stituents of Water: giving the history of the Philosophical Apparatus so denominated: the Proofs of Analogy in its Operations to the nature of Volcanoes; together with an Appendix containing an account of Experiments [by Clarke, upon ninety-six mineral substances] with this Blowpipe,' London, 1819, 8vo (reprinted in Otter's 'Life,' ii. appendix vii). About 1816 Clarke, who had been accustomed to submit many of his minerals to the action of the common blowpipe, fell in with the 'Essai d'un art de fusion à l'aide de l'air du feu, par M. Ehrman, suivi des Mémoires de M. Lavoisier,' Strasburg, 1787, in which is described 'the use of hyorogen and oxygen gases propelled from different reservoirs in the fusion of mineral substances, and in aid of the common blowpipe.' While occupied with this treatise he 'saw accidentally at Mr. Newman's in Lisle Street (Leicester Square) a vessel invented by Mr. Brooke for a different purpose' (cf. Brooke's account of it in Thomson's Annals of Philos. May 1810, p. 367). He set Newman to work upon it with his ideas, and the latter at last produced the gas (or oxy-hydrogen) blowpipe. Clarke subjectea some refractory minerals to the action of his instrument, but at last the copper reservoir burst. He then employed the safety cylinder invented by Professor Cumming, and successfully continued his experiments, the results of which he from time to time communicated in the 'Journal of the Royal Institution' and in Dr. Thomson's 'Annals of Philosophy.' An account of Clarke's researches in connection with baiytes and the English ores of zinc is given in vol. ii. of Otter's 'Life' (pp. 348-54). He was a member of several geological societies, English and foreign.
In 1810 Clarke published the first instalment of his 'Travels.' The general title of the work is 'Travels in various Countries of Europe, Asia, and Africa.' There are six quarto volumes (1810-23), rather awkwardly denominated 'parts' and 'sections.' The volumes contain numerous illustrations, some from drawings by Clarke. Only twelve chapters of vol. vi. were prepared for the press by the author, the volume being completed and published after his death by his friend, the Rev. Robert Walpole. Some parts of the work appeared in new editions; vol. i. was translated into German by P. C. Weyland (Weimar, 1817, 8vo). The 'Travels' was well received, particularly the earlier volumes. The total sum paid to Clarke for the work was 6,696l. On 13 Feb. 1817 Clarke was elected librarian of Cambridge University; but his health had been giving way some time before his death, which took place on 9 March 1822 at the house of his father-in-law in Pall Mall. On 18 March he was buried in the chapel of Jesus College. A monument was erected near his grave by the members of the college, and a bust, executed by Chantrey, was subscribed for by his literary friends. A portrait of Clarke, engraved from a painting by J. Opie, R.A., forms the frontispiece to vol. i. of the 'Travels ' and to vol. i. of Otter's 'Life.' Among Clarke's friends were many men of eminence. He had some correspondence with Porson, and with Lord Byron, who spoke highly of the 'Travels.' The letters addressed to Clarke by Burckhardt the traveller are printed in Otter's 'Life,' ii. 276 ff.
Clarke's collection of minerals was purchased after his death by the university of Cambridge for 1,500l. The manuscripts procured by him during his travels were sold (together with some scarce printed books) during his lifetime to the university of Oxford, the offer for them being made in 1808. An account of the manuscripts was afterwards drawn up by Dean Gaisford ('Catalogus, sive Notitia Manuscriptorum quæ a cel. E. D. C. comparata in Bibliotheca Bodleiana adservantur,' &c. 1812, &c. 4to. University Press). Clarke disposed of his Greek coins in 1810, for the moderate sum of a hundred guineas, to Richard Payne Knight, who speaks of them as a 'very valuable addition' to his collection; they probably found their way to the British Museum as part of the Payne Knight bequest.
In addition to the writings already enumerated, Clarke was the author of:
- 'Le Reveur; or, the Waking Visions of an Absent Man' (a periodical work begun by Clarke in September 1796; twenty-nine parts were collected and printed in 1797, but the copies were injured and could not be made up for publication).
- 'The Tomb of Alexander, a dissertation on the Sarcophagus brought from Alexandria, and now in the British Museum,' Cambridge, 1806, 4to.
- 'A Methodical Distribution of the Mineral Kingdom,' Lewes, 1806, folio.
- 'A Letter addressed to the Gentlemen of the British Museum,' Cambridge, 1807, 4to.
- 'A Letter to H. Marsh in reply to certain observations contained in his pamphlet relative to the British and Foreign Bible Society,' Cambridge, 1812, 8vo.
- Two papers in the ' Archæologia ' for 1817— (α) On Celtic Remains discovered near Sawston, β) On some Antiquities found at Fulboum, Cambridgeshire.
- 'On the Composition of a dark Bituminous Limestone from the parish of Whiteford in Flintshire,' Geological Society, 1817.
- 'A Syllabus of Lectures in Mineralogy, containing a Methodical Distribution
