NIT

NIT

( *56 )

The fecond repolitory of native nitre is vege-table foil. It is aflerted by fome chemills,efpecially tliofe who maintain that nitre is aprodu£t of vegetation, that all foils contain nitrein proportion to their fertility : this however isby no means the cafe: Mr. Beaume lixiviatedcarefully 36 fpecimens of fertile foil, and didnot obtain a particle of nitre from any one ofthem. k There is no country in Europe the foilof which is fo rich in this fait as Spain . It isaflerted by Bowles that nearly a third of theuncultivated lands in the Eaftem and Southernprovinces of this kingdom afford it in abundanceunder the following Ample management. Theland is ploughed twice or thrice during thewinter and fpring, to the depth of three or fourinches; it lies fallow the whole fummer, andabout the middle of the autumn the foil havingbeen thus expofed to the full a£tion of the air,is carted off and lixiviated : the liquor is thenboiled down in the ufual manner, and affordsby cooling a quantity of nitre mixed with from20 to 40 per cent, of common fait.

A conflderable part of the foil in LowerHungary is richly impregnated with nitre, andfeveral of the wells and fprings are incapable ofbeing ufed as drink on account of their contain-ing from f to 4 per cent, of this fait. 1

Many of the lands in India , efpecially in thevallies of the great rivers, are exceedingly abun-dant in nitre. In the prefldency of Calcutta alonebetween 7 and 8000 tons are annually manu-factured. Sometimes it covers the furface ofthe foil with a faline efflorefcence, which beingfwept off is renewed every other day at parti-cu' .r feafons of the year. The foil of thofelands in which it is lefs abundant is raked upinto fmall heaps, and mixed with the ferapingsof roads and cattle-flails, and after being expofedfor a certain time to the aCtion of the air is lixi-viated: the earthy refldue is mixed with frefhearth, and after two years affords as large aproduce of nitre as at flrft.

In many nitrous foils the acid which theycontain is combined for the molt part with limeinftead of potafh, fo that the produce of realnitre which they afford by the ufual mode oftreatment is very fmall: long experience how-ever has taught the nitre - makers in everycountry where thefe foils occur, to remedy thisdefeCt by the addition of wood-afhes. Therationale of this, though wholly unknown tothe greater number of thofe who praCtife it, isfufliciently obvious to the chemift; the carbo-nated alkali of the afhes and the calcareousk Mem. dc Scavans Etrang. XI. p.38*.

nitrat of the foil mutually decompofe eachother, and carbonated lime and nitrated potafhis the refult. Many of the nitrous foils in India require this alkaline addition, as well as thofeof China and other parts of Afla. Much of thenitrous foil in the Crimea and Ukraine alfo isof this defeription: in appearance it refemblescommon black vegetable mould, except that itis more unCtuous to the touch, and is fo lightand of fuch little coherence as to be converted toa loofe duft by a few days of dry weather. Thofeparts of the Crimea that have been long uncul-tivated, and efpecially the artificial mounds thathave ferved for burial places and the fites oftowns, are feleCted by the nitre-makers. Thefoil being dug up is mixed with about -j- bymeafure of wood-afhes, and lixiviated in perfo-rated calks in the ufual way: the liquor thusproduced, when concentrated by repeated lixivi—ations, is mixed with the mother water of apreceding cryftallization, and boiled down for24 hours, removing from time to time the com-mon fait and muriated potafh that feparatesduring the procefs; it is now transferred whilehot into fhallow coolers, in order to cryftallize,which it does in 24 hours more. The roughcryftals being drained are again diflolved inwater, and the product of the fecond cryftalli-zation is a nitre fomewhat impure but yet in afit ftate for the market. Four hundred cubicfeet of the mixture of earth and wood-afhesafford 42 lbs of nitre of the firft cryftallization,which by the fubfequent refining is reduced to39 Ibs -

Before the general ufe of gunpowder in war,the produce of native nitre was abundantly fuffi-cient to fupply the European demand for thisarticle; but when in confequence of the uni-verfal adoption of fire-arms the confumption ofthis fait was prodigioufly increafed, it becamean important objeft for every nation, and efpe-cially thofe that were the lead commercial, toencourage by every method the domeltic manu-facture of nitre. Every kind of foil that hadthe lead refemblance to the nitre foils of Spain and India , was examined by lixiviation, and bydegrees it was afeertained that the furface foilof farm-yards, of cattle-dalls, of cellars, ofprivies, and other places long expofed to thevapours of putrefying animal matter, afforded,when mixed with wood-afhes and lixiviated, aconfiderable quantity of nitre. It was alfodifeovered that the plaider, mortar, and whatis included under the general term brick-rub..Lifh of old houfes, was capable of yielding thi*1 Ruckert, Journ. des Mines, No. 3, p. 13.