and are readily absorbed by matter. The 7 radiation con- 

 sists of vapour of the radio-active matter, e.g. radium, 

 which would possess the penetrative power it is found to 

 have if the Boscovichian forces between the atoms of radio- 

 active matter and ordinary matter were small. The large 

 amount of energy radiated is, according to this view, derived 

 from without the atoms, where it exists in a form which we 

 have not yet found a means of detecting. 



Prof. Armstrong pointed out that, as the experiments of 

 Rutherford and Soddy had been made on what was sup- 

 posed to be radium bromide, the dissociation which they 

 believed to be taking place might be of the compound and 

 not of the element. He was disposed to regard Lord 

 Kelvin's theory with favour. 



Mr. Soddy thought ordinary cheinical changes were ex- 

 cluded by the fact that the rate of production of the radi- 

 ations was unaffected by chemical and physical conditions 

 which greatly affected the former. The view Prof. Ruther- 

 ford and he put forward was that at each stage of the 

 process a new element was formed. 



Prof. Dewar gave an account of the experiments on the 

 effects of low temperature on the properties and spectrum 

 of radium carried out partly in conjunction with Sir W. 

 Crookes and recently communicated to the Royal Society. 



Prof. Schuster thought the internal energy more probable 

 than the absorption theory, and questioned whether the 

 instability of the atoms predicted by electrical theory would 

 account for the high velocities of the emanations. He was 

 disposed to regard these high velocities as probably due to 

 some cause not yet known. 



Prof. Larmor agreed with Prof. Rutherford's theory, and 

 pointed out that, just as atoms of matter must have size, 



NO. T773. VOL. 68] 



or a half-size atom would still be an atom, so it may be 

 that the atoms of electricity have size and configuration, 

 and thus account for the complicated structure of the 

 radium atom. 



Mr. Whetham directed attention to the still unexplained 

 fact that the negatively charged emanation seemed to 

 deposit more readily on negatively than on positively 

 charged bodies, and Dr. Lowry, after recounting some e.\- 

 periments on the flash of light seen when certain sub- 

 stances are crushed, suggested that the emanation might 

 be a modification of a constituent of the atmosphere, e.g. 

 helium. C. H. Lees. 



CHEMISTRY AT THE BRITISH 

 ASSOCIATION. 



'X'HE Southport meeting of Section B proved to be one 

 ■'• of the most successful held during recent years ; the 

 meetings were largely attended, and a keen interest was ex- 

 hibited in the proceedings of the section. After the reading 

 of the presidential address (Nature, p. 472), Prof. J. 

 Campbell Brown described an apparatus for determining 

 latent heats of evaporation, in which a known quantity 

 of heat, generated electrically in a platinum wire, is 

 absorbed in converting a liquid at its boiling point into 

 vapour at the same temperature ; very concordant results 

 are obtained. 



In a paper on some derivatives of fluorene. Miss Ida 



CeHs 

 Smedley showed that whilst fluorenone | j>C=0, 



CeH/ 

 IS orange-red in colour, the corresponding sulphur derivative, 

 thiofluorenone, is intensely red ; the radicle >CS has thus 

 a greater tendency to produce colour than the carbonyl 

 group. In a paper on the action of diastase on the starch 

 granules of raw and malted barley, Mr. A. R. Ling showed 

 that the starch derived from both raw and malted barley 

 is dissolved and hydrolysed by diastase at a temperature 

 below its gelatinising point, and that the optical and re- 

 duction constants differ according to the sample of grain 

 from which the starch is derived. Evidence was adduced 

 in two other papers on the action of malt diastase on potato 

 starch paste, one by Mr. A. R. Ling and the other by Mr. 

 A R. Ling and Mr. B. F. Davis, that when diastase is 

 heated in aqueous solution at 6o°-7o° for a short time, the 

 molecule of the enzyme becomes so changed that it no 

 longer yields the same products when it acts on potato 

 starch paste. 



Dr. H. C. White described the chemical and physical 

 characteristics of the so-called mad-stone, which, in accord- 

 ance with a superstition current in the southern States of 

 America, is used to detect and cure the bites of venomous 

 snakes or rabid animals ; the mad-stone is found to be a 

 concretionary calculus from the gullet of the male deer, and 

 is devoid of discriminative or curative powers. 



Prof. E. A. Letts, Mr. R. F. Blake, and Mr. J. S. Totton 

 read a paper on the reduction of nitrates by sewage, in 

 which it was shown that, when potassium nitrate is added to 

 the effluent from a septic tank, practically all the nitrogen 

 is evolved in the free state or as nitric oxide ; the oxygen of 

 the nitrate is evolved as carbon dioxide. 



A method for the separation of cobalt from nickel and 

 for the volumetric determination of cobalt was described 

 by Mr. R. L. Taylor ; it is based on the fact that cobalt is 

 precipitated quantitatively as a black oxide from neutral 

 solutions by barium or calcium carbonate in presence of 

 bromine water. The black oxide has the composition 

 Co,0,, or Co,0„. 



Prof. J. Dewar, F.R.S., contributed a description of the 

 more recent results obtained from his investigations at low 

 temperatures ; he described the methods by which he has 

 succeeded in determining the densities of solid hydrogen, 

 nitrogen, and oxygen, the methods of producing solid 

 hydrogen and nitrogen, and the methods by which he has 

 been able to determine the latent heats, specific heats, and 

 the coefficient of expansion of liquid hydrogen. 



A paper on the application of low temperatures to the 

 study of biological problems, by Dr. Allan Macfadyen, is 

 printed in another part of the present issue (p. 608). 



Mr. J. Hubner and Prof. W. J. Pope, F.R.S., gave a 

 paper on the cause of the lustre produce(I on mercerising 



