T R E 



T R E 



and rough to the touch, and fcratch glafs when nibbed 

 upon it under water. By this property it may always be 

 diftinguifhed from afbeftus, to which it bears a confiderablt 

 refemblance. 



AJheJlous trcmol'ite {amphiiole blanc vmdfoyeufe of Haiiy) 

 is of various (hades of white. It occurs maffive in wedge- 

 (haped or fplintery concretions. The ftrufture is fibrous 

 and i-adiated : it is tranfliicent on the edges, and fome- 

 what brittle and feftile. The fpecific gravity is 2.683. 

 It melts before the blowpipe into an opaque white mafs. 

 When rubbed or ftruck in the dai-k, it emits a pale reddifh- 

 coloured light : when thrown on hot coals, it gives out a 

 greenifh-colourcd light. 



Albeftous tremolitc occurs moft frequently in granular 

 foliated lime-ftone, or in dolomite. It is fometimes found 

 in chlorite, and more rarely in trap-rocks. It occurs at 

 Glenelg in Invernefsfhire, in Aberdeenfhire, and Icolmkill, 

 and in bafalt at the caflle-rock of Edinburgh. It is found 

 alfo in various parts of Europe, and in granular lime-ftone 

 with augite on mount Vefuvius. 



Common tremolhe {graynmatite, Haiiy) occurs of vari- 

 ous fhades of white, and fometimes dark fmoke-grey. It 

 occurs maffive and cryllallized. The primitive form of the 

 cryftal, according to Haiiy, is an oblique prifm, with a 

 rhomboidal bafe, the planes of which are inclined at an angle 

 of 127° and 53°. The more common form of the cryftals 

 is a very acute rhomboidal prifm, with the edges more or lefs 

 truncated, and the lateral planes longitudinally ftreaked. 



This mineral fplits eafily, not only in the direftion of the 

 planes of the cryftal, but alfo in that of its diagonals. 

 When one of the prifms is broken acrofs, we may obferve 

 8 line ftrongly marked in the direftion of the principal dia- 

 gonal ; hence it may at firft fight be confidered as a twin 

 cryftal, but this is not the faft. 



Common tremolite is tranflucent or femi-tranfparent ; it 

 fcratches glafs, is brittle, and is fufible, but with great 

 difficulty, by the blowpipe. According to Brongniart, 

 the cryftals of tremolite are rarely found pure, but gene- 

 rally contain a portion of the accompanying rock in the in- 

 terior. The conftituent parts are ftated as under : 



It occurs in the fame fituations as afbeftous tremohte, and 

 alfo in metalliferous beds, and fometimes in Terpentine and 

 granite. 



Glaffy Tremolite. — Its colours are the fame as thofe of 

 common tremolite. It occurs maffive, and in acicular cryf- 

 tals. The luftrc is fhining, but in a lefs degree than that 

 of common tremolitc. It is tranflucent and rather brittle. 

 The conftituent parts of this mineral vary in different fpeci- 

 mens. According to Langier, the tremohte from St. Go- 

 thard varies as under : 



Silex - 



Lime 

 Magnefia 

 Water and 1 

 Carbonic acid J 



Though tremohte is arranged under a diftinft fpecies 

 from hornblende and aftinohte by profeflbr Jamefon, it is 

 clalTed under the fame family. In a general view he ob- 

 ferves, that tremolite is charafterifed by its white colours, 



9 



23.0 



23 



aftinolite by its light green colours, and hornblende by its 

 dark green colours. The count de Bournon ftates, that the 

 phofphorefcence of tremohte is owing to an intemuxtare 

 with dolomite, and when the latter mineral is feparated from 

 it by acids, the property is deftroyed. 



TREMON, in Ancient Geography, an ifland fituated near 

 that of Delos, fubjeft to frequent earthquakes. 



TREMONT, in Geography, a town of France, in the 

 department of the Maine and Loire ; 3 miles E.N.E. of 

 Vihiers. 



TREMOR, in Medicine. See Palsy. 



Tremou of the Heart. See PALPITAT^O^f. 



TREMOREL, in Geography, a town of France, in 

 the department of the North Coafts ; 8 miles S. of Broons. 



TREMOUILLE, La, a town of France, in the de- 

 partment of the Vienne ; 6 miles E. of Montmorillon. N. 

 !at. 46° 28'. E. long. i° 7'. 



TREMP, a town of Spain, in Catalonia, on the No- 

 guera Palarefa ; 20 miles N. of Balaguer. 



TREMSBUTTEL, a tovra of the duchy of Holftein ; 

 20 miles E. of Hamburgh. 



TREMULA, m Ancient Geography, a town of Africa, 

 in Mauritania Tingitana, upon the route from Ptocolofida 

 to Tingis. Anton. Itin — Alfo, a town of Hifpania, be- . 

 longing to the Baftitani. 



TRENCH, in Agriculture, a narrow opening or furrow 

 cut in land by the fpade or plough, for the. purpofe of 

 draining or watering, and fome other ufes. Alfo, a fmall 

 opening made in digging and working land over in different 

 cafes, and in laying it up both in ploughing and garden- 

 ing. See Spring and Surface Drain, Watering Land, 

 Ridges, and Ridging-u^. 



The cutting fhould be very exaft for the two firft pur- 

 pofes, the different forts of materials raifed being laid to the 

 different fides of the trenches, which, in the latter cafe, are 

 now moftly made in the wedge form. 



Many of the bogs in Ireland have been drained, and made 

 good ground, by only digging trenches round them. 



Trench Filled-Drain, that fort of furface-drain which is 

 laid with fome kind of material for affording a proper paf- 

 fage to the water in its lower part, the upper being covered 

 in with loofe earth. See SuRFACE-Z'/-ain. 



"TREHCH-Planting, in Agriculture and Gardening, the prac- 

 tice of fetting and putting out plants and other produftive 

 matters in trenches. It is a method which is had recourfe 

 to for many different forts of crops in each of thefe depart- 

 ments of cultivation. In the former for potatoes and fome 

 others, and in the latter for a very great number of plants 

 and roots, as is feen under their different heads. 



It has lately too been praftifed for afparagus, and fome 

 other crops, with very great fuccefs. In planting this va- 

 luable vegetable in this way, it was done in the early fpring, 

 the ground being firft dug to the depth of eighteen inches, 

 and well incorporated with rotten dung quite to the furface ; 

 a trench four or five inches deep was then formed, in which 

 the plants, at the time twelve inches in height, were planted 

 at three inches apart, keeping the tops perfeftly upright, 

 and breaking or hurting the roots as little as poflible, cover- 

 ing them in with the fpade, and treading them gently with 

 the foot ; after which the work was finiftied by a good wa- 

 tering. The plants fcarcely flagged at all, though no care 

 had been taken to preferve the mould about their roots, and 

 not one of them died, but they far finpaffed in the courfe of 

 the fummer thofe in the feed-bed rows, and fome of them 

 were capable of being cut the following year, in confequencc 

 of their great progrcfs. The foil had a large proportion of 

 peat-earth in it. 



Sea- 



