June 24, 1909] 



NATURE 



505 



College (Sir Felix Schuster, Bart.), the dean of the faculty 

 of science (Prof. Millar Thomson, F.R.S.), the dean of 

 the faculty of medicine (Prof. Sidney Martin, F.R.S.), the 

 chairman of the military education committee (Prof. D. S. 

 Capper), the secretary of the Royal Society (Dr. J. Rose 

 Bradford), the dean of the college faculty of medical 

 sciences (Prof. G. D. Thane), and the Jodrell professor of 

 physiology (Prof. E. H. Starling, F.R.S.). 



In his address, given to an audience which filled the 

 lecture theatre, Mr. Haldane outlined the gradual growth 

 of the facilities for the highest education in science which 

 has been witnessed in this country during the past twenty 

 years, a growth which, he pointed out, has completely 

 upset the somewhat pessimistic prognostications of 

 Matthew .Arnold, who, as an authority on this question, 

 expressed the opinion that any extension of the facilities 

 offered by the older universities was most improbable. It 

 is, however, only fair to state that it was with reference 

 to the arts rather than the science side of education that 

 he took this somewhat gloomy view of affairs. Mr. 

 Haldane, who admitted that ho appeared to others to be 

 obsessed with a passion for organisation, while avoiding 

 some of those debatable questions which were so intimately 

 bound up with the work of many of those who 

 listened to him, indicated with exceptional lucidity that if 

 any civilised country is to continue to hold its own, 

 abundant facilities must exist for the pursuit of know- 

 ledge by research, and that it was unnecessary to support 

 this by arguments must have been apparent to his audience. 

 That in the institute of physiology full provision for the 

 highest teaching in this subject is available, not only for 

 our own countrymen, but for those from American and 

 foreign universities, was also indicated by Prof. Starling, 

 who, after speaking of the international bonds of friend- 

 ship which _the study of science does so much to foster, 

 made clear the truism that in such places as this institute 

 the real work is carried out which supplies the medical 

 profession throughout the world with the knowledge 

 requisite for their successful treatment of disease. Those 

 who have the best interests of their profession at heart 

 know that this is so. 



The erection of this institute is largely due to Prof. 

 Starling, whose ideas have been carried out in this build- 

 ing, which, with its admirable arrangements for work 

 and excellent equipment, forms a great addition to the 

 opportunities for teaching and research offered by the 

 I'niversitv of London. 



A' 



THE INVESTIGATION OF GASEOUS 

 EXPLOSIONS.^ 

 T the Leicester meeting (1907) of the British Associa- 

 tion it was suggested that the investigation of 

 gaseous explosions was a matter which might suitably 

 form the work of a committee of Section G (Engineering), 

 and although the subject is chiefly of interest to engineers 

 because of its bearing on the theory of the internal-com- 

 bustion engine, the committee appointed has not confined 

 its attention to questions of a purely practical character, 

 but has discussed many questions of scientific importance 

 which might properly be considered of interest to the 

 physical and chemical sections. 



In order that the labours of the committee might lead 

 to some result within a reasonable time, the work so far 

 undertaken has been mainly a critical examination and 

 discussion of the results of previous investigations with a 

 view to further research, and to this end . the report dis- 

 cusses, at some length, various interesting and important 

 matters which in their opinion require further investiga- 

 tion. 



The essential feature in the operation of an internal- 

 combustion engine is the explosion of a mixture of in- 

 flammable gases by which is formed a complex mixture 

 of nitrogen, carbon dioxide, steam and oxygen, and the 

 performance of the engine depends primarily on the 

 changes of pressure and volume of the gas, and is only 



1 First Report of the British Association Committee appointed for the 

 Investisation of Gaseous Explosions, with Special Reference to Tempera- 

 ture. Presented at the Dublin meeting, 1908. 



NO. 2069, VOL. 80] 



ijifluenced in a slight degree by the nature of the 

 chemical changes and the velocity with which these take 

 place. 



The problem is mainly that of the behaviour of gases 

 at high temperatures, and the properties of such gases 

 are completely defined when the relation between pressure 

 and volume at constant temperature is known, and the 

 internal energy is given as a function of the temperature 

 and the density. The first relation is substantially that 

 expressed by Boyle's law for all gases with which we 

 have to deal, while it is sufticient for the present if the 

 internal energy can be expressed as a function of the 

 temperature, and it is with this internal-energy function 

 that the report chiefly deals. 



Measurements of the internal energy have been carried 

 out, as a rule, with the gas at either constant pressure 

 or at constant volume, and the experiments of Holborn 

 and Austin and Holborn and Henning on air, steam, and 

 CO., at constant pressure, have shown that, with in- 

 creasing temperature, there is an increase in the internal 

 energy, which is probably not a linear function of the 

 temperature. The principal part of our knowledge of the 

 behaviour of gases at high temperatures has, however, 

 been obtained by explosion experiments in closed vessels, 

 and if we could accurately make the necessary corrections 

 for deducing from the observed pressures in a real ex- 

 plosion the pressures reached in an ideal one, we 

 could obtain an accurate value of the internal-energy 

 function. 



The difficulties of making corrections due to the disturb- 

 ing influences are very great, but in spite of this the 

 study of explosion pressures has been mainly responsible 

 for the knowledge we possess of the energy function, and 

 the committee therefore considers this method and the 

 possible inaccuracies in detail. 



If the calorific value of a mixture before combustion is 

 known, and the heat lost at any time after the explosion 

 is determinate, the remaining disturbing causes are due to 

 the want of thermal and chemical equilibrium, and possibly 

 to the motion of the gases : we must therefore determine 

 what effect all these disturbing factors have in altering 

 the observed pressure from which the temperature is 

 inferred. 



Much of the loss of heat appears to be due to direct 

 conduction to the walls of the enclosing vessel, but it is 

 probable that loss by radiation is also important, as in 

 some of the experiments considered, where loss by con- 

 duction was imp-obable, the pressures obtained were con- 

 sistent with a considerable loss by radiation. 



The thermal state of the exploded charge has been the 

 subject of much investigation. In a closed vessel the 

 combustion at the point of ignition is completed before any 

 appreciable rise of pressure takes place, and the flame 

 spreads outwards at a velocity which has been estimated 

 at from 120 to 150 centimetres per second, accompanied by 

 a rise of pressure due to the progress of the combustion. 

 The flame, therefore, spreads in an increasingly denser gas, 

 and since the rise of temperature on explosion is nearly 

 independent of the pressures before ignition, the tempera- 

 tures attained at those places which are reached last by 

 the flame are much below the mean owing to the final 

 adiabatic compression and consequent rise in tempera- 

 ture of the already ignited gas. 



.•\t the moment of maximum pressure the temperature 

 varies enormously, as is shown by the measurements of 

 Hopkinson in an approximately cylindrical vessel of 

 6 cubic feet capacity, where, with a mean tempera- 

 ture of 1600° C, the maximum temperature at the point 

 of ignition was 1900° C, and near the walls about 

 1200° C. 



. The temperature of the wall surface in such a vessel 

 is much lower, and in a gas engine, working under normal 

 conditions with a water-jacketed cylinder, the usual 

 temperature is about 200° C., with a fluctuation of rarely 

 more than 10° C. during the whole cycle. Up to the 

 time of maximum pressure there appears to be no appreci- 

 able equalisation of temperature, but convection and con- 

 duction rapidly obliterate these initial differences. If the 

 specific heat of the gas were constant, the attainment of 

 thermal equilibrium would make no difference to the 



