Page images
PDF
EPUB

Homberg is the pure falt, falt the principle, in it felf fimilar and uniform, but never found alone, And although this principle be called the falt of the earth, yet it fhould feem it may more properly be called the falt of the air, fince earth turned up and lying fallow receives it from the air. And it fhould feem that this is the great principle of vegetation, derived into the earth from all forts of manures, as well as from the air. The acid is allowed to be the caufe of fermentation in all fermented liquors. Why therefore, may it not be fuppofed to ferment the earth, and to conftitute that fine penetrating principle, which introduces and affimilates the food of plants, and is fo fugitive as to escape all the filtrations and perquifitions of the moft nice obfervers?

127. It is the doctrine of Sir Ifaac Newton and Monfieur Homberg, that, as the watry acid is that which renders falt foluble in water, so it is that fame which joined to the earthy part makes it a falt. Let it therefore be confidered, that the organs (d) of plants are tubes, the filling, unfolding, and diftending whereof by liquors, doth constitute what is called the vegetation or growth of the plant. But earth it felt is not soluble in water, fo as to form one vegetable fluid therewith. Therefore the particles of earth must be joined with a watry acid, that is, they must become falts in order to diffolve in water; that fo, in the form of a vegetable juice, they may pafs through the trainers and tubes of the root into the body of the plant, fwelling and diftending it's parts and organs, that is, increafing it's bulk. Therefore the vegetable matter of the earth is in effect earth changed into falt. And to render earth ·

[ocr errors]
[blocks in formation]
[ocr errors]

fertile, is to cause many of it's particles to affume a faline form.

128. Hence it is obferved, there are more falts in the root than in the bark, more falts in vegetables during the fpring, than in the autumn or winter, the crude faline juices being in the fummer months partly evaporated, and partly ripened by the action and mixture of light. Hence alfo it appears, why the dividing of earth, fo as to enlarge it's furface, whereby it may admit more acid from the air, is of fuch ufe in promoting vegetation. And why afhes, lime, and burnt clay are found fo profitable manures, fire being in reality the acid, as is proved in the fe quel (a). Marls alfo and fhells are ufeful, forafmuch as thofe alcaline bodies attract the acid, and raise an effervescence with it, thereby promoting a fermentation in the glebe. The excrements of animals and putrid vegetables do in like manner contribute to vegetation, by increasing the falts of the earth. And where fallows are well broken, and lye long to receive the acid of the air into all their parts; this alone will be fufficient to change many terrene particles into falts, and confequently render them foluble in water, and therefore fit ali ment for vegetables.

129. The acid, faith Homberg, is always join ed to fome fulphur, which determines it to this or that fpecies, producing different falts, as it is the vegetable, bituminous, or metallique fulphur. Even the alcaline, whether volatile or lixivial falts, are fuppofed to be nothing but this fame acid ftrictly detained by oil and earth, in fpight of the extreme force of fire, which lodgeth in them, without being able to diflodge fome remains of the acid.

(a) 202.

130. Salts,

130. Salts, according to fir Ifaac Newton, are dry earth and watery acid united by attraction, the acid rendering them foluble in water (f). He fuppofeth the watry acid to flow round the terreftrial part, as the ocean doth round the earth, being attracted thereby, and compares each par ticle of falt, to a chaos whereof the innermost part is hard and earthy, but the surface soft and watery. Whatever attracts and is attracted most frongly is an acid in his fenfe.

131. It seems impoffible to determine the figures of particular falts. All acid folvents together with the diffolved bodies are apt to fhoot into certain figures. And the figures, in which the foffil falts cryftallize, have been fuppofed the proper natural fhapes of them and their acids. But Homberg: hath clearly fhewed the contrary: forafmuch as the fame acid diffolving different bodies, affumes dif-. ferent fhapes. Spirit of nitre, for inftance, hav-. ing diffolved copper, fhoots into hexagonal cryftals; the fame having diffolved iron, fhoots into irregu-: lar fquares; and again, having diffolved filver, forms thin cryftals of a triangular figure.

132. Homberg nevertheless holds in general, that acids are fhaped like daggers, and alcalies like: fheaths and that moving in the fame liquor, the daggers run into the fheaths fitted to receive them, with fuch violence as to raife that effervefcence obferved in the mixture of acids and alcalies. But it feems very difficult to conceive, how, or why the mere configuration of daggers and sheaths, floating in the fame liquor, fhould caufe the former to rush with fuch vehemence, and direct their points fo aptly into the latter, any more than a parcel of fpigots and foffets floating together in the fame water, hould rush one into the other.

[merged small][ocr errors][ocr errors][merged small]

133. It fhould feem rather, that the vehement attraction which Sir Ifaac Newton attributes to all acids, whereby he fuppofeth them to rush towards, penetrate, shake, and divide the most folid bodies, and to ferment the liquid of vegetables, could better account for this phænomenon. It is in this attraction, that fir Ifaac placeth all their activity, and indeed it should feem, the figures of falts were not of fuch efficacy in producing their effects, as the ftrong attractive powers. whereby they are agitated and do agitate other bodies. Efpecially if it be true (what was before remarked) that lixivious falts are alike purgative, whatever may be the fhape of their angles, whether more or lefs acute or obtufe.

134. Sir Ifaac Newton accounts for the watery acids making earthy corpufcles foluble in water, by fuppofing the acid to be a mean between earth and water, its particles greater than thofe of water, and less than those of earth, and strongly to attract both. But perhaps there is no neceffary reafon for fuppofing the parts of the acid groffer than the parts of water, in order to produce this effect; may not this as well be accounted for, by giving them only a ftrong attraction or cohefion with the bodies to which they are joined ?

135. The acid fpirit or falt, that mighty inftru-. ment in the hand of nature, refiding in the air, and diffused throughout that whole element, is difcernible alfo in many parts of the earth, particularly in foffils, fuch as fulphur, vitriol, and alum; it was already obferved from Homberg, that this acid is never found pure, but hath always fulphur joined with it, and is claffed by the difference of its fulphurs, whether mineral, vegetable, or animal.

136. Salts are vulgarly reckoned the moft active of chemical principles. But Homberg derives all'

according to the refiding in the oil, This is otherwife

their activity from the fulphurs joined with them. From which alfo, as hath been faid, he derives all their kinds and differences (g). Salt, water, oil, and earth feem to be originally the fame in all ve getables. All the difference, chemifts, arifeth from a fpirit called the Rector or Archæus. called by chemists, ens primum, or the native fpirit, whereon depend, and wherein are contained, the peculiar flavour and odour, the specific qualities and virtues of the plant.

137. Thefe native fpirits or vegetable fouls are all breathed or exhaled into the air, which feems the receptacle as well as fource of all fublunary forms, the great mafs or chaos which imparts and receives them. The air, or atmosphere, that furrounds our earth, contains a mixture of all the active volatile parts of the whole habitable world, that is, of all vegetables, minerals, and animals. Whatever perfpires, corrupts, or exhales, impregnates the air; which, being acted upon by the folar fire, produceth within itself all forts of chemical operations, difpenfing again thofe falts and fpirits in new generations, which it had received from putrefacti

ons.

138. The perpetual ofcillations of this elastic and reftlefs element operate without ceafing, on all things that have life, whether animal or vegetable, keeping their fibres, veffels, and fluids in a motion always changing; as heat, cold, moisture, dryness, and other caufes alter the elafticity of the air. Which accounts, it must be owned, for many effects. But there are many more which must be derived from other principles or qualities in the air. Thus iron and copper are corroded and gather ruft in the air, and bodies of all forts are diffolved or corrupted,

(g) 129,

« EelmineJätka »