Also 7 -ie, 7–8 -y, (8 tripela). [= F. tripoli (16th c. in Godef., Compl.), f. Tripoli, a region in North Africa, or town of the same name in Syria, where found.] A fine earth used as a polishing-powder, consisting mainly of decomposed siliceous matter, esp. that formed of the shells of diatoms; called also infusorial earth or rollen-stone.
1601. Holland, Pliny, XXXV. vi. II. 530. Tripolie or goldsmiths earth.
1665. Hooke, Microgr., Pref. With a little Tripoly, rub them till they come to be very smooth.
1777. G. Forster, Voy. round World, II. 355. A sort of tripoly, which is called rotten-stone by some miners.
1797. Encycl. Brit. (ed. 3), VII. 608/2. The common tripela, or Tripoli, used to polish glass and stones.
1830. Lyell, Princ. Geol., I. 214. That admixture of clay and silica, called tripoli.
1869. trans. Pouchet’s Universe (1871), 21. Some tripolis of a red colour are employed in house painting.
b. attrib.
1677. Plot, Oxfordsh., 28. That very lasting brightness … receiv’d from the Gold-smiths Tripoli-stone.
1825. J. Nicholson, Operat. Mechanic, 755. To polish Varnish.—This is effected with pumice-stone and Tripoli earth.
1839. G. Roberts, Dict. Geol., Tripoli powder..., used for polishing fossils, &c. It is itself the remains of fossil insects.
1868. Dana, Min. (ed. 5), 199. Tripolite … (c) Tripoli slate (Polishing slate …), a slaty or thin laminated variety, fragile.
Hence Tripoline a., of or pertaining to tripoli; Tripolite Min., an infusorial variety of opal-silica, constituting one of the kinds of tripoli; Tripolith [Gr. λίθος stone], trade name for a kind of cement: see quot.
1759. Da Costa, in Phil. Trans., LI. 193. The layers of fossil wood in this mountain, having been saturated with the Tripoline particles, thereby composed a stone.
1868. Dana, Min. (ed. 5), 199. Infusorial Earth, or Earthy Tripolite, a very fine-grained earth looking often like an earthy chalk, or a clay.
1882. Athenæum, 30 Sept., 438/1. The new binding material ‘tripolith,’… is composed of sulphate of lime (gypsum), coke powder, and precipitated oxide of iron.
