Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/636

 EAR

a fediment of a fort of mud. This is to be thrown away, and the dew, when feparated from it, is to be filtred clear, and evaporated to a drynefs, the remainder is a greyifh Earth, which is the true Earth of dew ; this is Very light and friable, and is of a foliated ftructure in the mafs, looking like fo many leaves of brown paper, fprcad very thin and even over one another. Phil. Tranf. N°. 3.

This Earth, expofed to a fmart fire, loofes its foliated tex- ture, and runs into a mafs, rcfembling a mixture of fait and biimftone melted together, but it is not at all inflamma- ble. This, ground on a levigating ftone, tinges the water to a purplifh colour. A pound of this Earth, properly treated by calcination and elixiviation, will yield an ounce of a pure and white /alt, fomewhat rcfembling nitre. The chy- niifts have been at great pains to procure this Earth, but they do not feem yet to ha> ~ made any very important ufe ot it, and, in all probably, it is no other than that common fpar which we know to be contained in all water, and which en- crufts the fides of our teakettles, and other veflels, in which water is often boiled. We know, by manifold inftanccs, that fpar is rarifiablc into vapour with water, and therefore jt would be a greater wonder if dew were found not to contain it, than that it does.

E a rths of mineral waters — All mineral waters contain Earth of fume kind, though very different in quantity and in nature. Thefc are found, in different waters, of very different co- lours and appearances, fome white, fome grey, fome yellow- ifh, fome reddifh, and fome brown. They are alfo as dif- ferent in their qualities as in their form, fome of them are foluble in acids, others are not fo ; fome ftifible in the fire, others not ; and fome retain their natural colour after burning ; others change it in the fire. By this we learn, that fome arc marly, others argillaceous, others ochrcous, and fome fandy ; others there are which are produced by the concre- tion of certain juices, (aline or fulphureous, and others not fo. Some arc limply mineral, others are metallic. And as many of thefc are very different from any of the known Earths, even in their pure and feparate ftate, they are yet much lefs diftinguifhahle when mixed one with another, as they very frequently arc in the waters of even our common fprings, much more fo in the mineral medicinal ones. The fimplc infufions of certain fulphureous mineral Earths may notably alter the waters of wells and fountains, without having any thing of thofe Earths remaining, after their di- ftillation, in the fame manner as nothing is feparable, by art. from certain liquors, rendered emetic by antimony. Tht hot mineral waters may contract fome alteration from the ful- phureous and bituminous matters which they meet with in their courfe ; for thefc fubftanccs all contain fubtile falts, which hot water may take up, and carry away with it.

Compound Earths, in natural hiftory, are a clafs of foflile bodies, aurally confounded with the genuine and fimple Earths, as if fubflances of the fame kind, but being of a very different nature and origin. They are foflils compofed of argillaceous and marly particles, feparated and divided by adventitious matter, and never found free from thofe admix- tures, or in the ffatc of pure fimple marls or clays. Of this clafs of foflils there are two general orders; thofe of the one are known bv the name of loams, and are compofed of fund and clay ; and thofe of the other are called moulds ; thefe are the Earths that vegetables grow in, and are com- pofed of argillaceous and marly particles, feparated by fand. fmall pebbles, and the gritt of ftone, and ufually intcrmix'd with, and enrich'd by, the putrify'd remains of animal and vegetable fubftances : Of each of thefe there are feveral ge- nera, Hiil's Hift. of Foflils. See the articles Loam and Mould.

Earth Bag, in fortification. See Sand Bag.

Earth5^j, in hufbandry, &c. are a very common fence about London, and in feveral other parts of England. Where ftones are not to be had cheap, thefe arc to be preferred to all other fences, both for foundnefs and lafting.

7 he beft manner of making them is this : Dig up fome turf in a grafly place, a fpitdeep, or nearly to the breadth of the fpade, and about four or five inches thick, lay thefe turft's with the grafs outward, even by a line on one fide, and on the back- iide of thefe lay another row of turff, having a foot fpace of fulid ground on the outfide, to prevent the bank from flipping in, if it fhould any way be faulty. On the outfide of this make a ditch, or elfe let the fides be lowered both ways with a flope two foot deep, and there will be no pafture loft bv the fence, becaufe it will bear grafs on both fides. 'I he Earth that is dug out of the ditches, or from the flopes, muff be thrown in between the two rows of turf, till the middle is made level with the reft. Then lay on two more rows of turff" in the fame manner, and with more of the Earth fill up, and make level as before. Let this method be continued till the bank is raifed four foot high, or more if necefiary, only obferving, that the higher it is to be carried; the wider the foundation muft be made. As the bank i; carried up, the fides muft not be raifed perpendicular, but floping inward both ways, fo that at the top it may be about two foot and a half wide. This fort of fence, when made with lc!s care, and faced with clay, is left naked, and ferves

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very well in fome places ; but when it is thus managed with the turf, the joining of the feveral pieces are hid in a little; time, by the growth of the grafly part of the turf on each fide, and it makes a beautiful fence, of as green and pleafant a colour as the reft of the field. Mortimer's Hufbandry, 12.

The great improvement upon this plan, is the planting quick- fets, or young white-thorn plants, in the middle of the top of the bank. The Earth on each fide of thefe may be raifed up with a fort of wall, and the rain that falls all preferved for the plants. This plenty of water, and depth of fine Earth makes the young plants grow quicker and more vigoroufly than any other way ; and the moft beautiful of all hedges is propagated this way. When this fort of hedge is young, there muft be placed on each fide of it a fliort dry hedge, of about a foot high, to keep the fhecp from cropping the young plants, but this may be taken away after a little time. There is one caution necefiary in regard to the making of thefc banks, which is, that they muft never be made in a very dry feafon, becaufe if much rain fhould follow, the Earth of the bank would fwell and burft out, or fpoil the fhapc of the bank ; but if this fhould happen, it is eafily enough repaired. This beautiful fence may be made at a fmaller price than thofe unaccuftomed to thefc things may imagine. In good digging ground, where men work for fourteen pence a day, it may be made and planted with quick for two millings a pole. It may he made proper for the keeping in of deer, only by the fmall addition of planting, at every eight or ten foot diftance, a poft a little flanting, with a mortifc in it ; let this ftand about two foot above the bank, and into the mortifes all along, put a rail made of a bough of any tree, no deer will ever go over this, nor can they creep under it, as they often do when a pale tumbles down. The quick, on the top of this bank, may be kept clipped, and will grow very thick, and afford the beft inciter for cattle of any fence in ufe with us. Mortimer's Hufbandry.

Earth Pitch. See Pjssasphaltum,

Earth Pucerons, in natural hiftory, a name given by authors to a fpecies of puccron very fingular in its place of abode. In the month of March, if the turf be raifed in feveral places in any dry pafture, there will be found, under fome parts of it, clufters of ants, and, on a farther fcarch, it will be ufually found, that thefe animals are gathered about fome pucerons of a peculiar fpecies. Thefe are large, and of a grey- ifh colour, and are ufually found in the midft of the clufters of ants. See Puceron.

The common abode of the feveral other fpecies of pucerons is on the young branches or leaves of trees ; as their only food is the fap or juice of vegetables, probably thefc Earth kinds draw out thofe juices from the roots of the grafles and other plants, in the fame manner that the others do from the other parts. The ants that conduct us to thefe, are alfo our guides where to find the greater part of the others ; and the reafon of this is, that as thefe creatures feed on the faccharine juices of plants, they are evacuated from their bodies in a liquid form, very little altered from their original ftate; and the ants, who love fuch food, find it ready prepared for them, in the excrements which thefe little animals are continually voiding. It has been fuppofed by fome, that thefe were the common pucerons of other kinds, which had crept into the Earth to prcferve themfelves from the rigour of the winter. But this does not appear to be the cafe, for they are ufually found in places very diftant from trees or plants on which they fhould be fuppofed before to have fed ; and it is very certain, that though many of thefe infects are killed by the cold, yet many efcapc, and are found very early in the fpring, fucking the buds of the peach tree. There is no doubt of thefe creatures being in a feeding condition when under- ground, becaufe otherwife the ants would have no temptation to follow them ; and it is equally certain, that the feveral fpecies of the pucerons, like thofe of the caterpillar kinds, have each their peculiar herbs on which they feed, many of them dying of hunger, rather than feeding on any other; and it is therefore not at all likely, that thefe Earth pucerons had been ufed to feed on leaves of trees and plants, and had left that food for the roots of grafs. Reaumur, Hift. Inf. vol. 6- p- 79-

The opinion of their being a diftincl fpecies is alfo ftrengtb- ened by this, that there are many other fpecies which find their nourifhment at the roots of plants. Mr. Juflieu difco- vercd a peculiar fpecies at the roots of the lychnis; and Mr. Reaumur feveral others at the roots of camomile, yarrow, and other, plants. He goes fo far as to believe, even that the number of fubterraneous fpecies may be equal to that of thofe which are found above-ground, and that, upon the whole, the fpecies of this little infect may be equal in number to thofe of the known plants, which, upon the moft moderate computation, cannot be lefs than fixteen thoufand. 'I he feveral kinds found at the roots of particular plants 'may be diftinguifhed each by the particular name of the plant they feed on, while thofe found under the turf, and feeding on the roots of grafs, may be called Earth pucerons.

EARTHQUAKE [Cyc!.)— In the philofophical tranfaclions, N°. 462. Sect. 11. we have a journal of the fhocks of Earth-