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[ the end of a stick, is pushed forward under the Planter upon thip roots of the fmall weeds, in fuch a manner as to cut them up a little below the furface of the foil, and will do more execution at one fhove than can be done at three ftrokes of the common hoe: but there is yet another practice of the horse-hoe plough, whereby all weeds growing in rows between beans and peaíe, are extirpated with incredible eafe and expedition. It is a very fimple machine, drawn by one or two horses, confifting of a pair of low wheels turning upon a common axis; from whence two fquare irons are let down at equal distances, and triangular hoes made at the ends, the points of the triangles being placed forward, and fo fixed as to cut all weeds an inch below the furface, in the fame manner as the Dutch garden hoe above-mentioned. By this machine a man and a boy, with two horses or mules, will clear perfectly all the spaces of a field of ten acres in two days, and may be of admirable ufe in all loofe and dry foils in the fugar-iflands: for while two horses or mules draw in the space before each other, the wheels país on the outfide of each row of canes, without doing the leaft injury, while the plough-holder attends to his bufinefs. In ftiff foils which require draining, neither the horse-hoe plough nor the Dutch hoe can be proper; or any other inftrument fo effectual as the fpade ufed in the manner above hinted, where the ftaple is deep.

ship.

21 ]
confiderable advantage; and yet it is the least of all at- Planter
tending this method of culture: for, by leaving these
fpaces, the canes will have both more air and fun by
have large room for expanfion, and confequently, by
hoe-ploughing them, the roots of each double row will
gaining more nutriment, will grow more luxuriantly:
by these spaces the canes may be cleaned from the blast
with much more eafe and convenience; and will ferve
as proper beds to plant great corn, without the least in-
jury to the canes; as well as to contain the trash taken
off the land, where, by rotting, and being hoe-ploughed
into the foil, it will wonderfully enrich it, and will
fit it to be planted immediately after the canes in the
neighbouring double rows are cut down. Befides all
ternate double rows with equal spaces, the canes, when
thefe admirable advantages of planting the land in al-
at full age, may be eafily ftripped of their trash, and by
that means the juice rendered fo mature as to yield dou-
ble the produce, and much better fugars than unftripped
canes. This method of culture may be recommended for
all kinds of foil: for as by this practice the rank luxu
riant canes will be more matured, fo the poor foils will
be rendered more fruitful; and as the roots of the canes
which expand into thefe fpaces will be kept moift by
being covered with rotten trafh, fo they must bear dry
lands which require draining by furrows, the alternate
weather much longer in the burning foils. In those low
double rows and spaces must be made cross the ridges; by
which means thofe spaces, being hoe-ploughed from the
ftate of roundness. By this method of planting, the
centre to the fides, will be always preferved in a proper
canes may be fo well ripened as to yield double the
quantity of fugar of canes planted in the clofe manner;
which faves half the labour of cartage, half the time of
grinding and boiling, and half the fuel, befides yielding
finer fugar.

But where the ftaple of land is fhallow, care muft
be taken not to dig much below it, according to the uni-
verfal opinion of all the best writers, fupported by the
experience of 100 years Yet fome good planters are
ftiff clay far
fallen into the contrary practice, and dig up
below the staple. This, Mr Martin fays, was done in
his own lands, during his abfence, by injudiciously
ploughing below the ftaple; and fo injured the foil, that
all the arts of culture for many years hardly retrieved its
former fertility. Indeed, where the ftaple is fhallow,
upon a fat clay, the turning up a little of it at a time,
from the bottom of the cane-holes, and mixing it with
rich hot dung, made of marle, or fandy mould, which may
take off its cohefive quality, will in due time, and by
long fallow, convert it into good foil: but if ftiff clay
be turned up, without any fuch mixture, in large quan-
tities, it will infallibly disappoint the operator's hopes:
for though folid clay will moulder, by expofure, to a
feeming fine earth, yet it will return to its primitive state
very foon after being wet, and covered from the external
air, if not divided, as above fuggested.

After all, the common horfe-hoeing plough drawn by
two mules in a line before each other, or the hand-hoe in
common ufe, will anfwer the purpose very well, where
the lands are planted in Mr Tull's method; that is, where
the spaces are equal to the land planted, in the following

manner.

Suppofe fix feet planted in two rows of canes, and fix feet of land left as a space unplanted; and fo a whole piece of land, planted in alternate double rows (F), with equal spaces, may be hoe-ploughed with eafe, as before hinted; and that at any time during the growth of canes, when it is moft convenient to the planter, which is a

4

Yet, how well foever the method of planting in single or double alternate rows has fucceeded in the loofe and tice in ftiff lands that are thrown into round or flat ftiff foils, experience has shown that it is a wrong pracridges: for thefe being moft apt to crack, the fun-beams penetrate foon to the cane-roots, ftop their growth, and have an ill influence upon the fugar. It is therefore ad-vifable to plant fuch lands full, but in large holes, of are cut, to dig out one, and leave two rows ftanding, feet, by 5 feet towards the banks: after the plant-canes furrows till almoft rotten: for if the trash is drawn uphoe-ploughing the spaces after turning all the trash into on the hoe-ploughed fpaces, they will hardly ever moulan infallible proof from experience of how little advander, at least not till the trash is quite rotten. This is tage trafh is to the foil, unless it be in great droughts, fpects, it prevents that joint operation of the fun and to keep out the intense fun-beams: for, in all other reair in mouldering and fructifying the foil, as has been proved by repeated experiments.

But in flat ftiff foils that are properly drained by round-ridging, no culture prevents cracking fo effectually as hoe-ploughing into them a quantity of loofe marle, of which that of a chocolate or of a yellow colour is

beft;

(F) In ftiff lands, the fingle alternate rows of four feet diftance, as preventive of much labour in weeding, aree found beft; and alfo yield more fugar by the acre; and are lefs apt to be affected by drought.

Planter beft; and it will be ftill much better, by lying upon the ship. land, in fmall heaps, or in cane-holes, for fome time, to imbibe the vegetative powers of the air before it is intimately mixed with the foil.

As to the manner of planting canes, the general practice of allowing four feet by five to an hole, and two fresh (G) plants, is found by common experience to be right and good in alternate rows. But the following precautions are neceffary to be obferved. First, let all the cane-rows run east and weft, that the trade-wind may pafs freely through them; because air and funshine are as conducive to the growth and maturation of fugarcanes as of any other vegetable. Secondly, let not any acceffion of mould be drawn into hills round the young canes, except where water ftagnates (H); because the fibres which run horizontally, and near the furfaces are much broken and fpoiled by that practice. Thirdly, let the fugar-canes be cut at their full maturity; which, in a dry loofe foil, is generally at the end of 14 or 15 months after being planted; but in cold clay-foils, not till 16 or 17 months. Fourthly, as the cane-rows run eaft and weft in as proper a direction as poffible for cartage to the fugar work, fo canes must be cut the contrary way if the planter expects any great produce from his rattoons: for by beginning to cut canes at the part of his field most remote from the works, the carts cannot often pass over the fame tract, and confequently the cane-ftools cannot be injured, more especially if he takes due care to cut the canes very close to their roots; for, by leaving a long ftub (which muft perifh) the caneftools are much injured. It may be objected to the practice of the cutting canes tranfverfely to the rows, that the negroes labour will not be fo equally divided: but let every man confider both fides of the queftion, and be determined by his own experience; and then he will be convinced, that it matters very little which way he cuts straight standing canes; but in cafes where the fugar-canes lean, or are lodged by preceding high winds, it is a point of great importance to place the labourers fo as to cut the canes first at the roots, and then, drawing them, cut off the tops: for thus by two ftrokes each cane will be cut; and twice the quantity cut in the fame time, and by the fame hands, more than by cutting in any other direction. In round-ridged land, it is proper to cut canes in the fame direction of the ridges, throwing the tops and trash into the furrows to render the cartage eafy, and to preferve the ridges in their proper form.

It is almost needlefs to fuggeft the expediency of planning the cane-pieces of a plantation in exact fquares, fo that the intervals may interfect at right angles; fince fuch regularity is not only more beautiful, more fafe in cafe of accidental fires, and a better difpofition of the whole for dividing and planting one third or fourth part of a plantation every year, but also much eafier guarded by a few watchmen: for one of thefe walking in a line

from east to west, and the other from north to fouth, Plantin look through every avenue, where the most fubtle thief Planting. cannot escape the watchful eye. And if the intervals furrounding the boundary of a regular plantation be made 24 feet wide, the proprietor will receive ample recompenfe for fo much land, by the fecurity of his canes from fires kindled in the neighbourhood, and by planting all that land in plantain-trees, which may at once yield food and fhade to the watchmen, who by that means can have no excufe for abfence from their proper stations. But as fuel grows very fcarce in most of our iflands, it is alfo expedient to plant a logwood or flower fence in all the boundaries of every plantation, which, being cut every year, will furnish good store of faggots. Logwood makes the ftrongest and quickest of all fences, and agrees with every foil: the cuttings make excellent oven-fuel.

So much for the general operations of planterfhip, according to the approved directions of Mr Martin. For the particular cultivation of the fugar-canes, the extraction of the fugar, and the diftillation of rum, fee the articles SACCHARUM, SUGAR, and RUM.

PLANTIN (Chriftopher), a celebrated printer, was born near Tours in 33, and bred to an art which he carried to the highest degree of perfection. He went and fettled at Antwerp; and there erected a printing office, which was confidered not only as the chief ornament of the town, but as one of the most extraordinary edifices in Europe. A great number of ancient authors were printed here; and these editions were valued not only for the beauty of the characters, but also for the correctnefs of the text, with regard to which Plantin was fo very nice, that he procured the most learned men to be correctors of his prefs. He got immenfe riches by his profeffion; which, however, he did not hoard up, but spent like a gentleman. He died in 198, aged 65 years; and left a moft fumptuous and valuable library to his grandfon Balthafar.

PLANTING, in agriculture and gardening, is fetting a tree or plant, taken from its proper place, in a new hole or pit; throwing fresh earth over its root, and filling up the hole to the level of the furface of the ground.

The first thing in planting is to prepare the ground before the trees or plants are taken out of the earth, that they may remain out of the ground as short a time as poffible; and the next is, to take up the trees or plants, in order to their being tranfplanted. In taking up the trees, carefully dig away the earth round the roots, fo as to come at their feveral parts to cut them off; for if they are torn out of the ground without care, the roots will be broken and bruised, to the great injury of the trees. When you have taken them up, the next thing is to prepare them for planting by pruning the roots and heads. And firft, as to the roots; all the fmall fibres are to be cut off, as near to the place from whence they

(G) It is an odd fancy that ftale plants grow beft, when both reafon and experience vouch that the most fucculent plants are beft: one good plant in the centre of a large hole is fufficient when the land is full holed.

(H) The stagnation of water in pools (ufual in ft ff level lands) is the moft injurious circumftance attending it; for that, by long duration, will convert the finest mould into ftiff clay. The proprietor of fuch a foil must therefore grudge no labour to drain it well; and yet by such easy gradation as to prevent the mould from being washed away by great floods, in case the under ftratum be a loam.

Planting. they are produced as may be, except they are to be replanted immediately after they are taken up. Then prune off all the bruifed or broken roots, all fuch as are irregular and cross each other, and all downright roots, efpecially in fruit-trees: fhorten the larger roots in proportion to the age, the strength, and nature of the tree; obferving that the walnut, mulberry, and fome other tender-rooted kinds fhould not be pruned fo clofe as the more hardy forts of fruit and foreft trees: in young fruit-trees, fuch as pears, apples, plums, peaches, &c. that are one year old from the time of their budding or grafting, the roots may be left only about eight or nine inches long; but in older trees, they must be left of a much greater length: but this is only to be understood of the larger roots; for the fmall ones must be chiefly cut quite out, or pruned very fhort. The next thing is the pruning of their heads, which must be differently performed in different trees; and the defign of the trees must also be confidered. Thus, if they are defigned for walls or efpaliers, it is beft to plant them with the greateft part of their heads, which fhould remain on till they begin to fhoot in the fpring, when they must be cut down to five or fix eyes, at the fame time taking care not to disturb the roots. But if the trees are defigned for ftandards, you should prune off all the fmall branches close to the place where they are produced, as alfo the irregular ones which crofs each other; and after having difplaced these branches, you should also cut off all fuch parts of branches as have by any accident been broken or wounded; but by no means cut off the main leading fhoots which are neceffary to attract the fap from the root, and thereby promote the growth of the tree. Having thus prepared the trees for planting, you must now proceed to place them in the earth: but firft, if the trees have been long out of the ground, fo that the fibres of the roots are dried, place them eight or ten hours in water, before they are planted, with their heads erect, and the roots only immersed therein; which will fwell the dried veffels of the roots, and prepare them to imbibe nourishment from the earth. In planting them, great regard fhould be had to the nature of the foil: for if that be cold and moist, the trees fhould be planted very shallow; and if it be a hard rock or gravel, it will be better to raise a hill of earth where each tree is to be planted, than to dig into the rock or gravel, and fill it up with earth, as is too often practifed, by which means the trees are planted as it were in a tub, and have but little room to extend their roots. The next thing to be obferved is, to place the trees in the hole in fuch a manner that the roots may be about the fame depth in the ground as before they were taken up; then break the earth fine with a spade, and scatter it into the hole, fo that it may fall in between every root, that there may be no hollowness in the earth: then having filled up the hole, gently tread down the earth with your feet, but do not make it too hard; which is a great fault, especially if the ground be strong or wet. Having thus planted the trees, they fhould be faftened to ftakes driven into the ground to prevent their being difplaced by the wind, and fome mulch laid upon the furface of the ground about their roots; as to fuch as are planted against walls, their roots fhould be placed about five or fix inches from the wall, to which their heads fhould be mailed to prevent their being blown up by the wind. The feafons for planting are various, according to the diffe

rent forts of trees, or the foil in which they are planted. Plantings. For the trees whofe leaves fall off in winter, the best time is the beginning of October, provided the foil be dry; but if it be a very wet foil, it is better to defer it till the latter end of February, or the beginning of March: and for many kinds of evergreens, the beginning of April is by far the beft feafon; though they may be fafely removed at midfummer, provided they are not to be carried very far; but should always make choice of a cloudy wet feafon.

In the fecond volume of the papers, &c. of the Bath Society there is a letter on planting wafte grounds. The gentleman who writes it informs us, that in the county of Norfolk, where he refides, there were about 60 or 70 years ago vast tracts of uncultivated ground, which were then thought totally barren. "The weftern parts of it (fays he) abounded with fand of fo light a texture, that they were carried about by every wind; and in many places the fands were fo loofe that no grafs could grow upon them. Art and industry, however, have now fo altered the face of this once Arabian defert, that it wears a very different appearance. Most of these tracts are either planted or rendered very good corn-land and sheepwalks.

"About 30 years fince, the fides of many of our little fand-hills were fown with the feeds of French furze, and when a wet feafon followed, they fucceeded very well, and grew fo faft, that once in three or four years they are cut for fuel, and fell at a good price at Thetford, Brandon, Harling, Swaffham, and places adjacent. This excited fome public fpirited gentlemen, among whom was the late Mr Buxton of Shadwell-Lodge, near Thetford, to attempt the planting of Scotch and fpruce firs, and other hardy forest-trees. At first they found fome difficulty from the extreme loofenefs of the fand. But as there is in all this part of the country fine white and yellow marle, at about three feet depth below the fand, they very judiciously thought that incorporating it with the fand in the holes where their young trees. were planted, would infure fuccefs; nor were they difappointed. The method fucceeded beyond expectation; the plantations throve exceedingly, and the roots foon reached below the fand, after which they were out of danger. This excited them to further attempts.

"On the spots where they intended to raise new plantations from feeds and acorns, they laid on a thick coat. of marle and clay, which after being rough fpread, and lying a winter in that ftate, was made fine, and ploughed in just before planting. By thefe means the foil be came fixed, and in a little time covered with grafs and herbage; fo that there are now vaft plantations of firs, oak, and foreft-trees, in the moft healthy and vigorous ftate, where within my memory ten acres of land would: not maintain a single sheep three months.

"But the benefit of plantations, whether of fhrubs, copfe, or trees, is not confined to the immediate advan tage, or even the future value of the wood. By annually fhedding a great number of leaves, which the winds difperfe, and the rains wafh into the foil, it is confiderably improved; and whenever fuch copfes have been: stubbed up, the ground (however unfruitful before plant-. ing) has thereby been fo enriched as to bear excellent crops for many years, without the additional help of manure. How much land-owners are interested in planting waste or barren spots, I need not mention; and no

Plating.

it.

Planting thing but a degree of indolence or ignorance unpardonable in this enlightened age could induce them to neglect "Nature has furnished us with plants, trees, and fhrubs, adapted to almoft every foil and fituation; and as the laws of vegetation are now much better understood than formerly, it is a reproach to those whofe practice does not keep pace with their knowledge in making the beft ufe of her bounty. Let no man repine and fay the land is barren; for those fpots which appear to be fo, owe that appearance to human negligence. Induftry and art might foon render an eighth part of this kingdom nearly as valuable as the reft, which now remains in a ftate unprofitable to the owners, and difgraceful to the community."

Reverfe PLANTING, a method of planting in which the natural pofition of the plant or fhoot is inverted; the branches being fet into the earth, and the root reared into the air. Dr Agricola mentions this monitrous method of planting, which he found to fuccced very well in most or all forts of fruit-trees, timber-trees, &c. Bradley affirms, that he has feen a lime-tree in Holland growing with its first roots in the air, which had shot out branches in great plenty, at the fame time that its first branches produced roots and fed the tree. Mr Fairchild of Hoxton has practifed the fame with us, and gives the following directions for performing it: Make choice of a young tree of one shoot, of alder, elm, willow, or any other tree that easily takes root by laying; bend the fhoot gently down into the earth, and fo let it remain until it has taken root. Then dig about the first root, and raise it gently out of the ground, till the ftem be nearly upright, and itake it up. Then prune the roots, now erected in the air, from the bruifes and wounds they received in being dug up; and anoint the pruned parts with a compofition of two ounces of turpentine, four ounces of tallow, and four ounces of bees wax, melted together, and applied pretty warm. After wards prune off all the buds or fhoots that are upon the ftem, and dress the wounds with the fame compofition, to prevent any collateral shootings, that might fpoil the beauty of the ftem.

PLANUDES (Maximus), a Greek monk of Conftantinople, towards the end of the 14th century, who published a collection of epigrams intitled Anthologia; a Greek tranflation of Ovid's Metamorphofes; a Life of Æfop, which is rather a romance than a hiftory; and fome other works. We know nothing more of him, than that he fuffered fome perfecution on account of his

attachment to the Latin church.

PLASHING of HEDGES, is an operation thought by fome perfons to promote the growth and continuance of old hedges; but whether the fact be fo or not will admit of fome difpute. See HEDGES, no 29, 37, &c.

It is performed in this manner: The old ftubs muft he cut off, &c. within two or three inches of the ground; and the best and longeft of the middle-fized fhoots muft be left to lay down. Some of the strongest of these muft alfo be left to answer the purpose of stakes. Thefe are to be cut off to the height at which the hedge is intended to be left; and they are to ftand at ten feet diftance one from another: when there are not proper fhoots for these at the due diftances, their places must he fupplied with common ftakes of dead wood. The

Plafter.

hedge is to be first thinned, by cutting away all Lut Plafhing thofe fhoots which are intended to be ufed either as ftakes, or the other work of the plafhing: the ditch is to be cleaned out with the fpade; and it must be now dug as at firft, with floping fides each way; and when there is any cavity on the bank on which the hedge grows, or the earth has been. wafhed away from the roots of the fhrubs, it is to be made good by facing it, as they exprefs it, with the mould dug from the upper part of the ditch: all the rest of the earth dug out of the ditch is to be laid upon the top of the bank and the owner fhould look carefully into it that this be done; for the workmen, to fpare theinfelves trouble, are apt to throw as much as they can upon the face of the bank; which being by this means overloaded, is foon washed off into the ditch again, and a very great part of the work undone; whereas what is laid on the top of the bank always remains there, and makes a good fence of an indifferent hedge.

In the plafhing the quick, two extremes are to be avoided; these are, the laying it too low, and the laying it too thick. The latter makes the fap run all into the fhoots, and leaves the plashes without fufficient nourifhment; which, with the thickness of the hedge, finally kills them. The other extreme of laying them too high, is equally to be avoided; for this carries up all the nourishment into the plafhes, and fo makes the foots fmall and weak at the bottom, and confequently the hedge thin. This is a common error in the north of England. The beft hedges made anywhere in England are thofe in Hertfordshire; for they are plafhed in a middle way between the two extremes, and the cattle are by that prevented both from cropping the young fhoots, and from going through; and a new and vigorous hedge foon forms itself.

When the shoot is bent down that is intended to be plafhed, it must be cut half way through with the bill: the cut muft be given floping, fomewhat downwards, and then it is to be wound about the stakes, and after this its fuperfluous branches are to be cut off as they ftand out at the fides of the hedge. If for the fir year or two, the field where a new hedge is made can he plough. ed, it will thrive the better for it; but if the ftubs are very old, it is beft to cut them quite down, and to fecure them with good dead hedges on both fides, till the fhoots are grown up from them ftrong enough to plash; and wherever void spaces are feen, new fets are to be planted to fill them up. A new hedge raised from fets in the common way, generally requires plathing in about eight or nine years after.

PLASSEY, is a grove near the city of Muxadab in India, famous for a battle fought between the English under Lord Clive and the native Hindoos under the Nabob Surajah Dowlah. The British ariny confifted of about 3200 men, of whom the Europeans did not exceed yoo; while that of the Nabob confifted of 50,000 foot, and 18,000 horfe. Notwithstanding this great difproportion, however, Lord Clive effectually routed the Nabob and his forces, with the lofs of 3 Europeans and 26 Seapoys killed, and 5 Europeans and 40 Seapoys wounded. The Nabob's lofs was estimated at about 200 men, befides oxen and elephants. See CLIVE.

PLASTER, or EMPLASTER, in pharmacy, an external application of a harder confiftence than an oint

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li.

[ 23 ] PLA Plafier. ment; to be fpread, according to the different circum. ftances of the wound, place, or patient, either upon nen or leather. See PHARMACY, " 613-635. PLASTER, or Plaifter, in building, à compofition of lime, fometimes with fand, &c. to parget, or cover the nudities of a building. See PARGETING and STUC

CO.

PLASTER of Paris, a preparation of feveral fpecies of gypfum dug near Mount Maitre, a village in the neighSee ALABAS bourhood of Paris; whence the name. TER, GYPSUM, and CHEMISTRY, no 635, &c. The beft fort is hard, white, fhining, and marbly; known by the name of plafter-flone or barget of Mount Maitre. It will neither give fire with steel, nor ferment with aquafortis; but very freely and readily calcines in the fire into a fine plafter, the ufe of which in building and cafting ftatues is well known.

The method of reprefenting a face truly in plafter of Paris is this: The perfon whofe figure is defigned is laid on his back, with any convenient thing to keep off the hair. Into each noftril is conveyed a conical piece of ftiff paper, open at both ends, to allow of refpiration. These tubes being anointed with oil, are fupported by the hand of an affiftant; then the face is lightly oiled over, and the eyes being kept fhut, alabafter fresh calcined, and tempered to a thinnish confiftence with water, is by fpoonfuls nimbly thrown all over the face, till it lies near the thickness of an inch. This matter grows fenfibly hot, and in about a quarter of an hour hardens into a kind of ftony concretion; which being gently taken off, reprefents, on its concave furface, the miIn this a head of nuteft part of the original face. good clay may be moulded, and therein the eyes are to be opened, and other neceffary amendments made. This fecond face being anointed with oil, a fecond mould of calcined alabaster is made, confifting of two parts joined lengthwife along the ridge of the nofe; and herein may be caft, with the fame matter, a face extremely like the original.

If finely powdered alabafter, or plafter of Paris, be
put into a bafon over a fire, it will, when hot, affume
the appearance of a fluid, by rolling in waves, yielding
to the touch, fteaming, &c. all which properties it again
lofes on the departure of the heat; and being thrown
upon paper, will not at all wet it, but immediately dif-
cover itfelf to be as motionlefs as before it was fet over
the fire; whereby it appears, that a heap of fuch little
bodies, as are neither fpherical nor otherwife regularly
fhaped, nor fmall enough to be below the difcernment
of the eye, may, without fufion, be made fluid, barely
by a fufficiently ftrong and various agitation of the par-
ticles which compofe it; and moreover lofe its fluidity
immediately upon the ceffation thereof.

Two or three fpoonfuls of burnt alabaster, mixed up
thin with water, in a fhort time coagulate, at the bot-
tom of a veffel full of water, into a hard lump, notwith-
standing the water that furrounded it. Artificers ob-
ferve, that the coagulating property of burnt alabafter
will be very much impaired or loft, if the powder be
kept too long, efpecially if in the open air, before it is
made ufe of; and when it hath been once tempered
with water, and suffered to grow hard, they cannot, by
any burning or powdering of it again, make it fervice-
able for their purpose as before.
VOL. XV. Part I.

PLA

This matter, when wrought into veffels, &e. is fill Plaker.
of fo loafe and spongy a texture, that the air has eafy
paffage through it. Mr Boyle gives an account, among
his experiments with the air-pump, of his preparing a
tube of this plafter, closed at one end and open at the
other; and on applying the open end to the cement, as
is ufually done with the receivers, it was found utterly
impoffible to exhauft all the air out of it; for fresh air
from without preffed in as faft as the other, or internal
air, was exhausted, though the fides of the tube were of
a confiderable thickness. A tube of iron was then put
on the engine; fo that being filled with water, the tube
of plafter of Paris was covered with it; and on ufing
the pump, it was immediately feen, that the water paffed
through into it as eafily as the air had done, when that
was the ambient fluid. After this, trying it with Ve-
nice turpentine instead of water, the thing fucceeded
very well; and the tube might be perfectly exhausted,
and would remain in that ftate feveral hours. After
this, on pouring fome hot oil upon the turpentine, the
cafe was much altered; for the turpentine melting with
this, that became a thinner fluid, and in this ftate ca-
pable of paffing like water into the pores of the plafter.
On taking away the tube after this, it was remarkable
that the turpentine, which had pervaded and filled its
pores, rendered it tranfparent, in the manner that wa
In this manner, the weight of air, under pro-
ter gives tranfparency to that fingular stone called oculus
mundi.
per management, will be capable of making feveral forts
of glues penetrate plafter of Paris; and not only this,
but baked earth, wood, and all other bodies, porous
enough to admit water on this occafion.

Plafter of Paris is used as a manure in Pennfylvania, as
we find mentioned in a letter from a gentleman in that
country inferted in the 5th volume of the Bath Society Pa-
pers, and which we fhall infert here for the fatisfaction
and information of our agricultural readers. "The beft
kind is imported from hills in the vicinity of Paris: it is
brought down the Seine, and exported from Havre de
Grace. I am informed there are large beds of it in the
Bay of Fundy, fome of which I have feen nearly as good
as that from France; nevertheless several cargoes brought
from thence to Philadelphia have been used without effect.
It is probable this was taken from the top of the ground,
and by the influence of the fun and atmosphere difpoffeffed
of the qualities neceffary for the purposes of vegetation.
The lumps compofed of flat fhining fpecula are preferred
to thofe which are formed of round particles like fand: the
fimple method of finding out the quality is to pulverize
fome, and put it dry into an iron pot over the fire, when
that which is good will foon boil, and great quantities
of the fixed air efcape by ebullition. It is pulverized
by firft putting it in a ftamping-mill. The finer its pul-
verization the better, as it will thereby be more gene
rally diffused.

"It is beft to fow it in a wet day. The most ap-
No
proved quantity for grafs is fix bufhels per acre.
art is required in fowing it more than making the dif
tribution as equal as poffible on the fward of grafs. It
operates altogether as a top manure, and therefore fhould
not be put on in the fpring until the principal frofts are
over and vegetation hath begun. The general time for
Its effects will gene-
fowing with us is in April, May, June, July, Auguft,
and even as late as September.
rally

D

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