1649 W. Blith Eng. Improver xix. 112 A Mud or Sludg, that lyeth frequently in deepe Rivers which is very soft.

1707 J. Mortimer Whole Art Husbandry (1721) II. 70 In that Water I put the Earth.., so as to make it a meer soft Sludge or Mud.

1745 Beverley Beck Act ii. 2 Choaked and warped up by the sludge and soil brought in by the tides.

1783 Philos. Trans. 1782 (Royal Soc.) 72 364 When we saw it, the moist filth, or sludge, at bottom..was two or three inches deep.

1822 W. Scott Fortunes of Nigel I. iii. 55 The natural scent of the ooze and sludge left by the reflux of the tide.

1875 S. Smiles Boy's Voy. Round World xi. 113 A wide stretch of ground was covered by a thick deposit of sludge.

1946 L. D. Stamp Britain's Struct. & Scenery iii. 20 In tundra lands the sub-soil remains permanently frozen whilst the surface thaws in summer and, where there are steep slopes, masses of sludge slide downhill.

1959 G. H. Dury Face of Earth xv. 181 The loess records cold, very dry climate. The underlying sludge was formed in a preceding episode of moister conditions when the topsoil thawed annually.

1817 W. Scoresby in Ann. Reg., Chron. 534 The first appearance of ice whilst in the state of detached crystals, is called by the sailors sludge.

1820 W. Scoresby Acct. Arctic Regions I. 227 Sludge consists of a stratum of detached ice-crystals, or of snow, or of the smaller fragments of brash-ice floating on the surface of the sea.

1885 Encycl. Brit. XIX. 328 The ice first forms in thin, irregular flakes called ‘sludge’, and when this is compact enough to hold snow it is known as ‘brash’.

1962 Sunday Express 4 Feb. 19/2 Pyjama stripes—navy, ‘sludge’ or ‘smog’ on white.

1977 Vogue Feb. 90/1 From a commanding frilly and deep sludge dress, Merle Park changes into her working clothes.

1702 T. Savery Miner's Friend 60 Sluge or Fine Dirt..will do my Engine no Injury.

1840 J. Hodgson & J. Raine Hist. Northumberland: Pt. II III. 319/2 That sort of ammoniacal sleck or sludge which comes from kitchens.

1883 R. Haldane Workshop Receipts 2nd Ser. 53/2 They [sulphites] act well with salt water, giving a soft sludge, which should be readily removed by the blow-pipe.

1920 C. F. Cross & E. J. Bevan Text-bk. Paper-making 144 It constitutes a ‘sludge’, practically devoid of useful felting properties.

1921 Dict. Occup. Terms (1927) § 143 Causticiser man,..when action is complete, allows sludge to settle, runs off caustic liquor and agitates sludge with fresh water to extract last traces of caustic.

1933 Charlottesville (Va.) Daily Progress 22 May 6/5 The death of five men in a drainage vat at the Hess and Drucker Tannery was being investigated... The fifth was a would-be rescuer, who plunged into the tank of sludge.

1965 New Statesman 19 Nov. 809/4 (advt.) Industrial Chemist required by Company dealing in sludges & effluents of all kinds.

1974 J. Dyson P.M.'s Boat is Missing xxx. 180 The sludge of crude oil in the bottom of tanks.

1757 tr. J. F. Henckel Pyritologia 341 All these cobalds or pyrites must previously be parted from the barren minerals, by stamping and washing, and made into a pure sludge.

1778 W. Pryce Mineralogia Cornubiensis 226 Some have concluded, that Tin in the state of sludge or slime, by length of time, must grow and increase.

1839 A. Ure Dict. Arts 752 It is impossible to prevent some of the finely attenuated portions of the galena called sludge, floating in the water.

1898 Daily News 5 July 9/5 Further tenders have just been accepted for a quantity of sludges valued at over 1,000l.

1877 J. B. Denton Sanit. Engineering 266 The third gradation of the solid matter in sewage known as ‘sludge’.

1887 Times 26 Aug. 9/4 The sediment or sludge left at the bottom of the precipitation tanks.

1839 R. S. Robinson Naut. Steam Engine Explained 123 To prevent any sludge, &c. from issuing out at the mouth of the pipe, and falling on the decks of the vessel.

1912 R. B. Dole in Rogers & Aubert Industr. Chem. iii. 47 If magnesium and sulphates are comparatively low or if suspended matter is comparatively high the scale is soft and bulky and may be in the form of sludge that can be blown or washed from the boiler.

1937 E. Pull Boiler-house Pract. xv. 147 Every opportunity should be taken to remove accumulations of grease, scale, sludge and soot.

1955 R. E. Kirk & D. F. Othmer Encycl. Chem. Technol. XIV. 940 This led to the system..of maintaining at all times in the boiler water a small but sufficient excess of phosphate ion so that all calcium ion entering with the feed water would be precipitated as a loose sludge of calcium phosphate rather than as a hard scale.

1871 W. Morgans Man. Mining Tools 134 A sludger which is fitted with an inside piston..in order to suck the sludge into the cylinder.

1911 Dana & Saunders Rock Drilling ii. 21 The shales will often form a sludge containing such proportions of large and small particles as to cake on the bit.

1933 R. S. Lewis Elem. Mining xiv. 422 Where much sludge is made it is very important to have the water return with sufficient velocity to lift the heaviest particles in the sludge.

1963 Gloss. Mining Terms (B.S.I.) iii. 13 Sludge, rock cuttings produced by the drill bit.

1885 Encycl. Brit. XVIII. 719/1 The acid ‘sludge’, consisting of the oil of vitriol combined with the impurities of the oil and forming a black tarry liquid, settles to the bottom..and is drawn off.

1938 Oliver & Spangler in A. E. Dunstan et al. Sci. Petroleum IV. 2765/1 At refineries on the sea coast acid sludge was frequently discharged into the ocean.

1954 R. E. Kirk & D. F. Othmer Encycl. Chem. Technol. XIII. 493 Most refineries hydrolyze the light nonlube sludges, effecting an incomplete separation of acid tars from the weak impure acid.

1965 O. T. Fasullo Sulfuric Acid v. 127 The tendency of sludges to evolve sulfur dioxide.., in addition to the enormous quantity in which sludges are necessarily produced by the petroleum industry, makes these materials worthy subjects for the application of pollution control measures.

1900 Jrnl. Inst. Electr. Engineers 29 274 In copper refining with high current densities less anode sludge is formed.

1900 Jrnl. Inst. Electr. Engineers 29 274 A yet higher temperature, viz. 60°C., increases the quantity of sludge.

1901 B. Blount Pract. Electro-chem. 35 The rationale of electrolytic refining is to transfer this copper, by the selective action of the current, from the anode to the cathode and to leave the impurities behind as a sludge.

1948 T. C. Elliott Electr. Accumulator Man. iii. 26 The piling up of sludge..and the creation of possible short circuits through the growths clinging to the tubes..must be avoided.

1977 Brodd & Kordesch tr. Bode Lead-acid Batteries iii. 222 A Pb content of more than 5% is supposed to cause difficulties during the formation of positive plates (swelling or warping or extensive sludge formation).

1920 Whittaker's Electr. Engineer's Pocket-bk. (ed. 4) 245 When the transformer is examined, it is found that the windings and core are covered with a reddish-brown flocculent deposit or sludge.

1927 Jrnl. Soc. Chem. Industry 8 Apr. 135 t/2 The sludge deposits which are sometimes found in hollow crankpins..are due evidently to decomposition products of the oil being thrown out by centrifugal action.

1941 D. F. Miner Insulation Electr. Apparatus iv. 81 The purification of oil used in circuit breakers and transformers consists principally in the removal of water, carbon, and sludge.

1973 G. Zwick Everyman's Guide Car Maintenance (1974) vi. 153 If the motorist has consistently been using a high grade heavy duty oil, the chances are that the interior of the engine is clean, with a bare minimum of sludge and other residues.

1947 Science 7 Nov. 436/2 Many human patients have various degrees of unexplainable edema... These can now be examined for sludges.

1972 H. I. Bicher Blood Cell Aggregation ii. 27 All of this provides strong additional support for considering sludge as..a possible antecedent to thrombosis.

1855 J. Ogilvie Suppl. Imperial Dict. Sludge-doors, in boilers, closed openings by which the matter deposited at the bottom..can be taken out.

1846 A. Young Naut. Dict. 313 There are also sludge-holes at the ends of the water passages between the flues, by which the deposit can be raked out.

1853 E. K. Kane U.S. Grinnell Exped. (1856) xxxi. 268 Suddenly a seal rose close by him in the sludge-ice.

1896 Durham Arch. Trans. (1901) 26 A circular tank or cistern provided with an outflow or ‘sludge’-pipe at the bottom.

1887 Dict. Archit. (Archit. Publ. Soc.) (at cited word) Sludge pit, a cesspool.

1883 W. S. Gresley Gloss. Terms Coal Mining 227 Sludge pump, a short iron pipe or tube..with which the boremeal is extracted from a borehole.

1889 Pall Mall Gaz. 31 July 6/1 It will then..be pumped through pipes extending along a jetty into the sludge ships, for conveyance and discharge into the German Ocean.

1869 R. D. Blackmore Lorna Doone II. xvi. 207 Here and there the ice was fibred with the trail of sludge-weed, slanting from the side.

1977 D. Clark Gimmel Flask v. 82 I thought this sort of sludge brown varnish paint went out with Queen Victoria.

1971 Vogue 1 Oct. 127 Sludge green knit tights.

1972 Guardian 8 Feb. 11/2 Cheesecloth smock shirt..natural, yellow, sludge green, red or blue.

1976 Times 3 Feb. 9/7 Single breasted coat..sludge green with maroon overcheck.

1977 Listener 22 Dec. 855/4 He's a moray eel, a sludge-grey reptilian lurker.

1962 ‘A. Lejeune’ Duel in Shadows vii. 91 An Englishman in a sludge-coloured raincoat.

1979 S. Gainham in G. Hardinge Winter's Crimes XI. 69 The woman in sludge-coloured tweed.