j8S 



NATURE 



[September 22, 1910 



important part of his professional duties to travel frequently 

 and far. I have never been able to settle to my own 

 satisfaction the maximum income which a department of 

 geography might usefully spend, but I have had consider- 

 able experience of working a department the income of 

 which was not very far above the minimum. Until now the 

 Oxford School of Geography has been obliged to content 

 itself with three rooms and to make these suffice, not 

 merely for lecture-rooms and laboratories, but also for 

 housing its large and valuable collection of maps and other 

 materials. This collection is far beyond anything which 

 any other university in this country possesses, but it 

 shrinks into insignificance beside that of a rich and 

 adequately supported Geographical Department like that 

 of the University of Berlin. This fortunate department 

 has an income of about 6000L a year, and an institute 

 built specially for its requirements at a cost of more than 

 150,000/., excluding the site. In Oxford we are most 

 grateful to the generosity of Mr. Bailey, of Johannesburg, 

 which will enable the School of Geography to add to its 

 accommodation by renting for five years a private house, 

 in whiiii there will temporarily be room for our students 

 and for our collections, especially those relating to the 

 geography of the Empire. But even then we can never 

 hope 10 do what we might if we had a building specially de- 

 signed for geographical teaching and research, .\gain. Lord 

 Brassey and Mr. Douglas Freshfield, a former President 

 of this Section, have each generously offered 500/. towards 

 the endowment of a professorship if other support is forth- 

 coming. All this is matter for congratulation, but I need 

 hardly point out that a professor with only a precarious 

 working income for his department is a person in a far from 

 enviable position. There is at present no permanent work- 

 ing income guaranteed to any Geographical Department 

 in the country, and so long as this is the case the work 

 of all these departments will be hampered and the train- 

 ing of a succession of competent men retarded. \ do not 

 think that I can conclude this brief address better than 

 by appealing to those princes of industry who have made 

 this great city of Sheffield what it is to provide for the 

 Geographical Department of the University on a scale 

 which shall make it at once a model and a stimulus to every 

 other university in the country and to all benefactors of 

 universities. 



lONISATION OF GASES AND CHEMICAL 

 CHANGE.' 

 'T'HE term "catalytic"' was introduced by Berzelius to 

 ■'■ describe a number of chemical actions which would 

 only take place in the presence of a third substance, which 

 itself was apparently unchanged throughout the reaction. 

 The first cases of such actions were investigated by Sir 

 Humphry Davy in 1817. He showed that many mixtures 

 of gases were caused to unite in the presence of finely 

 divided platinum at temperatures far below those at which 

 union ordinarily took place. Some years afterwards 

 Faraday investigated similar actions, and attempted to 

 explain them by a supposed condensation of the gases on 

 the surface of the metal. 



Thirty years ago Prof. H. B. Dixon investigated the 

 behaviour of carbon monoxide and oxygen when they were 

 dried as completely as possible, and he discovered that in 

 these circumstances electric sparks caused no explosion. 

 Some years before Wanklyn had discovered that purified 

 chlorine did not act on sodium, but he did not identify the 

 impurity, now known to be a trace of water, which causes 

 the vigorous action which takes place in ordinary circum- 

 stances. 



In 1882 Cowper investigated the action of dried chlorine 

 on several metals, and found that the removal of moisture 

 in many cases inhibited the reaction. 



In the following year, working in Prof. Dixon's labora- 

 tory at Balliol College, I found that purified carbon could 

 be heated to redness in dried o.\ygen, and that sulphur 

 and phosphorus could be distilled in the same gas without 

 burning. In the investigations which followed, some thirty 

 simple reactions have been tried by myself and others. It 

 has been shown that hydrogen and chlorine can be exposed 



at the Royal Institution on Friday. March 11. In- 

 F.R.S. 



NO. 2134, VOL. 84] 



to light without explosion, ammonia and hydrogen chloride 

 mixed without union, sulphur trioxide can be crystallised on 

 lime, ammonium chloride and mercurous chloride give un- 

 dissociated vapours, hydrogen and oxygen can be exposed 

 to a red heat without explosion, and lastly, in 1907, nitrogen 

 trioxide was obtained as an undissociated gas for the first 

 time by carefully drying the liquid and evaporating into a 

 dried atmosphere. 



The amount of water necessary to carry on these chemical 

 reactions is extremely small, certainly less than i mg. in 

 300,000 litres. There is no accepted explanation of its 

 catalytic effect, and in the same way the catalytic power 

 of platinum is still a mystery. Dr. Armstrong's theory, 

 that only water which is capable of conducting an electric 

 current is capable of bringing about these chemical 

 actions, seems to be supported by the fact that water can 

 be formed in heated tubes containing very pure hydrogen 

 and oxygen without the explosive combination of the 

 gases taking place. That great purity does affect the 

 chemical activity of water was proved by an experiment 

 shown during the lecture. Two tubes, one containing 

 water of a very high degree of purity and the other con- 

 taining ordinary distilled water, were placed side by side 

 in the lantern. Into each was filtered some liquid sodium 

 amalgam, and while vigorous effervescence was seen in the 

 less pure water, the very pure specimen was apparently 

 without action for some minutes, and even at the end of 

 the lecture its action had not attained the same vigour as 

 that in the other tube. 



In 1893 Sir J. J. Thcn-.son {Phil. Mag., xxxvi., 

 321) showed that if the combination of atoms in a 

 molecule is electrical in its nature, the presence of 

 liquid drops of water, or drops of any liquid of high 

 specific inductive capacity, would be sufficient to 

 cause a loosening of the tie between the atoms, and this 

 might result in chemical combination of the partially freed 

 atoms to form new molecules. He showed in the same 

 paper that drying a gas very completely stopped the passage 

 of a current of 1200 volts. In the same year I was able 

 in the same way to prevent the passage of discharge from 

 an induction coil', a discharge which would traverse a spark 

 gap of three times the distance in undried gas. 



Shortly after the discovery of Rontgen rays, it was found 

 that they would ionise a gas through which they passed. 

 At the time it was thought that this ionisation was similar 

 to that taking place in electrolysis. If this were so the 

 rays would probably cause chemical union to take place 

 even in a dried gas, and accordingly Prof. Dixon and I 

 undertook some experiments on the subject, which were 

 published in a joint paper (Chem. Soc. Jour., 1896^. The 

 results were negative ; no chemical action could be detected. 

 Since that time the ionisation of gases has been shown to 

 be of quite a different nature. The negative ion has been 

 shown to be a particle of the mass of about 1/ 1500th that 

 of the hydrogen atom, and the positive ion is the residue. 

 Since the ionisation of gases is different from that in electro- 

 lysis, the retention of this term is much to be deprecated. 

 It is suggested that the term ionisation should be retained 

 for electrolytic dissociation, and for the different process 

 which take's place in gases under the action of Rontgen 

 ravs. Sic, a new name, electromerlsm, should be adopted. 

 The electron would thus be the negative electromer._ 



It is probable that electrolysis and true ionisation may 

 take place in gases, as in the decomposition of steam by 1 

 electric sparks of a particular length. An experiment 

 recently devised seems to show that in mercury vapour, 

 which ordinarily consi-ts of atoms, something of the nature 

 of ionisation without electrolysis can take place. If oxygen 

 be admitted to the interior of a mercury lamp from which 

 the current has just been cut off, a considerable quantity 

 of mercuric oxide is produced, although the temperature of 

 the lamp (about 150°) is far lower than would suffice to 

 bring about the union of ordinary mercury vapour with 

 ox\gen. 



In order to test further the question as to whether 

 electromerlsm can bring about chemical change, I have 

 investigated the action of radium bromide on very pure 

 and dry hydroSen and oxygen. The gases were sealed up 

 'with some radium bromide contained in an open silica 

 tube. The containing vessel was provided with a vacuum 

 gauge, by means of which the combination of i '5000th 



