EAR 



ARTH is the principal matter whereof our 

 globe confifts ; the charafter of which, accord- 

 ing to Dr. Boerhaave, is, that it is a foflil body, 

 neither diflbluble by fire, water, nor air ; that 

 it is infipid and tranfparent -, more fufible than ftone ; 

 ftill friable, and containing ufually afliare of fatnefs. 

 There is no fuch thing as a ftriclly fimple earth. 

 Mr. Boyle fays, that it doth not appear, that nature, 

 any more than art, affords an elementary earth -, at 

 leaft, fome which appear of the fimpleft forts are 

 found, upon examination, to have qualities not af- 

 cribed to pure earth. 



Of fuch earths fome are fimple and immutable, as 

 chalk, pumice, and rotten flone ; others compound 

 and fatty -, of which kind are all boles, red, white, 

 and brown ; fullers earth, and divers kinds of medi- 

 cinal earths, as the Crcdca, Hungarica, Lemnian 

 earth, and others. 



Which earth are all refolvable into oil, a little acid 

 fait, &c. and a calx, which is the.bafis, or the earth 

 properly fo called. 



Sand is by naturalifts generally ranked as a fpecies of 

 earth, though not very properly ; in that fands, 

 ftriftly fpeaking, are a fort of cryftals, or little tranf- 

 parent pebbles, and are calcinable; and, by the addi- 

 - tion of a fixed alkaline fait, fufible and convertible 

 : into glafs, . 



■ The fat earth is rendered fertile by the means of 

 fand, and becomes fit to feed and nourifti vegetables, 

 &c. for pure earth is liable to coalefce into a hard co- 

 herent mafs, as in clay ; and earth thus embodied, 

 and as it were glued together, would be very unfit 

 for the nouriflmient of plants. ' .. ' 



But if hard fand, i. e. cryftals, which are indifiblu- 

 ble in water, and ftill retain the fame figure, be in- 



termixed with fuch earth, they will keep the pores of 

 the earth open, and the earth itfelf loofe and incom- 

 pa£l, and by that means give room for the juices to 

 move, afcend, &c. and for plants to be nourifned 

 thereby. 



Thus a vegetable, being planted either in the fand 

 alone, or in the fat glebe and earth alone, receives 

 no growth or increment, but is either ftarved or fuf- 

 focated ; but mix the two, and the mafs becomes 

 fertile. 



In effeft, by means of fand the earth is rendered, 

 in fome mxafurc, organical j pores ^nd interftices be- 

 ing hereby maintained or preferved, fomething analo- 

 gous to vefTels is effefted, by which the jujices of the 

 earth maybe conveyed, prepared, digefted, circulat- 

 ed, and at length excerned and thrown off in the 

 roots of plants. 



The earth is made up of two parts ; the firft the con- 

 taining part, i. e, the body, bed, or couch : the fe- 

 cond the part contained, and thofe are the nitrous or 

 fulphureous particles, or prolific falts. The firft is a 

 lifelefs inanimate mafs, and is only the receptacle of 

 the other ; for the earth, confidered fimply, and ab- 

 ftrafted from the before-mentioned nitrous and prolific 

 falts, is a lifelefs, dead, and inanimate mafs -, but by 

 the co-operation of water, fun, and air, is put into 

 motion, and promotes the work of vegetation : but 

 if it were ftript of thofe prolific falts and fpirituous 

 particles, would produce no manner of plant, herb, 

 &c. that fhould be planted or fown in it. 



EAR 



Thefe nitrous particles, or prolific falts, are of va- 

 rious and different qualities ^ and according as die 

 earth is more or lefs ftored with all or fome of them, 

 it is more or lefs productive ; and according as it 

 abounds with fome of them more than others, differ- 

 ing froin one another in contexture, it conftitutes die 

 different fpecies or kinds of foils adapted to the pro- 

 pagation of different plants, the pores of wliofe roots 

 are formed to receive, and whofe nature is to attraft, 

 thofe falts that are congenial to them. 

 Some diftinguifh earths into three claffes, fand, 

 loam, and clay, as thofe upon one or other of which 

 all others do in fome refpefts depend. 

 Gravel, and all the open foils, till the loam is come 

 at, are of thefandy kind. 



Thofe binding earths from the loam downwards, 

 till the ftiffneis of chalk may be come at, may be 

 reckoned of the clay kind. 



All thefe forts of earth have a little tendency to ve- 

 getation, and have their falts proper for it, but in a 

 different proportion ; as a peck of clay may probably 

 have double the quantity of falts in it that a peck of 

 loam has, and a peck of loam may have fix times 

 the quantity of falts that a peck of fand has. 

 Loam... Some call the fuperficial earth that we meet 

 with in England by this name, without having regard 

 to what proportion of fand and clay it contains : others 

 again call that earth loam, that inclines more to clay 

 than fand. Some by loam mean that fort of earth 

 that equally partakes of fand and clay, being a me- 

 dium between fand and clay, which they call modier 

 earth ; but the true definition of loam is, that fort 

 of earth which is fat and flippery, not of fo clofea 

 texture as clay, nor too loofe and fandy, but of a 

 middle nature between them, and is eafily diffolved 



This 





-K\ 



by froft, and gentle or eafy to be wrought, 

 is one of the beft foik for moft efculent plants and 

 roots. 



This mother earth, they fay, may be in colour either 

 black or yellow, and of which of thefe colours foever 

 it be, plants of moft forts will grow in it. 

 Sand and clay likewife produce certain plants, which 

 are natural to each of them, and confequendy will 

 thrive better in them than in any other foil. 

 But fand is apt to precipitate thofe plants that are 

 fet in it, earlier than clay, and will caufe them to ger- 

 minate near a month fooner than thofe that grow in 

 clay, and that for this reafon, becaufe the falts which ' 

 are in fand, are liable to be put in motion by the 

 leaft approach of the warmth of the fun ; but as fand 

 is quick in the operation, the falts are foon exliakd 

 and fpent. 



Clay. The pores of clay are more clofely compared 

 together, and do not fo eafily give out thofe falts that 

 are contained in it •, nor can the fibres of ever\' tender 

 plant make their way through it in queft of their pro- 

 per nutriment. 



But if the parts of the clay be opened, by diggii^g 

 and breaking it into fmall particles, and thofe parts 

 be kept open by a mixture of fome fliarp fand, or iovd^ 

 other body of the like quality, the effefts of its vi- 

 gour will plainly appear. 



Some diftinguifti the feveral temperaments of the 

 earth either into a light, fandy, or loofe contexture, 



or into thofe of a ftiff. clayey, or dole one, either oi 



which 



y 



