E ARTH is the principal matter whereof our 
globe confifts 5 the character of which, accord- 
ing to Dr. Boerhaave, is, that it is a foflil body, 
neither diffoluble by fire, water, nor air ; that 
it is infipid and tranfparent •, more fufible than ftone ; 
ftill friable, and containing ufually a fiiare of fatnefs. 
There is no fuch thing as a ftridtly 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 ftone •, 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 Cretica, 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, 
ftridtly fpeaking, are a fort of cryftals, or little tranf- 
parent pebbles, and are calcinable j 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 nourifh 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 nourifhment of plants. 
But if hard fand, i. e. cryftals, which are indiffolu- 
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- 
padt, and by that means give room for the juices to 
move, afcend, &c. and for plants to be nourifhed 
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 meafure, organical ; pores and interftices be- 
ing hereby maintained or prelerved, fomething analo- 
gous to veffels is effected, by which the juices of the 
earth may be 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 3 
lifelefs inanimate mafs, and is only the receptacle of 
the other *, for the earth, confidered fimply, and ab- 
ftradted 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 ftiould be planted or fown in it. 
Thefe nitrous particles, or prolific falts, are of va- 
rious and different qualities ; and according as the 
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 from one another in contexture, it conftitutes the 
different fpecies or kinds of foils adapted to the pro- 
pagation of different plants, the pores of whofe roots 
are formed to receive, and whofe nature is to attraft, 
thofe falts that are congenial to them. 
Some diftinguiih earths into three claffes, fand, 
loam, and clay, as thofe upon one or other of which 
all others do in fome refpedts depend. 
Gravel, and all the open foils, till the loam is come 
at, are of the fandy kind. 
Thofe binding earths from the loam downwards, 
till the ftiffnefs 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 land and clay, which they call mother 
earth ; but the true definition of loam is, that fort 
of earth which is fat and flippery, not of fo clofe a 
texture as clay, nor too loofe and fandy, but of a 
middle nature between them, and is eafily diffolved 
by froft, and gentle or eafy to be wrought. This 
is one of the belt foils 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 confequently 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 exhaled 
and fpent. 
Clay. The pores of clay are more clofely compacted 
together, and do not fo eafily give out thofe falts that 
are contained in it ; nor can the fibres of every tender 
plant make their way through it in queft of their pro- 
per nutriment. 
But if the parts of the clay be opened, by digging 
and , breaking it into fmall particles, and thofe parts 
be kept open by a mixture of fome fnarp fand, or fome 
other body of the like quality, the effefts of its vi- 
gour will plainly appear. 
Some diftinguifn the feveral temperaments of the 
earth either into a light, fandy, or loofe contexture, 
or into thofe of a ftiff, clayey, or clofe one, either of 
which 
