GRE
G R E
It is only gravitation, or gravity thus blended with the cen- trifugal force, that we can meafure by our experiments. However, methods have been found to diftinguifh what re- mains of primitive gravity, and what has been deflroyed by the centrifugal force. See Maupertuis loc. cit.
GRAUPEN, a term ufed by the German miners to expfefs the refiduum of any ore after the regulus, or metalline part is run from it. Thus the ores of bifmuth leave behind them, after the regulus is melted off, an earthy fubftance called bifmuth graupen, with which, mixt with flints and an alkali, they make a kind of fmalt, not diftinguifhable from the true fmalt made from cobalt. Philof. Tranfact. N° 390.
GRAY, in zoology, a name given in fome counties of Eng- land to the badger. See the article Taxus.
Gray is alfo ufed in fome places for a fpecics of wild duck, more commonly known by the name of the gadwall. See the article Gadwall.
GRAYLING,or Umber, theEnglifh name for the fifh called by authors thymallus, and thymus, and by Artedi made a fpecies of coregonus. See Thymallus and Coregonus.
GREEN (Cyd.) — The fineft method of giving this beautiful colour to glafs is this. Take five pound of cryftalline metal, that has been paffed feveral times through water, and the fame quantity of the common white metal of polverine, four pound of common polverine fritt, and three pound of red lead ; mix the red lead well with the fritt, and then put all into a pot in a furnace. In a few hours the whole mafs will be well purified ; then caft the whole into water, and fepa- rate, and take out the lead ; then return the metal into the pot, and let it ftand a day longer in fufion ; then put in the powder of the refiduum of the vitriol of copper, and a very little crocus martis, there will be produced a moft lively and elegant green, fcarcc inferior to that of the oriental emerald. There are many ways of giving a green to glafs, but all are greatly inferior to this. Neri's Art of Glafs, p. 55.
Green fijh, in the fifh trade, a name given to the cured cod fifh which has been caught and preferved in Greenland. milugbby,-K&. Pifc. p. 166. Sec the article Cod fifh.
Green-/j£w;, or Green-hue, in our old writers, the fame with writ in forefts, csV. Manwood, Par. 2. cap. 6. num. 5. Vid. Terms of Law.
GRE.EN-/.ww/f.r. The length of green-houfes muft be pro- portioned to the number of plants intended to be preferved in them, and cannot therefore be reduced to rule ; but their breadth fhould never be more than twenty feet in the clear, and the length of the windows fhould be at leaft equal to the breadth, or depth of the houfe ; and thefe muft be car- ried quite up to the cieling, that there may be no dead air in any part of the houfe, and they fhould come down with- in ten or twelve inches of the floor. In a fmall green-houfe they mould not be lefs than four feet broad, and in a large one they ought to be fix. The piers between the windows muft be as narrow as may be to fupport the building, for which reafon they fhould either be of ftone, or of hard burnt bricks.
If the piers are made of ftone, they fhould be twenty inches wide in front, and flopcd off" behind to ten inches, by which means there will be no comers to take off the rays of the fun. If they are of brick, they will require to be at leaft two feet in front, but they fhould be in the fame manner Hoped oft" behind. Over the green-houfe may be rooms for drying and preferring feed*,, roots, &c. and behind it a place for tools and other purpofes ; and both tbefe behind, and the rooms above, will be of great ufe in keeping off the frofts, fo that the wall between thefe need not be of more than two bricks in thicknefs.
The floor of the green-horfe, which fhould be laid either with marble, ftone, or flat tiles, muft be raifed two feet above the furface of the adjoining ground, or if the fituation be damp, at leaft three feet -, and under the floor, about two feet from the front, it will be very advifeable to make a flue of ten inches wide, and two feet deep ; this fhould be car- ried thf whole length of the houfe, and then returned back along the hinder part, and there be carried up into funnels adjoining to the tool-houfe, by which the fmoak may be car- ried off. The fire place may be contrived at one end of the houfe, and the door at which the fuel is put in, as alfo the afti grate, may be contrived to open into the tool-houfe, and the fuel being laid in the fame place, the whole will be out of fight. The ufc of fires muft, however, be very fpar- ing in this place, and it is not one winter in three or four that will require them in any part, only when the weather is very fevere, and the froft cannot well be kept out any other way, this is an expedient that is good to have in readi- nefs, as it may fave a whole houfe of plants. There muft be a number of truflels, with forms of wood upon them, to fupport the pots of plants, the talleft to be placed hind- moft, the loweft within four feet of the windows ; and all the infide of the green-houfe mould be white-wafhed, or painted white, to reflect as much as poflible the fun's rays. The placing the euphorbiums, cereus's, and other fucculent plants among orange trees, and other common green-houfe
plants, is always deftructive of them, by making them re- ceive an improper fort of effluvia, which plants of that kind imbibe very freely. They fhould therefore be placed in two wings built at each end of the green-houfe, which, if well contrived, will be a great beauty, as well as ufe, to the building. Thefe wings may be made capable of a greater warmth alfo, by more flues, and may be made to contain a hot-bed of tanners bark for the raifing many of the tender plants, natives of warm climates. Milter's Gard. Diet.
Greek mujlard, an Englifh name for the herb dittander, or pepperwort. See Lepidium.
Green filver, the name of an antient cuftom within the ma- nor of Writtel in the county of Efiex ; which is, that every tenant, whofe fore-door opens to Greenbury, mall pay an half- penny yearly to the lord, by the name of green filver. Blount.
Green wax, is ufed where effreats arc delivered to the fheriffs out of the Exchequer, under the feat of that court, made in green wax to be levied in the feveral counties. This word is mentioned in the flat. 43 Ed. 3. c. 9. And 7 Hen. 4. c. 3. Terms of Law.
GREGARIOUS birds, are fuch as do not live folitarilv, but affociate in flights or coveys, a great many together in company.
GRENAILLE, a name given by the French writers to a pre- paration of copper, which the Chinefe ufe as a red colour in fome of their fineft china, particularly for that colour which is called oil red, or red in oil. The china ware co- loured with this is very dear. The manner in which they procure the preparation is thus : they have in China no fuch thing as filver coined money, but they ufe in com- merce bars, or maffes of filver ; thefe they pay and receive in large bargains, and among a nation fo full of fraud as the Chinefe, it is no wonder that thefe are often adulterated with too great an alloy of copper. They pafs, however, in this ftate in the common payments. There are fome occafions, however, fuch as the paying the taxes and con- tributions, on which they muft have their filver pure and fine : on this occafion they have recouife to certain people, whofe fole bufmefs it is to refine the filver, and feparate it from the copper and 1 the lead it contains. This they do in furnaces made for the purpofe, and with very convenient vefTels. While the copper is in fufion, they take a fmall brufh a'nd dip the end of it into water, then ftriking the handle of the brufh, they fprinkle the water by degrees upon the melted copper; a fort of pellicle forms itfelf by this means on the furface of the matter, which they take off while hot with pincers of iron, and immediately throwing it into a large veffel of cold water, it forms that red powder, which is called the grenaille; they repeat the operation, every time they in this manner feparate the copper ; and this furnifhes them with as much of the grenaille as they have occafion for in their china works. Obfervations fur les Coutumes de l'Afie, p. 309.
GRESLING, in ichthyology, a name given by the Germans to the gobius fluviatiiis, or common gudgeon, which is very frequent in their fmaller rivers.
GRESSURA, a word ufed by fome writers, to exprefs the part between the pudenda and the anus. See the article Perinjeum.
GREWIA, in botany, the name given in the hortus ?nala~ baricus, and continued by Linnaeus to a genus of plants, the characters of which are thefe : the cup is a perianthium, compofed of five obleng, erect, lanceolated leaves ftanding open, and coloured within. The flower is compofed of five petals, fomewhat fmaller than the leaves of the cup, and edged with a foliacious rim at the bafe. The ncctarium is compofed of certain little fcales, inferted one in the bafe of each petal ; thefe are thick, and fomewhat incurvated, and furrouhd the ftile. The ftamina are very numerous fila- ments inferted in the bafe of the gernien, and of the length of the flower ; the apices or antherze are roundifh. The piftil is a long columnar receptacle, erect and edged with a pentangular rim; it is terminated with a roundifh mer- men. The ftile is capillary, and is of the length of the fta- mina ; the ftigma is obtufe and quadrifid ; the fruit is a quadrangular berry with four cells; the feeds are globofe. Linnesi Gen, Plant. 439. Hort. Mai. Vol. 5. p. 46.
GREWT, in mineralogy, a word ufed by our miners to ex- prefs earth, but particularly that earth found in the flat coun- tries, and in the banks of rivers in their fearches after mi- neral veins, which is different in colour and nature from the reft of the bank or bottom. This they always underftand to have been wafhed off from the neighbouring hills, in the time when the fhoad ftones, by which they train their new mines, were alfo wafhed down, that is at the univerfal deluge ; and this wherever found, proves of great ufe to them in thefe rcfearches, as it fhews which way the wafh from the hill has run, and directs them how to trace the reft, and where to look for the fhoad ftones with any probability of fuccefs.
They generally examine the banks of rivers, where they have been worn away by land floods, in order to find thefe grezvts, and then examine, in a ftrait line with the next
hill,
