January ii, 19 12] 



NATURE 



141 



introduced him to physical chemistry, gave rise to 

 further investigation, in the course of which the habit 

 of expressing experimental results by mathematical 

 formulae, learned from Sir William Thomson, turned 

 out to be extraordinarily valuable. In this connection 

 originated the fundamental works on evaporation and 

 dissociation, carried out in great part with his assist- 

 ant, Sydney Young, which first drew the attention of 

 the larger circles of the scientific world upon him. 

 Here also it is suggestive to note how one followed on 

 the other. His intervention in a controversy which 

 was at that time raging in the columns of Nature 

 concerning "hot ice" suggested to him the possibility 

 of determining the relation between vapour pressure 

 and temperature by introducing into a space under 

 the pressure in question a thermometer the bulb of 

 which was covered with the body under investigation, 

 in this case ice. The resulting temperature corre- 

 sponding to the pressure turned out to be so precise 

 that the process was soon developed as a general 

 method of determining vapour pressure. 



These investigations, which have been published in 

 a number of large essays in the Philosophical Trans- 

 actions, gave the impetus w^hich led to the appoint- 

 ment of the still youthful professor to the highly 

 esteemed chair at the University College, London, 

 which Sir William Ramsay still adorns. It is true 

 that at that time the great value of these works was 

 imperfectly recognised, and I remember having an 

 opportunity of pointing out to the authorities of the 

 University College with great emphasis that we had 

 here to do with investigations carrying us consider- 

 ably further than the determinations of the great 

 physicist Regnault, who was then regarded as the 

 first authority on the whole subject. 



At this point began the rapid succession of works 

 which brought Ramsay to the scientific eminence 

 which he still occupies. The measurements of surface 

 tensions up to the critical temperature led to the well- 

 known law which allows us to determine molecular 

 weights in liquids. An occasional lecture experiment, 

 during which magnesium nitride was produced, sug- 

 i;ested to him to cooperate with Lord Rayleigh in the 

 solution of the problem proposed by the latter con- 

 cerning the difference in density between nitrogen 

 derived from the air and artificial nitrogen. 



By heating nitrogen from the air repeatedly with 

 metallic magnesium, he succeeded in producing a gas 

 that became ever denser, and turned out to be decidedly 

 different from nitrogen itself. At the same time, Lord 

 Rayleigh solved the problem of separating nitrogen 

 from a possible other gas by the repetition of an experi- 

 ment devised by Cavendish a hundred years earlier. 

 Both these excellent investigators combined for joint 

 continuation of this work, which led to the discovery 

 of argon, ilic first type of a ik w < ims of elements. 



But when an element of a new type had been found, 

 the periodic law immediately suggested the existence 

 i>f a number of other elements of the same type. Thus 

 Ramsay succeeded in a short time in discovering the 

 > lement helium, belonging to the same group, in 

 NO. 2202, VOL. 88] 



certain rare minerals. An incidental occupation with 

 a litre of liquid air, then first made in London by 

 Hampson, led shortly afterwards to the discovery of 

 three further elements of the same type — neon, krj-p- 

 ton, and xenon — which were separated from each other 

 and described, using in many cases quite novel 

 methods of determining their properties. Thus while 

 other discoverers were satisfied with single new 

 elements, Ramsay discovered a whole class of elemen- 

 tary substances. 



Then when in 1896 Becquerel demonstrated during 

 his stay in Paris his newly discovered dark rays of 

 uranium from which later the discover^' of radium 

 resulted, Ramsay showed the keenest interest, and 

 undertook in his own laboratory an investigation of 

 these phenomena. 



This work led up to the greatest discovery made by 

 our great investigator, the discovery of tht 1. ,il trans- 

 mutation of one element into another. The gaseous 

 emanation of radium, which at first had behaved as 

 an entirely new body, showed after some time the lines 

 of helium, and, finally, it was definitely proved that 

 radium in its spontaneous decomposition produced 

 helium in a perfectly regular way. If Ramsay had 

 not come to know helium beforehand as his own 

 child, so to speak, and if he had not, in the course 

 of his work on rare gases, acquired the skill of work- 

 ing with almost immeasurably small quantities of 

 such substances, he would probably not have succeeded 

 in this capital discovery, which placed him among the 

 very first chemical discoverers. 



Following upon this work. Sir William Ramsay 

 originated a series of other investigations, some of 

 which are not yet finished, and cannot there- 

 fore be dealt with in this place, more especially as he 

 is still at an age at which we may expect great and 

 manifold achievements from him which preclude a 

 final judgrnent upon his work. 



But it may be possible to describe the general type 

 to which Sir William Ramsay belongs as a discoverer. 

 It has already been said that he undoubtedly belongs 

 to the "romantic" type, working with an unusual 

 speed of reaction, and marked by rapid and various 

 productions. The marked peculiarity of this type of 

 investigators, which in.ibles them to train a g^eat 

 number of budding lal. nis and to spur them to extra- 

 ordinary efforts, has been brilliantly brought out. We 

 may regard the physico-chemical school of Sir William 

 Ramsay as the most important chemical school of his 

 country for a large number of years. He has not 

 been spared the fate of the " romantic " school, inas- 

 much as he has on occasion made an error in his dis- 

 coveries. When the unheard-of number of new 

 elements derived from the air rattled down upon the 

 astonished world of chemists, one of these elements, 

 which had been given the name metargon, on account 

 of its similarity with argon, turned out to be carbon 

 monoxide, which had entered the gases by an impurity 

 in the phosphorus. This error did not do much 

 damage, especially since, as Sir William Ramsay re- 

 marks himself, there is always in such a case a large 



