April 7,11898] 



JV^TUJ^JS 



547 



eminent in science and literature, who have defended their con- 

 victions with great power, ample knowledge, much argument- 

 ative force, and occasional eloquence. At one time the contest 

 was waged with no little fury and bitterness ; it threatened, 

 indeed, like the famous controversy on the proper form of a 

 lightning-conductor during Sir John Pringle's presidency of the 

 Ro)h1 Society, or like the equally famous controversy on the dis- 

 covery of the planet Neptune, to attain the dignity of a national 

 question, far more acute, I should imagine, than that which has 

 just occasioned all right feeling Scotchmen to approach the 

 Queen in Council on the subject of Scotland's proper place and 

 designation in Imperial concerns. 



But the acrimony and ill-feeling have happily long since passed 

 away. There is no longer any need to discuss the question either 

 as an advocate or as a partisan. What I shall attempt to-night 

 is to treat it dispassionately, and, within the compass of an hour, 

 to assess, as impartially as I am able, Watt's true place in regard 

 to this discovery. 



It was, indeed, an epoch-making event. The discovery of the 

 composition of water was as momentous for science as the greatest 

 of Watt's inventions was for social and economic progress. The 

 veiy fact itself, apart from all that flowed from it, was of trans- 

 cendent interest. But to those who had eyes to see, its supreme 

 importance was in its fruitful and far-reaching consequences. It 

 signified nothing less than the passing away of an old order of 

 things, the downfall of a system of philosophy which had outlived 

 its usefulness, in that it no longer served to interpret natural 

 phenomena, but which was rather a hindrance and a stumbling- 

 block to the perception of truth. The discovery at once led to 

 the inception of a more rational and more truly comprehensive 

 theory, which not only explained what was already known, in a 

 fuller, clearer and more intelligible manner, but pointed the way 

 to new facts hitherto undreamt of, which, in their turn, served 

 to strengthen and extend the generalisation which led to their 

 discovery. No wonder, then, that those who loved and revered 

 Watt, and who were rightly jealous of his honour, should have 

 sought to do all in their power to vindicate what they honestly 

 conceived to be his just title to so signal and so fundamental a 

 discovery. 



No man has a juster claim to be regarded as a scientific man, 

 in the truest and noblest sense of that term, than James Watt. 

 The scientific spirit was manifest in him even in boyhood. The 

 vciy circumstances of his condition, his weakly frame, the soli- 

 tariness of his school-life, and the early habits of introspection 

 thus induced in a mind forced to feed only on itself, served to 

 strengthen and develop the instinct. Even his early struggles, 

 and the jealousy of the Glasgow Guilds which forbade him to 

 practise his trade in the burgh in which he had not served an 

 apprenticeship, conduced to mould his character and to de- 

 termine the bent of his mind. Hard and illiberal .as it seemed 

 at the time, the Zunftgeist which drove him to the shelter of 

 the old College in the High Street, and secured for him the 

 abiding friendship of Black and Robison, was in reality the most 

 fortunate circumstance in his career. It brought him directly 

 under the influence of one of the greatest natural philosophers of 

 his age, and so stamped him permanently as a man of science. 

 It would not be difficult to trace how this influence reacted upon 

 all that Watt subsequently did — from the time of his earliest 

 speculations on the loss of energy in Newcomen's engine down 

 to the very last of his mechanical pursuits in the dignified retire- 

 ment of Heathfield Hall. He approached the question of the 

 improvement of the steam-engine as a scientific problem, and 

 under the direct inspiration of the doctrine of the great discoverer 

 of the principle of latent heat. It was this same mental attitude 

 towards scientific truth, the same receptivity for scientific 

 doctrine, the same love of pondering over and speculating upon 

 the true inwardness of things that brought him the friendship of 

 Priestley, Withering, Wedgwood and De Luc, and that ultimately 

 made him a cherished member of the foremost scientific 

 academies of the world. It will occasion little surprise to one 

 who has formed a true perception of his character to learn that 

 Watt was wont, even at periods of great mental depression, and 

 of physical suffering, amidst all the toil and anxious worry of a 

 business surrounded with difficulties, to find peace in the con- 

 templation of natural phenomena, and to spend time in philo- 

 sophical speculation. The shrinking, diffident man, in thus 

 communing with himself and with nature, followed a true and 

 constant impulse to withdraw from the strife and turmoil of the 

 world, and to seek his pleasure and his rest in the silent con- 

 templation of natural truth. No one can look upon that con- 



NO. 1484, VOL. 57] 



templative X»c^ without being struck with its expression of 

 philosophic calm. AVhat deep, genuine pleasure these com- 

 munings brought to th? harassed man may oe gleaned from his 

 correspondence. In .truth, nature intended Watt to be a 

 philosopher of the pattern of Boyle, or Newton, or Dalton ; it 

 was destiny that drove him into the world of affairs where, as he 

 said, he was out of his sphere. It is necessary to dwell for a 

 moment on this aspect of Watt, in order to form a just appre- 

 ciation both of his position and of his merits in regard to the 

 great chemical truth with which his name is associated. 



The man of action is apt to regard the contemplative mind 

 with something akin to contempt. I once heard a bustling, 

 busy man, the head of a large engineering establishment, who 

 had enjoyed the good fortune to be a pupil of Thomas Graham, 

 say of that distinguished philosopher that he was the laziest man 

 he had ever met. He did not say he ' ' ever knew " — for how 

 little he really knew of Graham was evident from the fact 

 that at the period to which he referred Graham's thoughts were 

 deeply occupied with some of the most memorable of his 

 investigations. 



It was in one of these contemplative moods — in what he 

 himself styled his periods of excessive indolence — and as it 

 happened at the very time that the Soho firm was struggling to 

 protect itself against the unprincipled horde that was seeking to 

 infringe Watt's fundamental patent, that he occupied himself 

 with turning over in his mind the outcome of one of his friend 

 Priestley's multitudinous experiments. Watt had long held the 

 view that air was a modification of water, or, as he expressed 

 it in a letter to his friend Black, under date December 13, 

 1782, that, "as steam parts with its latent heat as it ac- 

 quires sensible heat, when it arrives at a certain point it will 

 have no latent heat, and may, under proper compression, 

 be an elastic fluid nearly as specifically heavy as water " : at 

 which point he conceived it would again change its state and 

 become air. As he then relates, he sees a confirmation of this 

 opinion in an experiment of Priestley's made, as he says, " in 

 his usual way of groping about." "As he [Priestley] had suc- 

 ceeded in turning the acids into air by heat only, he wanted to 

 try what water would become in like circumstances. He under- 

 saturated some very caustic lime with an ounce of water, and 

 subjected it to a white heat in an earthen retort. . . . No 

 water or moisture came over, but a quantity of air, equal in 

 weight to the water ... a very small part of which was fixed 

 air, and the rest of the nature of atmospheric air. . . . He has 

 repeated the experiment with the same result." 



About a fortnight later Priestley wrote that he was able to 

 convert water into air " without combining it with lime or any- 

 thing else, with less than a boiling heat, in the greatest quantity, 

 and with the least possible trouble or expense." He added 

 that "the method will surprise more than the effect," but that 

 he would defer " the communication of the hocus pocus of it " 

 until such time as Watt should give him the pleasure of his 

 company in return for the pleasure he was to give Watt in 

 speculating on the subject. 



These experiments, as we shall see in due course, were wholly 

 fallacious ; in following them up with his wonted ardour, 

 Priestley quickly found himself in a maze of contradictions, 

 and ultimately discovered that this seeming conversion was 

 absolutely mythical. 



It may be useful, however, to make one or two comments on 

 these passages at the present juncture. In the first place Watt's 

 opinion as to the relation of water and air, although founded, as 

 he thought, upon a more philosophical basis, simply embodied 

 the teaching of the schoolmen. The notion that the so-called 

 four elements were mutually convertible, or were in essence 

 identical, ran through the doctrine of twenty centuries of 

 teachers. Despite the onslaughts of the Spagyrists, and the 

 author of the "Sceptical Chymist," it permeated the literature 

 of natural philosophy down to the very beginning of this epoch. 

 Watt was insensibly swayed by a belief which had descended to 

 him, like the undying germ, through the ages, and he could no 

 more shake himself free of it than he could get rid of the in- 

 fluence of heredity. The very mode in which he, in common 

 with men of his time, uses the term "air," is an indication of 

 the manner in which the ancient creed limited and cramped his 

 thought. He knew that there were various "airs," but it is 

 very doubtful if he realised that they were essentially different 

 substances. There is abundant evidence in the few chemical 

 papers that he published, and especially in his letters to Black, 

 Priestley, De Luc, Kirwan and others, that he regarded them 



