haftened with an army to his affiftance, and through mifinformation, flew her own hufband; whether any human bones lie buried there, future time muft discover.

For manufacturing their faltpetre, they make choice of a place not far from a spot rich enough in nitre to keep them continually at work for at leaft a whole fummer; and befides, fuch as can fupply them fufficiently with water and wood at an eafy expence. The utenfils they employ, are called by one name maydan, and confist of the following articles; 1. A large copper boiler, containing about 60 amphors, of 6 gallons, or about 54 pounds of water each.

2. One hundred wooden tubs or fats, open on the top, with a hole bored near the bottom, which may be ftopped occafionally; each of thefe holds a carr of earth, or about 4 or 5 amphors.

3. Two very large cafks of about 100 amphors each.

4. Wide troughs or coolers to the number of 32, holding an amphor each, or fomewhat more, in which the cryftallization is to be performed.

5. A fufficient number of amphors for fetching water.

A pit is dug in the ground, of depth fufficient for erecting a furnace or fire-place at the bottom, and receiving the boiler fet in with bricks over it, with its brim on a level with the furface, over which brim is conftructed a circular covering or border of wood about eight inches high, and this lined with lute to keep the ley from boiling over. The two great cafks are placed at a fmall diftance, being deftined to receive

the ley, which is conveyed into them by hand-fcoops.

The nitrous earth is firft of all beat to a coarse powder with iron fpades, and cleared of ftones and other hard fubftances, laid lightly in heaps, and then brought to the furnace. If it be very rich in nitre (indicated either by its fatness, or its downy efflorefcence) they mix with it fome of a poorer fort, in equal quantity, but very black and old: this is, in the language of the chemifts, with an animal earth they combine one that is purely vegetable. Laft of all, they add afhes, to the amount of about a fifth part of the whole, more or lefs, as beft fuits their purpose, and mix them together. The afhes they commonly make use of are of the afh, which they have in great plenty. If they have a quantity of urine at hand, they throw it in, but never any quick lime. Thus they prepare a fuitable ftock of earth at the beginning of the fummer, and continue to do fo as long as is neceffary, so as never to be in want of a fresh supply. Some are fo provident as to prepare beforehand a' quantity fufficient to laft them through the whole course of the enfuing fummer but the usual practice is to bring the earth, as foon as prepared, to the furnace, which is done in the following manner.

Into one of the above mentioned tubs (No. 2.) they put one carr of the prepared nitrous earth, that is, about four amphors; then they fill up the veffel with cold water, though fome warm it, and add a quantity of afhes, if none had been mixed up with the earth, ftirring the whole well with a wooden staff; then they fuffer

it to ftand twenty-four hours, only ftirring it by times. After this fpace they fuffer the ley to run out at the hole near the bottom, and put it into the two large cafks, (No 3.) They clear the tubs of the elixiviated earth and put in fresh, and thus the operation is continued as long as the boiling of the nitre lafts.

. In this decoction of the nitre, what they call the mother of nitre is abfolutely neceffary. This is the infpiffated lixivium remaining after the cryftallization of nitre, which cannot itfelf be made to cryftallize wherefore, this they keep from one year to the next; and for want thereof, the decoction must be continued at leaft a week before any cryftallization can be performed as it ought to be. The reafon of which feems to be, that the lixivium is not fufceptible of a degree of heat fufficient for fending off the pinguinous and alkaline parts, which neceffary denfity is given it by the mother of nitre, as it contains a copious calcarious earth diffolved in the acid of falt and nitre. When the lixivium, has acquired this pitch, the reft of the operation is eafily performed.

Of this mother of nitre they pour one or two tubs into the boiler, to which they add the new ley collect ed in the great cafks till the boiler is full; then they kindle the fire, and keep the contents boiling near twenty-four hours.

As foon as they perceive any marks of cryftallization on the furface, they remove the ley thus decocted and infpiffated into the thirty-two wooden coolers described in No. 4, and let it remain there twenty-four hours; in which VOL. VII.

time the cryftallization being completed, they drain off the mother of nitre, and return it into the boiler. The cryftals are taken out and dried, but as they never prove clean, they are again diffolved in clean water, filtered through a flannel bag, and boiled up again in a leffer boiler to a requifite thickness, and then cryftallized again, which brings them to be fit for sale. To the mother of nitre returned into the boiler, they in like manner add more fresh ley from the two great cafks, boil it twenty-four hours, and then cryftallize. In this manner is the work carried on all the fummer, and till the winter's froft puts an end to it.

One day's produce they call doba, amounting in weight to at leaft one kamien, or fourteen oko, that is, about twenty-four common pounds. About one oko, or three pounds, is loft in the purification. A fingle pound of falt-petre fetches, in time of war, upon the spot where it is made, four rubles (feventeen fhillings) but in time of peace it is much cheaper.

Now fuppofing one carr or four amphors of loose nitrous earth prepared with afhes to make four cubic feet; it follows, that from 400 cubit feet of fuch earth there may be obtained about 40 pounds of falt-petre, and that one pound of it refides in ten cubic feet of prepared earth, or in feven or eight pounds of the more compact native earth; though fuch a computation fhould not be deemed very accurate.

The earth thus cleared of its nitre is caft out of the tubs in heaps about four feet high, and fo left for the space of four years, at the end of which the maydan L

are

are brought thither, and a like quantity of nitre is got out of this earth as before. Upon a third working, after seven years more, it ftill yields fome nitre, but fcarce enough to defray the coft.

I make no doubt but this method of making falt-petre came hither from the eaft; and that it is done by a fimilar procefs in India and China. Several authors have defcribed the method of doing it in other parts of Europe. They all require earth and athes, and in fome, urine and quick lime is employed. The mixture is expofed to the air in all of them either open or under fheds. Some throw it up in heaps, others depofit it in pits; which ever way it is done it infallibly produces nitre, though in very different quantities, and that chiefly in proportion to the fatnefs of the earth.

Salt-petre is confiderably different as to its degree of purity. The natural fort of the first decoction always holds a portion of common falt. Its cryftals are not prifmatic, but cubic, and it is much of the fame goodnefs as that which has a mineral alkaline bafis, whether from common falt or otherwife; for it affumes its figure always from an alkali, not from an acid, notwithstanding Dr. Linnæus has founded good part of his fyftem of foffils on this error. If too much calcarious earth and too little afbes be combined in the decoction, the cryftals will not be fo hard, and if diffolved, may be precipitated by an alkali, which good nitre will not fubmit to. If the afhes be from hard wood, the cryftals will be firmer and larger, as are thofe of India. If the earth has any metallic intermixture, efpe

cially of iron, it will impart a tincture to the nitre. Hence the Indian falt-petre is of a reddifh hue, and the fumes of the aquafortis made from it are remarkably red in comparison of those from the Polish. This latter, mixed with English vitriol, yields a green aquafortis, which turns a precipitated folution of mercury yellow, and by cohobation, white. In a word, the chemifts give the preference to the Polish falt-petre in all operations.

Nitre may be purchased at a much eafier expence by the English, Dutch, Poles, and Ruffians, than it can be made for at home; the reafon of which is the cheapness of wood-fuel, which may be had, in a manner, for fetching. In the Pruffian dominions alone, there is perhaps more falt-petre made than in all Europe befides; and yet I do believe that scarce a thoufandth part of what was confumed in the late wars was of European produce. Earths rich in volatile falt and nitrous particles turn to far better account in manuring land and feeding the inhabitants, than in furnishing deftructive falt-petre, which ought rather to be fought after in barren defarts.

TH

HIS bridge is called by the natives Point y ddy prydd. It lies on the river Taaf, at Lantriffant, near Llandaff, about ten miles above Cardiff, in Glamorganfhire. This bridge is no more than 8 feet broad, but it confifts of a fingle arch no less than 140 feet wide, part of a circle of 175 feet diameter, fo as to make the altitude 35 feet. It is therefore 4 feet wider than the celebrated Rialto of Venice, and probably the wideft arch in Europe, if not in the world at least I never read of any thing equal to it, that can be relied upon as matter of fact. The accounts given by fome of the Popish nilionaries of fome

bridges in China look more like fables than realities.

The building of this bridge is well worth recording. About 12 or 14 years ago William Edward, a country mason, a native of the parish of Eglwyfilan in that county, agreed with the hundreds of Mifkin and Singhenith to build a bridge over the river Taaf in four arches for 5001. and to give fecurities to infure it for feven years. This bridge was finifhed, but a great flood in this rapid river entirely carried it away in lefs than two years time. He was then obliged to begin again. But he thought with himself that if he could build a bridge in one arch, it would be out of the power of the flood to hurt him a fecond time; and he was pofitive in his own mind that it was practicable. When he made this propofal to his fecurities they looked upon it as a very whimsical scheme; however at laft they confented, and he fet about it with all the eagernefs of a projector. But when he had almoft finished the arch, the center timber work gave way, and all fell to the bottom.

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He now began again, erected ftronger timber work, fairly completed the arch, the center was knocked off, and it stood, the wonder and amazement of all beholders; and perfons of curiofity came to fee it from feveral diftant

parts of the kingdom. This was in the year 1755, when a copperplate plan, and profpect of this furprifing arch were published, dedicated to Lord Windfor, the lord of these manors. But the misfortunes of the poor mafon were not yet over. He was no mafter of the rules of architec

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ture,