tion, the second molecule of carbonic acid in the latter leaves it to combine with the caustic lime, the result being that all the lime (two pounds) is deposited in the form of the insoluble carbonate, and the 540 gallons of water remain clear and soft. Water so softened would require only one-third the quantity of soap to make a lather ; also there would be no fur on the surface of boilers. The advantage of Clark's process over other softening processes is that no derivative compounds remain behind in the water. 'This character,' says Clark, 'is as fortunate as it is rare in chemical processes.' Another advantage is that the quantity of organic matter in the water is greatly reduced by the precipitation of the chalk, the water in large bulk having the natural pure blue colour of uncontaminated water, the process is somewhat expensive, from the numher of reservoirs required; but the cost of the caustic lime is more than balanced by the high price got for the chalk thrown down. Although the process was favourably reported on to the government in 1851 by Graham, Miller, and Hoffmann, it was opposed by the metropolitan water companies, and has been adopted at only a few places. The following is a complete list of the larger works: Plumstead, 1854 (absorbed in 1861 by the Kent Water Company, who do not soften); Caterham, 186l; Chiltern Hills, 1807 (supplying Aylesbury, Tring, &c.); Canterbury, 1869; and Colne Valley, 1876 (supplying the district as far as Harrow, Hendon, and Edgware, from the reservoirs at Bushey). The process is also in use at private establishments, such as Castle Howard, Mentmore, Henley Park Place, and the Herbert Hospital. Clark's sanguine forecast was, 'The process is of such utility and such necessity to London that it will be in operation as long as London last.'
[Biographical Memoir of Dr. Thomas Clark, by Alexander Bain, in the Transactions of the Aberdeen Philosophical Society, 1840-84.]
CLARK, THOMAS (1820–1876), landscape painter, born in Whiteside, Stirlingshire, 14 Nov. 1820, son of William Clark, W.S., sheriff-substitute of Clackmannanshire, was educated at Dollar. In the course of his school days he sustained an injury to his shoulder, the effects of which crippled him through life. Having early resolved to become a painter, he prosecuted at Edinburgh the necessary studies.
Clark exhibited first at the Royal Scottish Academy when twenty years of age, and was elected an associate of the Academy in November 1865. At that period he resided at No. 11 Castle Street, Edinburgh. He painted both in water and oil colours; his subjects were chiefly scenes in Scotland, but were sometimes taken from localities south of the border. He was in the habit of wintering in the south, a few years before his death, which took place at Dundarach, Aberfoyle, 7 Oct. 1876. Among his better works may be mentioned, 'Waiting for the Ferry,' 'A Quiet Morning on Loch Awe,' 'Spring,' 'Summer,' and 'The Farm Yard, Woodside, Surrey.'
[Private information.]
CLARK, WILLIAM (d. 1603), catholic priest, received his education at the English college, Douay, where he arrived on 6 Aug. 1587 (Records of the English Catholics, i. 216). Two years later he proceeded to the English college at Rome, and he was one of eight priests sent thence to England in April 1592 (ib. 298; Foley, Records, vi. 117). He took an active part in the violent disputes between the secular clergy and the Jesuits consequent on the appointment of Blackwell as archpriest, and he was one of the thirty-three priests who signed the appeal against Blackwell dated from Wisbech Castle, 17 Nov. 1600 (Dodd, Church Hist. ed. Tierney, iii. Append, p. cxliv). An unsuccessful attempt was made to give to the first clause of the breve of Clement VIII, in favour of the appellants (5 Oct. 1602), the appearance of restoring to them faculties which had been recently withdrawn, and at the same time to exclude Clark, Watson, and Bluet from its operation (ib. p. clxxxi). In 1602 he was an inmate of the Clink prison, Southwark. He and William Watson, another of the appellant priests, were induced to join the mysterious plot of Sir Walter Raleigh, Lord Cobham [see Brooke, Henry, d. 1619], and others against James I. On being apprehended Clark was committed to the Gatehouse at Westminster, and thence removed to the Tower. He and most of the other prisoners were afterwards conveyed to Winchester under a strong guard, where they were tried and condemned on 15 Nov. 1603. The leaders in the conspiracy were pardoned; but George Brooke [q. v.], Clark, and Watson suffered the punishment of traitors at Winchester on 29 Nov. Sir Dudley Carleton, who was present, says: 'The two priests that led the way to the execution were very bloodily handled.' He adds that Clark 'stood somewhat upon his justification, and thought he had hard measure; but imputed it to his function, and therefore thought his death meritorious, as a kind of martyrdom' (Hardwicke, State Papers, i. 387).
He wrote 'A Replie unto a certain Libell latelie set foorth by Fa. Parsons, in the name
