Mr. Jeremiah Brown's method of on the straw in the bottom of your

making falt petre ; published in lye veffel, which would retain the

Virginia by order of the truftees water to be poured on it too long, for the improvement of arts and and overcharge it with faline parmanufactures, and in England ticles, to the great interruption of by order of the society for the the process : place the earth holencouragement af arts, manufac- low in the veffel, for the reception tures, and commerce.

of the water; the first put to it must

be warmer than new milk from the SALTPETRE is to be found in cow; afterwards add cold water :


fix a vesiel to receive the lye as soon houses, hen and pigeon-houses, you begin to put the water in, as it and in any covered place where will not remain long upon the the influence of the sun seldom earth, but in a few minutes begin reaches. A fixty-feet tobacco- to drop into the receiver : if it house will yield upwards of 16 c. runs foul, it must be returned: weight a year, and so in propor- upon the earth: as soon as it tion for larger or smaller houses. has dropped a gallon, you may

In order to prepare the floors for begin to boil it in a cast-iron pot. attracting nitre, all dung and other Every bushel of earth will require trath must be removed ; and if near eight gallons of water. Conthe floors are not level, they must tinue to boil it gently until you be made so by laying on marle, or have fully charged your pot with any fail not too ftiff, which must be the lye, and you will find the watry lightly trod down with the feet.

particles evaporate until it is reThe floor being thus prepared, duced to a thick oily confiftence, sprinkle strong ambeer over it, shooting into small icy crystals, made from tobacco-trash, and co which you will easily perceive by ver it with wet ground leaves, or exposing the suds, in a spoon, to other tobacco-trarh, for a fort a cold place : then put the liquor night; then clean out the trash, and out of the pot into wetted wooden in any cool dry morning that suc- trays, and set it by in a cool place ceeds, you will find on the floor for the first growth: if you acci. the nitre attracted and condensed dentally boil it too thick, add a like hoar-frast; sweep this off light- little cold water : when your trays ly, and put it by in fome hogf- have stood with the suds a few heads, or safe place in your houfc, hours, you must raise one end to till you have leisure to go through let the lye drain off from the faltthe following process. This work petre, which is the first growth, you must carefully repeat as often and which, by boiling a second as you observe the abovementioned time, will yield you a fresh quanappearance of nitre on your foors; tity. by which means you will be fur After it is thus drained and benihed with a competent quantity come dry, you may put it into to employ a leisure day,

casss or tubs, until you

have The process. : Make a lye from leifure, without prejudice to your this earth in the fame manner as is crops, to refine. usually done for soap, noting that To refine salt-petre. Put into the earth is not to be hard packed your pat about a third of the


quantity it will hold of this first shoot into cryftals; then pour it growth, and set it over the fire: you into your tray, with dry sticks are to be provided with an iron rod, fixed across, so as to be a little beor poker, to ftit it: as soon as it low the surface of the liquor; fet begins to melt, you will see it be- this by in a cool place, where it gin to boil furioufly: keep it well may stand until it shoots into clear ftirred down, as at this time it is transparent crystals ; then pour very apt to take fire, which will off the liquor, and set the tray to destroy the whole : when you ob- as to drain it off perfectly dry. serve it in the boiling to look of a Thus your falopetre is comdirty white, flacken your fire, and pletely made, and in a few days ftir it brisky for a quarter of an will be dry enough to remove out hour; then increafe your fire, and of your trays into calks or vessels continue the ftirring, though the proportioned to the quantities, danger of burning it is now over : The liquor you last poured on the pot, before it is fafficiently must be again evaporated over the melted, will be, at the bottom, of fire, for it will yield faltpetre a faming red, and the matter will equally good as the former ; and appear like boiled cream ; and thus continue the operation, until when it becomes whitish and li- all the watry particles are totally quid, pour it upon a ftone, or evaporated. fome earthen vessel, or a hard well. N. B. The earth, from which rammed earthen floor, clean swept. you have extracted the saltpeure, As soon as it is cold, it will be- and all the washings of your velcome hard, and if you throw it fels, if you lay it by thinly spread, upon a stone, will ring like broken in your house, will turn to profit

, china.

as it continues to be peculiarly If you have not leisure imme-' proper to attract and absorb the diately to clarify it, put it into a nitre floating in the air ; add also tub in a dry place until some con the earthy matter which settles in venient opportunity.

the refining: and should you be in To clarify coagulated cream of want of house-room, you may nitre. To every pound of this spread it upon the earth, covered matter put six pounds of water, in the manner that fodder facks after you

have broke it into small are: it will produce falopetre fall pieces : put your pot upon the fire, as well as a tobacco-houfe, taking and stir it until it is well dissolved; care that the north-end be always then make the fire all round the open, and that it be defended as pot, which will cause it to boil in much as poslible from rain. the middle, and prevent any waste by its drying and sticking on the fides of the pot; and as soon as the A new process for obtaining Nitre. earthy matter begins to settle in the poi, pour the liquid into a


Have lately seen in the public tray, or other open veifel, that its papers mention of a design to sediment may fertle: pour off the establish in this kingdom the maclear liquor, and evaporate it with nufacture of nitre; and being de gentle fire, until in a spoon it will sirous to contribute all that lies in

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my power to so useful an under- further observes, that the substances taking, I fall with your concure which fupply nitre in greatest rence submit to the public, a de plenty are the rubbish of demotail of some proceedings I made lished houses, all kinds of earth, , fome years ago for procuring that clay, and loam, lime, afhes, and necessary article; in which I not soap-boilers dregs; and that these only mean to point out what the always produce most nitre, in pro-, constituent parts of nitre are, and portion as they are combined with deliver a method of making it here, , the excrements and urine of anibut, by the recital of various expe- . mals, and with corrupted vegew: riments ineffectually made on the tables. All these materials I foon materials best recommended for the furnished myself with, and for purpose, prevent any further ex- greater certainty procured fome of pectations from those substances; them from different places; but: and hope, for the future, to secure after frequent trials by drenching every person from falling a prey to and boiling them in water, could the insinuations of impoftors and not procure any thing at all like ignorant pretenders to the art, as nitre from them. I then provided hath already been too often expe a great number of flat glazed rienced. Having perused what Hoff earthen pans, and in these exposed man, Stahll, Boerhaave, and others, the fame substances for several have delivered on the formation of months in a dry state to the air, nitre ; and being furnished with an but found myself equally disapaccount of the nitre works near pointed. I likewise placed in the Paris, and with the method of fame situation a quantity of the making this falt at Calcutta, I en- vegetable alcaline falt, called pearl tered upon the subject with as. alh, some of it alone, and some much asliduity and attention, as a mixed with the forementioned man can apply to one he is either earthy substances; but to no better pleased with, or interested in. The purpose; for which I am induced writers above mentioned differ fo to believe, notwithftanding the aulittle in their accounts of the con- thority of Hoffman, and the opiftitution of nitre, and the mate- nion of many concerning the refipials which supply it, that I shall, dence of the nitrous acid in the air, for brevity fake, confine myself to that it is not to be found therein; what is delivered by Hoffman; and this I am the better authorised who is, indeed, more particular to deliver, as I never could proand extenfive on the subject than cure, after proper trials, any verany of the rest. He says, in the tiges of nitre from hail, snow, first place, that nitre has two prin- rain-water, or dew. These expeciples or elements ; one the uni- riments terminating wholly fruitversal primogenial simple acid, less, I determined to go back to which inhabits the air quod ventre the place where once intended to Swo portat, the other an alcaline set off from; if the accounts I had fulphureous fat earth ; and that this met with in authors had not fatlalt is a matrix which by attracting tered me with hopes of a more to itself, and imbibing the former speedy mode of acquisition. The from the air, constitutes nitre. He decomposition of nitre was now un

dertaken ;

dertaken; it was well known that bifh of old houses in France affords every kind of falt consists only of nitre, while from rubbish in Engtwo materials, an acid, and an al- land, where no wood ashes are cali; but the decomposition was used, nothing like nitre can be obperformed to come at the propor- tained. The nature of the alcali tions of those materials, and more of nitre thus determined, there reespecially that the nature of the al- mained nothing more than to find cali, in the conftitution of nitre,, the residence of the nitrous acid; might be precisely known. Two and having failed of it both in methods were made use of for this earthy subitances, and in the air, purpose, the distillation of nitre in I resolved to search for it in water. a retort to procure its acid apart All waters that are averse to a fofrom it's alcali

, and the deflagra- lution of soap, and commonly calltion or calcination of nitre in a cru ed hard, are known to be impregcible, to procure its alcali separate nated with a mineral acid, and that from its acid. The procesies for however bright and transparent these purposes are so well known such waters appear, they always that there is no occafion to describe contain as much earthy or metalthem; I shall only take notice here line matter of some kind or other, that the alcali procured from cal- as the fort and quantity of acid they cined nitre was found in all re are poffeffed of is capable of disfpects, and in every mode of trial, solving; it was, likewise known, fimilar to that which every kind of that by adding the vegetable alcali vegetable burnt to ashes affords. to any such water, the combination

That this alcali being added to the of its acid and mineral would be acid obtained by the distillation be- destroyed, and a new substance or fore mentioned, recomposed a pure falt be composed by the vegetable and perfect nitre, and that nitre alcali taking the place of the miequally pure was obtained by fa- neral ; but these kind of waters turating the same acid with the had not been so fully and artfully common vegetable alcaline falt, examined as to be sufficiently known called pearl aih. From this account and properly distinguished; they it will appear that nothing more is had pafled promiscuously by the wanting to the formation of nitre, character of vitriolic waters. In than a suitable combination of a order to satisfy myself more partivegetable alcaline falt with the ni- cularly concerning their qualities

, trous acid; and that all that Hoff. I procured spring-water from vaman and others have said of the use rious places in and about London, of alcaline and fulphureous earths, and among them met with several, excrements, and putrefied veget. which by adding a solution of pearl ables, has served to mislead those ash in common water, had their who have attempted the manufac- mineral matter precipitated, and ture in England; neither of those afforded a pure nitre. It may not fubftances can poffibly produce be amiss here to explain the nature nitre, if no vegetable alcali has of precipitation. The tenure that been mixed with them ; and it is every kind of dissolved matter has moft probably owing to the use of in a folvent, is held only by a dewood ashes in mortar that the ruba gree of affection, if it may be fo


called, between the two parties, like small beer, then set it by, and and is always found to give way to fjon after it is grown cold it will fuperior influence, viz. to a greater shoot into crystals. The system affinity between one of the parties, of crystallization is, That water and some substance added, than can only diffolve, and keep fu. does fubfift between the parties firit fpended in it, a certain fixed quananited; this is the caule of every tity of every kind of salt; but tha kind of chemical precipitation. quantity soluble in warm water Gold diffolved in aqua regia is pre- greatly exceeds that in cold; fa cipitated by aditing copper to the that when any water, fully charged solution ;

the copper in the same with salt by the affiftance of heat, manner gives way to iron, and iron is reduced to a state of cold equal to an earth or vegetable alcali. In to air, so much of the salt as owed the same manner, and by the fame its Colution to the imposed heat of law, all waters that are impregnate the lixivium, will shoot into cry ed either with the marine, the vi- ftals, but no more ; and thus by triolic, or the nitrous acid, and succeslive evaporations of a lixia which have their acid faturated or vium, all its fait may be separated neutralised by any kind of mineral from it. . The speediest way of they have met with in their passage knowing if the lixivium, or springor residence under ground, will be water which has been faturated obliged to part with that mineral with pearl-afh, will afford nitre, by adding to them any kind of ve is this: As soon as the lixivium is getable alcali ; and this by the reduced by boiling to a brown cogreater affinity there is between lour, dip into it a piece of whitish their acid and a vegetable alcali, brown paper, and having made it than between their acid and any thoroughly dry, apply it to the kind of earth or metal whatever. flame of a candle, where, if instead

of being set on flame, it only takes The method of making Nitre. fire, and runs on in circular bright

sparks, until all the paper is conTo any quantity of fpring-water fumed, it is certain it will afford which contains the nitrous acid, perfect nitre. It is very obvious, put some solution of pearl-ath in after all, that nitre cannot be made common water; this immediately to advantage in this way in, or near will make the spring-water turbid; London; the evaporation of fo add gradually more of the solution large a portion of water, which the of pearl-ath, as long as any clou- lixivium must neceffarily fuffer to diness is made in the water, but bring it to a state of crystalliza, no longer : the saturation of the tion, will be too expensive in the nitrous acid with the folution of article of fuel ; yet there are means pearl-afh fhould be nicely adjusted. of leffening this expence, and putSuffer the liquor to stand undi- ting all the proceedings into fucha fturbed till all the cloudiness is way as may make it be found a fallen to the bottom; when this is profitable undertaking; but the done, decant the clear liquor from display of this and other circumits sediment, and boil it until it is stances 'necessary for carrying on reduced to a brown colour, not una fuch a work, must be referred, for


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