October 20, 1910J 



NATURE 



517 



which Dr. Bauer has advanced to account for the motion 

 of these charged ions is unsatisfactory in several respects, 

 and he further considers that the experimental evidence 

 which has been brought forward by Mr. Faris to support 

 IJr. Bauer's theory is inconclusive. 



Then followed several reports of committees, which 

 were either outlined or taken as read. These included 

 the report of the seismological committee, in which refer- 

 ence is made to the interesting results on the semi-diurnal 

 change in level (caused by the tide) obtained by Plummer 

 at Bidston Observatory. The meeting of the section then 

 came to an end. 



CHEMISTRY AT THE BRITISH ASSOCIATION. 



T N arranging the programme for the Sheffield meeting 

 -'■ the organising sectional committee had made it the 

 main object to discuss broader questions of interest to 

 other sections rather than to encourage the reading of 

 papers appealing mainly to specialists ; further, in view 

 ol the special character of the industries of Sheffield, much 

 oi the programme was devoted to metallurgical subjects. 

 The results of the meeting fully justified this departure, 

 and the three joint discussions not only proved of the 

 greatest interest, but were most stimulating in character ; 

 indeed, it is probable that in two cases, at least, they 

 will serve as points of departure for much new research. 

 The metallurgical papers were equally stimulating and in 

 harmony with the tone set by the president's address — • 

 the meeting as a whole should do much to inspire the 

 filling of some of the gaps in our knowledge to which 

 Mr. Stead made reference. 



The joint discussion with Section A attracted a very 

 large audience. The subject chosen — combustion — should 

 have had the cooperation of the engineers, who were 

 discussing the report of their committee on gaseous 

 e.\plosions on the same morning, but could not see their 

 way to attend the joint meeting. Prof. Bone presented 

 a report giving a very complete summary of the principal 

 researches upon the chemical aspects of gaseous combus- 

 tion during the past thirty years. He dealt in turn with 

 ignition temperatures, the explosion wave, the pressures 

 produced in gaseous explosions, the influence of moisture 

 upon combustion, the combustion of hydrocarbons, and 

 the influence of hot surfaces upon combustion. This last 

 question is of considerable technical importance, hot 

 surfaces accelerating dissociation, and probably also com- 

 bustion, and hence playing a potent part in the develop- 

 ment and concentration of the heat in gas-fired furnaces. 

 The line of attack followed has been to determine the 

 rates of combination of different gases with oxygen when 

 the reacting mixtures are brought into contact with 

 various solid surfaces at selected constant temperatures. 



Sir J. J. Thomson directed attention to the fact that 

 combustion was concerned, not only with atoms and mole- 

 cules, but also with electrons, i.e. bodies of much smaller 

 dimensions and moving with very high velocities. These 

 may precede the explosion wave and prepare the way for 

 it by ionising the gas. The motion of the ions can be 

 stopped at once by means of a transverse magnetic field, 

 and it would be of great interest to repeat Prof. Dixon's 

 experiments on the photography of th3 explosive wave 

 under such conditions. 



It had been shown by the work of Townsend and others 

 that in carefully dried gases the velocity of the negative 

 electrons might be too times as great as the velocity of 

 the positive electrons. The amount of moisture required 

 to reduce this velocity to its ordinary lower value was 

 exceedingly small, and comparable with that required to 

 initiate chemical change. It was not unlikely that the tw-o 

 phenomena were very closely related. 



In reference to the influence of hot surfaces in pro- 

 moting combustion, it was not improbable that the 

 emission of charged particles from the surface was a 

 factor of primary importance. Hot lime gave out an 

 enormous stream of negative electrons ; hot metals emitted 

 an excess of positive electrons. These electrons might 

 produce very important effects by uniting (perhaps seiec- 



NO. 2138, VOL. 84] 



lively) with moisture, with the oxygen or with the in- 

 flammable constituent of the gaseous mixture. The 

 action of surfaces might ultimately be found to depend 

 on the fact that they formed a support for layers of 

 electrified gas in which chemical changes proceeded with 

 high velocity. 



Sir Oliver Lodge referred to the fact that the velocity 

 of sound was not a constant quantity. If a bullet were 

 to travel with a velocity greater than that of sound the 

 air would be shattered as if by an explosion. This result 

 was in practice prevented by the compression, and con- 

 sequent heating, of the air in front of the bullet, whereby 

 the velocity of sound was momentarily raised to perhaps 

 three times its ordinary value. Whilst hot surfaces pro- 

 moted combustion, cool surfaces had an opposite effect; 

 this was responsible for the production of vast quantities 

 of soot and smoke, especially in firing steam boilers. The 

 discovery of a surface which would promote combustion 

 even at lower temperatures would be of very great value. 



Prof. H. B. Dixon stated that the explosion of hydrogen 

 and chlorine by light was of special interest, as it did not 

 occur in the well-dried gas. Both Mellor and Chapman 

 and Burgess had failed to find any evidence of ignition 

 by light of a mixture of two substances — three kinds of 

 molecules seemed to be necessary. But when once the 

 explosion wave was started it proceeded independently of 

 moisture, and, indeed, was actually most rapid in the 

 dry gas ; the e.xplosion was then propagated by molecular 

 collisions between pairs of molecules. It was not unlikely 

 that invisible compression waves might travel a little 

 in front of the visible flame, the particles being thereby 

 raised to a higher temperature, but remaining uncombined 

 until they collided with one another. 



Prof. Armstrong denied the possibility of any interaction 

 taking place between two substances if neither was an 

 electrolyte. Highly purified materials must be used for 

 work of this kind. Perhaps the most suggestive experi- 

 ment was that of Sir James Dewar, who had purified 

 helium so perfectly by the use of charcoal cooled in liquid 

 air that it would not permit an electric discharge to pass 

 through it, although the presence of the gas was clearly 

 shown by the radiometer. 



A paper on the molecular weight of radium emanation, 

 bv Sir \Vm. Ramsay and Dr. R. W. Gray, was delivered 

 by Dr. Gray, who first described in detail the construc- 

 tion of the micro-balance used, and showed how the exact 

 volume of emanation weighed was determined. The 

 mean value of 221 was obtained for the molecular weight 

 of the emanation, and the fact emphasised that the radium 

 emanation was in every sense a true chemical element. 

 Chemically it is absolutely inert, and the atomic weight 

 shows that it falls into the argon series in the periodic 

 table, filling the second vacant space below xenon. The 

 name " niton " (shining) and the chemical symbol Nt was 

 proposed for the emanation. Sir J. J. Thomson suggested 

 that the name should be left to the Congress of Radiology 

 at Brussels (see N.^ture, October 13). 



The more purely physical papers read at the joint 

 meeting are dealt with in the account of the proceedings 

 of the physical section. 



The report on solubility submitted by Dr. J. V. Eyre 

 is the outcome of a systematic study of the literature ; 

 the material is classified chronologically and according to 

 subject, and contains a brief statement of the main con- 

 clusions arrived at by the various authors. 



The conjoint discussion on the biochemistry of respira- 

 tion was of the greatest value in enabling workers on 

 the subject, representing the three sciences concerned, to 

 correlate their views. Mr. F. F. Blackman, who opened 

 the proceedings, gave a very complete summary of the 

 present position of the subject, dividing it into three 

 sections : — (i) the nature of the chemical reaction (or- 

 complex of reactions) that constitutes respiration ; (2) the 

 extent to which this reaction in the cell conforms to the 

 laws -of general chemistry ; (3) the influence on the pro- 

 gress of the reaction of the peculiar medium (protoplasm) 

 in which it takes place. A summary statement of respira- 

 tion takes the form of the equation for the complete 

 oxidation of glucose, but actually the process is most 

 complicated. The existing theories as to the stages in 



