Forms: 7 fylter, 7–9 filtre, 6– filter. Also 6 philter. [ad. mod.L. filtrāre, f. filtrum FILTER sb. Cf. F. filtrer.]
1. trans. To pass (a liquid) through a filter, or some porous medium, for the purpose of removing solid particles or impurities. Also with off. Also absol.
1576. Baker, Jewell of Health, I. i. 2. The dropping caused by a Lyste, or peece of Woollen cloth, cut and fashioned into the forme of a Tongue, which maner of dooing (the Chymistes name Fyltring).
1594. Plat, The Jewell House of Art and Nature, Chim. Concl., 23. Some use to filter this Lee divers times.
1605. Timme, Quersit., I. ix. 36. They dissolue manie times, they fylter, and coagulate, not to the vttermost poynt of drynesse: but drawing out onely of that water twoo thirde partes and more.
1671. Grew, The Anatomy of Plants, I. i. § 31. The Sap … not being filtred through so fine a Cotton as the Coats be.
1747. Wesley, Prim. Physic (1762), 86. Filtre the Tincture thro’ Paper.
1784. Cowper, Task, II. 507.
| Sages after sages strove | |
| In vain to filter off a crystal draught | |
| Pure from the lees, which often more enhanced | |
| The thirst that slaked it, and not seldom bred | |
| Intoxication and delirium wild. |
1812–6. J. Smith, Panorama Sc. & Art, II. 355. Putrid and stinking water may be rendered sweet by filtering it through charcoal-powder.
1838. T. Thomson, Chem. Org. Bodies, 200. We then filter, washing the blue-coloured sulphate of lime remaining on the filter till it becomes red.
1853. Soyer, Pantropheon, 27. The liquid was several times filtered, till it became quite clear.
b. transf. and fig.
1830. Gen. P. Thompson, Exerc. (1842), I. 291–2. The Chamber of Deputies, though filtered through every process which policy could invent for diminishing the operation of the national feeling, declared in terms which had no fault but that of being not sufficiently explicit, their refusal to co-operate with such a ministry.
1856. Emerson, Eng. Traits, First Visit, Wks. (Bohn), II. 5. The passage would no doubt strike you more in the quotation than in the original, for I have filtered it.
1885. Manch. Exam., 10 Jan., 5/3. At present his instructions to counsel are filtered through a solicitor.
1892. Pall Mall G., 4 May, 1/3. Each of these images is ‘filtered’ through a colour screen.
c. Said of the filtering material.
1854. Woodward. Mollusca (1856), 37. The sea-weed filters the salt-water, and separates lime as well as organic elements.
1882. Watts, Dict. Chem., II. 648. Paper which filters slowly may be improved in quality by this treatment.
2. To cause (a liquid) to pass drop by drop, or slowly, through a porous medium (now only in passive); also, † to give forth through the pores, exude, rare.
1583. Stanyhurst, Æneis, III. (Arb.), 71.
| For the tre supplanted, that first fro the roote seat is haled, | |
| With drop drop trilling of swart blud filtred abundance. |
1644. Digby, Two Treatises, I. xx. 183. That streame [of atoms] … clymbing and filtring it selfe along the stones streame, draweth it out of its course.
1860. Maury, Phys. Geog. Sea, x. § 466. Numerous rivers discharge themselves into the Mediterranean, some of which are filtered through soils and among other minerals which yield one kind of salts or soluble matter.
3. intr. To pass as through a filter; to percolate. Also with away, down.
Cf. F. filtrer, used refl. and intr. in this sense.
1798. W. Blair, The Soldier’s Friend, 155. The water in the river, from its natural propensity to find its level, will filter through the sand, and come clear into the bason.
1864. Marsh, Man & Nature, 437. A stratum of snow which prevents evaporation [from the soil] causes almost all the water that composes it to filter down into the earth.
1882. Vines, Sachs’ Bot., 687. Water will filter through the cell-walls into the cavities of the wood.
transf. and fig. 1821. Clare, The Village Minstrel, and Other Poems, I. 207, Solitude.
| As ’neath hazels I have stood | |
| In the gloomy hanging wood, | |
| Where the sunbeams, filtering small, | |
| Freckling through the branches fall. |
1868. Yates, The Rock Ahead, I. I. iii. 158. A perpetual stream of fashionables, political people, and the usual ruck of young men who are met everywhere, would filter from ten till one through her little drawing-rooms in Clarges-street.
4. To obtain by filtering. Also transf. rare.
1794. Pearson, in Phil. Trans., LXXXIV. 387. The liquid filtered from these solutions had a sweetish and bitterish taste.
1845. Darwin, Voy. Nat., i. (1879), 5. Fine dust, which appeared to have been filtered from the wind by the gauze of the vane at the mast-head.
Hence Filtered. Filtering ppl. adjs. Also Filterer, that which filters or serves as a filter.
1727. Bailey, vol. II., Filtered, strained through a Paper, Cloth, etc.
1794. Schmeisser, in Phil. Trans., LXXXIV. 421. The remaining filtered liquor was saturated with purified pot-ash.
1809. J. F. Archbold, Patent, No. 3225. It [sea water] is passed through a filterer.
1821. Clare, The Village Minstrel, and Other Poems, II. 162. Sonnets. xiv. To an Hour-Glass.
| Old-fashioned uncouth measurer of the day, | |
| I love to watch thy filtering burthen pass. |
1830. Tennyson, Ode to Memory, iv. The filter’d tribute of the rough woodland.
1853. Soyer, Pantropheon, 412. The basin had been filled with … eight barrels of filtered water.
1859. Cornwallis, New World, I. 38. There is nothing so bad, but that it might be worse, thought I; and on the same principle, that there is nothing so good but that it might be better. For instance, the stretcher might have been directly under this water filterer, and that would have been worse.
