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Thus nitre by diftillation may be almoft wholly reduced to an acid fpirit ; but if it be burnt with tartar, or charcoal duft, it becomes an alkali fait, called fixed nitre : this, if fuffered to run perdeliquiurn, and afterwards filtred thro' cap paper, will leave a large quantity of earth behind ; and if the Came liquor "be diftilled°to drynefs, an infipid water will come over, and the fait remaining at the bottom of the retort, will be found to have loft a great part of its quantity ; and if the operation be often repeated, nothing will at length remain but earth. Again, the vitrification of alkaline falts feems to be nothing but the convcrfion of them into earth ; for glafs has no qua- lities different from thofe of earth.
"What we have proved by experiments, in refolving bodies, may be farther confirmed by others relating to the formation and corrtpofition of them ; and particularly by Van Helmont's famous experiment of the willow. He took about two hun- dred pounds of earth dried in an oven, and put it into a vef- fel covered with an iron-lid full of holes: in this earth he fet a branch of willow, weighing about five pounds; which foon took root, and grew fo much, that in eight years time it weigh- ed one hundred and fixty pounds ; the earth it ftood in having, during al! this time, loft only a few ounces ; fo that the whole jncreafe of the tree muft have been owing to rain water, with a very final] proportion of earth ; and the falts and fulphurs therein muft have been compofed of two elements alone The experiments of this kind, made by the illuftrious Mr. Boyle on fmall fprigs of mint, marjoram, balm, pennyroyal, tsY. fet in fmall vials filled only with pure water, are yet more to be depended on. Thefe increafe in a fhort time to double their firft weight j and being aferwards diftilled, they yielded the very fame principles they would have done, had they grown in the moft proper foil. From all this it cannot but be allowed, that fait and oil owe their original to water and earth. Water and earth do indeed, in the flricteft fenfe, deferve the name of principles; but in the formation of mixed bodies a third principle muft necefTarily concur with them ; for as they are of themfelves wholly unactive, foraething muft be fup- pofed to give them their motion and a&ivity : without this, water would immediately turn to ice; and as there are few bodies out of which fire may not be drawn, it is evdient that there muft be fome active, moveable principle in them all, to which the motion of the other parts is owing. There- fore, tho' this principle mould not fall under our fenfes in the fame manner as the others do, that can be no reafon for doubting its exiftence, fince it muft concur in the compofi- tion of all bodies ; which, if they were made of water and earth alone, would remain for ever without any virtue or ener- gy. This they muft receive from another principle ; and ac- cording to the different combinations of all the three, bodies are formed with different properties and powers. We ac- knowledge, therefore, three fimple fubftances in bodies, which are properly elements or principles j one active, which may be termed fire; and two paffive, water and earth. From the moft fimple union, or connection of thefe three, fait arifes; which confequently is to be looked upon as the moft fimple of all mixed bodies. The next to that in fimplicity is ful- phur or oil, made by an union of thefe three principles, and of fait. Geoffroy, Tract, p. 5.
Elementary earth is the fame with the terra damnata, or ca- put mortuum of the chemifts ; being a fimple, friable, porous fub (lance, without fmell or tafte, confifting of particles of no regular figure, and altogether unfit for motion. The poro- fity of earth feems to arife from the irregular figure of its par- ticles ; and as thefe particles oftentimes touch one another on- ly by their angles, the whole mafs muft necefTarily be friable, and the want of tafte and fmell may be owing to the inap titudeof the particles of earth to motion. Jn any analyfis of bodies, the laft thing is always this princi fie earth ; and in their compofition it feems to fervc as a ba fis or foundation to the other parts of the mixture, and to it the drynefs, folidity, and hardnefs of bodies is in a great mea fure to be afcribed. Geoffrey, Tract, p. r r. Elementary water is a fimple liquid, infipid, inodorous, pellu- cid fuhftance: its fluidity is owing entirely to the action of fire, and. when that action is very great, its parts are actually divided, and the whole turned to vapours ; but when it is very fmall, they cohere ftrongly, and turn to ice. This element fome chemifts call phlegm, and it may be conceived to confift of fmall fmooth particles, of an oblong or oval figure, and perfectly rigid and inflexible. From the minutenefs of its particles it eafily penetrates the pores of almoft all bodies. An oval figure feems more agreeable to the fluidity of waters, as alfo to its motion, than a fperical one ; and likewife to the folidity we ohferve in ice, the points of contact in fpherical bodies being too few to form fo ftrong a cohefion. Were its particles angular and flexible, they would be too weak to pe- netrate and dlfiblve falts, and would likewife he too much re- fitted ; but as their furface is fmooth, they can eafily enter the fubftance of falts, and afterwards as eafily feparate their parts, that is, diflblve them by their rigidity and oval figure. f he want of tafte and fmell in water feems to be owing to the fmoothnefs, obtufenefs, and fmailnefs of its particles, which cannct vellicate the nerves of the tongue and noftrils. 1 he fluidity of the water arifes from the fmailnefs, fmooth- Svpp. Vol. 11.
riefs and figure of its particles, and from their eafy motion! by the fire contained in their interftices. Without the action of fire feparating thefe particles, and keeping them in continual motion, their fluidity would prefently fee loft, how much foever their natural figure may difpoie them to it, and they would become one folic! mafs. On the other hand, if the action of fire upon them be very great^ they are farther feparated from one another, and fly off in vapour and fmoke. In fine, water is tranfparcnt, becaufe its pores are fo difpofedj as readily to tranfmit the rays of light. Ge-ff. Tract, p. 10. We reckon elementary fire the firft principle of bodies, as be- ing that from whence all the reft receive their activity: it is a fimple and moft fub tie bodv, in a continual fwift motion, filling and eafily penetrating the pores of all other bodies. Its immenfe fubtlety is evident from this, that it pervades all bodies whatsoever, and its fwift motion from that rapidity which it is capable of communicating to them- Its force is in proportion to the quantity of it any where collected. In the fun, which may be looked upon as a vaft congeries of this fubftance, its motion is moft violent. In culinary fires, the quantity and motion of it are not fo great, but ftill greater than in fpirituous and volatile liquors, where it is h'ard'y to be perceived, except when they are fet on fife. Not only all motion, but alfo heat is owing to fire^ which as it exifts in bodies, is nothing elfe but the exceffive motion of their parts. It is too fubtle and active ever to be collected pure in chem- cal analyfes ; wherever it is found it is always unit d with water and earth in faitr. and fulphurs ; and is f ;inetimes con- centred in bodies in (o great quantitie:--, as confidently to in- creafe their weight; as is evident in calcined antimony, in which there is in the operation an addition made of almoft a fifth part. Geoffroy, Tract, p. 9.
What the chemifts call oil or fulphur, is not a fimple fub- ftance, but a body compounded of earth, fire, water, and fait; but as it is ufually feparated entire in chemical analyfes, it has been ufually efteemed a chemical principle or element of bodies ; and is, indeed, tho' a real compound, yet not without confiderable difficulty to be reduced to its principles. It may be defined to be a fluid, vifcid, inflammable, transparent body, without tafte or fmell, (tho' by mixing it differently with falts thefe different qualities are produced) compounded of fire, water, earth, and fait ; and it may be conceived to confift of many flakes, or floccuii, each of which is again made up cf very fmall flexible filaments, formed of the four principles before mentioned, by fermentations, as well in the bowels of the earth, as in the bodies of vegetables and ani- mals; thus an aromatic plant grov/mg in water wdlj hv dif- tillation, yield an oil, which could never h:ive been obtained from the water in which it ftood ; and all oils may by art be refolved into water, earth, and fait : from thefe filaments va- rioufly concreted arife the flakes already mentioned, which are of different thickneffes; and in the pores thereof is lodged the element of fire, which alfo runs in little ftreams thro* their interftices. On thefe depend the fpecific levity, in- flammability, and fluidity of oil ; but as notwithftanding the inteftine motion caufed by the element of fire, the floccuii ftill adhere, in fome meafure, together; this fluid muft ne- cefTarily be more vifcid than any other.
From what has been faid concerning the nature of alkaline falts, and the figure and ftructure of the oily floccuii, it is eafy to conceive why all alkalies diffolve fulphurs ; for fince the alkaline particles are fpherical and pricklv, they cannot enter the interftices of thefe floccuii, without carrying aWay fome of them from the reft, and thus by degrees thoroughly dillblving them. But the denfe, rigid, and pointed molecule: of acids being laid into thefe interftices, increafe the denfity, and ftrengthen the texture of the floccuii ; and from the di- verfity of thefe and of the acid fpicula mixed with them, arife the different kinds of fulphurs.
Sulphurs formed in the earth, of fire,- acid fait, watery and a very fine earth, are termed fimple bitumens, and thefe bi- tumens difiblved in a large quantity of water, form the mineral oils or petrolea ; hut if they are mixed with earth and fait, the common folid bitumens are produced, differing from one an- other in degrees of purity, according to the quantity and grofs- nefs of the earth, or different degrees of mixture. Thus fof- file or pit-coal, jet, amber, and the common bitumens, and bi- tuminofe earths arepioduced. If there be but a fmall quantity of earth and much acid fait, the common mineral fulphur or biimftoneis formed : if the mineral original bitumen is joined to a fufible earth, capable of vitrification, it communicates to it a metallic form, that is the found, brightnefs, foftnefs, ductility, malleability, and all the other fenfible qualities of metals.
This origin of mineral bitumens may be confirmed by many experiments. If a mixture of equal parts of oil of vitriol, and oil of turpentine, be digefted together for a confiderable time in a very gentle heat, and afterwards diftilled in a retort, there will come over firft a yellowith liquor refembling pe- troleum both in fmell and confiftence; and what remains in the retort is at firft a foft bitumen, and afterwards turns into a hard black mafs, eafily inflammable, and fmelling in the burning exactly like foffile. coal. But if the diftillation be continued, a white acid liquor will next be obtained, which -> Bb by
