d'Auteroche, seeing the crowd en carmagnole as the carts passed through the streets, raised a smile as he said disdainfully, in allusion to the confiscation of his effects: "What annoys me is to have such disagreeable heirs." They were guillotined in the order of their names on the indictment. Lavoisier saw fall the head of his father-in-law, and was himself the fourth to suffer. In common with all his companions, he bore himself with dignity, and met his end calmly and with courage. The spectacle of such fortitude awed the crowd into silence, and no reproach or insult reached the ears of the dying man.

Thus perished, at the age of fifty-one, one of the most remarkable men in the history of science. All that was mortal of him was thrown into the cemetery of the Madeleine, and the place of his interment was forgotten. The news of this great crime profoundly affected the intellectual world. There was not a scientific body in Europe that failed to give utterance to its sense of shame and sorrow. With the fall of Robespierre this feeling penetrated France. On October 22, 1795, Lalande pronounced an éloge on Lavoisier before the Lyceum of Arts, and in the midst of the extraordinary revulsion of popular feeling which preceded the days of the Directory the same body decreed a solemn funeral ceremony in his honour. It was, in truth, a lugubrious farce, marked by all the extravagances of taste and sentiment which were then in fashion, and it was crowned by an éloge . . . from Fourcroy! Time-serving and timorous as ever, Fourcroy had no other extenuation than an appeal to the memories of the Great Terror. "Carry yourselves back to that frightful time . . . when terror separated even friends from each other, when it isolated even the

members of a family at their very fireside, when the least word, the slightest mark of solicitude for the unfortunate beings who were preceding you along the road to death, were crimes and conspiracies." For Fourcroy to plead that he was pusillanimous hardly serves to exculpate him. He would have us believe that he was powerless to avert the catastrophe he now affects to deplore; but he stands charged, on his own showing, with participation in acts which largely contributed to it, and the charge rests heavily on his

memory.

VII

PRIESTLEY, CAVENDISH, LAVOISIER, AND LA RÉVOLUTION CHIMIQUE

THE PRESIDENTIAL ADDRESS TO THE CHEMICAL SECTION OF THE BRITISH ASSOCIATION, LEEDS, 1890

LEEDS has one most notable association with chemistry of which she is justly proud. In the month of September 1767 Dr. Joseph Priestley took up his abode in this town. The son of a Yorkshire cloth-dresser, he was born in 1733 at Fieldhead, a village about six miles hence. His relatives, who were strict Calvinists, on discovering his fondness for books, sent him to the Academy at Daventry to be trained for the ministry. In spite of his poverty and of certain natural disadvantages of speech and manner, he gradually acquired, more especially by his controversial and theological writings, a considerable influence in Dissenting circles. A pressing invitation and the prospect of one hundred guineas a year induced him to accept an invitation to take charge of the congregation of Mill Hill Chapel here. He was already known to science by his History of Electricity, and the effort was made to attach him still more closely to its cause by the offer of an appointment as naturalist to Cook's Second Expedition to the South Seas. But, thanks to the interven

tion of some worthy ecclesiastics on the Board of Longitude who had the direction of the business, and who, as Professor Huxley once put it, "possibly feared that a Socinian might undermine that piety which in the days of Commodore Trunnion so strikingly characterised sailors," he was allowed to remain in Leeds, where, as he tells us in his Memoirs, he continued six years, very happy with a liberal, friendly, and harmonious congregation," to whom his services (of which he was not sparing) were very acceptable. "In Leeds," he says, "I had no unreasonable prejudices to contend with, and I had full scope for every kind of exertion." 1

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We have every reason to feel grateful to the "worthy ecclesiastics," since their action indirectly occasioned Priestley to turn his attention to chemistry. The accident of living near a brewery led him to study the properties of "fixed air," or carbonic acid, which is abundantly formed in the process of fermentation, and which at that time was the only gas whose separate and independent existence had been definitely established. From this happy accident sprang that extraordinary succession of discoveries which earned for their author the title of the Father of Pneumatic Chemistry, and which were destined to completely change the aspect of chemical theory and to give it a new and unexpected development.

I have been led to make this allusion to Priestley, not so much on account of his connection with this place as for the reason that, as it seems to me, there has been a disposition to obscure his true relation to

1 Leeds still enjoys one of the fruits of Priestley's insatiable power of work in her admirable Proprietary Library. He seems to have suggested its formation, and was its first honorary secretary.

the marvellous development of chemical science which made the close of the last century memorable in the history of learning. Our distinguished fellow-worker, M. Berthelot, the Perpetual Secretary of the French Academy, has recently published, under the title of La Révolution Chimique, a remarkable book, written with great skill, and with all the charm of style and perspicacity which invariably characterises his work, in which he claims for Lavoisier a participation in discoveries which we count among the chief scientific glories of this country. From the eminence of M. Berthelot's position in the world of science his book is certain to receive in his own country the attention which it merits, and as it is issued as one of the volumes of the Bibliothèque Scientifique Internationale it will probably obtain through the medium of translations a still wider circulation. I trust that I shall not be accused of being unduly actuated by what Mr. Herbert Spencer terms "the bias of patriotism," in deeming the present a fitting occasion on which to bring these claims to your notice with a view of determining how far they can be substantiated.

All who are in the least degree familiar with the history of chemical science during the last hundred years, will recognise, as I proceed, that the claims which M. Berthelot asserts on behalf of his illustrious predecessor are not put forward for the first time. Explicitly made, in fact, by Lavoisier himself, they were uniformly and consistently disallowed by his contemporaries. M. Berthelot now seeks to support them by additional evidence and to strengthen them with new arguments, and asks us thereby to clear the memory of Lavoisier from certain grave charges which lie heavily on it. You have doubtless anticipated that these claims