Page:Cyclopaedia, Chambers - Volume 1.djvu/110

 ALK

C*3)

which by length of time, or fome other Caufe, are become

flony, or even earthy ; as the folTil Unicorn's Horn, C?c.

Laftly, almoft all Stone Marine Plants, as Coral &c.

After all, the Alkaline Property does not appear to be na- tive, but rather producible by Art. — This Opinion feems to have been firft flatted by Helmont : before him, it was the flanding Opinion, that Fix'd Alkalies pre-ex'ifted in mix'd Bodies ; and were only feparated or extricated from the Parts of the Compound. Helmont advanced, that they did not thus pre-exift in their alkaline Form, but were Pro- duflions of the Fire, by whofe violenr Aflion, part of the Salt which in the Concrete is all volatile, lays hold of fome part of the Sulphur of the fame Body ; and both melting together, are fixed into an Alkaly : which Fixation he ex- emplifies, by what happens when Salt-petre and Arfenick, tho both volatile, being expofed to the Fire, are flux'd by the Operation thereof, and made to fix each other.

Some late Chymifts, and particularly M. Geoffrey, carry the Point fomething further, and affert, that all Alkaly Salts whatever, both Fix'd and Volatile, are wholly the Ef- fea of Fire ; in that before any Aflion of the Fire, they did not pre-exift in the Mixt wherein they afterwards ap- pear'd. See Fire.

Notwithflanding all the feeming Oppofition and Hoftility between Acids and Alkalies, they may be converted into one another ; at leaft, Acids are convertible into Alkalies ■ as is Ihewn at large by M. Geoffrey in a Difcourfe exprefs, in the Mem. de I' Acad. An. 1717, where the Nature and Origin of Alkalies is excellently explain'd.

Alkaly Salts, according to this Author, are only Acids concentrated in little Molecules of Earth, and united with certain Particles of Oil, by means of Fire.

When an Add, which we conceive in the general as a final!, folid, pointed Spiculum, happens to be abfotb'd or concentrated in a proper Portion of Earth ; the whole be- comes denominated a Saline, Compound, Neutral, or Inter- mediate Salt 3 by reafon the Acid, thus inclofed in a Sheath, cannot excite the fame Savour as when difengag'd there- from ; and yet excites a faline Tafte : and for this reafon is compound, S3c.

Now, Fire is the only Agent capable of difengaging the Acid, from the Earth it is thus invefted withal. Upon this, the Acid being lighter than the Earth, rifes, and evaporates ; leaving the Earth at the bottom of the Veffel ; which for this Reafon is called Fix'd, in contradiftindlion to the Acid, which is Volatile. This Earth, thus bereav'd of its Acid, is Jeft with its Pores open and empty, which before were fiU'd ; and withal, in iiiftaining the Aflion of Fire, it necef- farily retains fome of the Particles thereof, which give it an acrimonious Tafte, that mere Earth could never have. — ■ From this Tafle it is called Salt ; and from its Pores being open, and thus difpofed to admit and imbibe new Acids, it is called Alkaly Salt. See Earth, Salt, gfc.

Now, it is not to be imagin'd, that an Earth which has once been impregnated with Acids, can ever be perfeftly di- verted thereof; there will flill remain fome, tho much lefs than before. So that an Alkaly may be conceived as only a too fmall Quantity of Acid, inclofed in too large a Quantity of Earth.

The vifible and fenfible Fire is not the only Agent capa- ble of feparating Acids from their Earth ; Fermentation has the fame Efteci, in virtue of that pure active Fire produced or concern'd therein. Alkalies, therefore, are the Produc- tion, either of the one, or the other Fire ; and the fame may be faid of the Acids difengag'd therefrom ; it being the Dif-union of the Parts of the fame Salt occafion'd by Fire, that yielded both the Acids as well as the Alkalies. All the Difference is, that the Alkaly imbibes and retains certain Corpufcles of the Fire, whereas nothing foreign is fuperadded to the Acid.

On this Principle every Acid is volatile, and every Alkaly JTiould be fix'd, if the Alkaly were only Earth : But, in re- gard the little Acid ftill remaining in the Alkaly, may be united with a Portion of Oil, as well as a Pottion'of Earth ; and Oil is known to be volatile ; the Compound, that is, the Alkaly, muft be volatile, in cafe the Oil prevail therein. In this Cafe, the Alkaly is found to have a ftrong, pene- trating, urinous Tafte and Smell ; and is what we call a Vo- latile urinous Alkaly Salt.

Thefe things well confider'd ; it will be eafy to affign „ what muft enfue upon the Separations, or new Unions of per Camp, the Parts of a Mixt. j t raav

An Acid, 'tis evident, may become an Alkaly, in that after having been feparated from its Matrix, it may be reftored in a fmall Quantity to another Matrix, either wholly earthy or earthy and oleaginous. — In the firft Cafe, it will become a Fix'd Alkaly ; in the fecond, it may be, a Volatile Alkaly, if in the fuppofed Matrix the Proportion of Oil prevail over that of Earth ; and in this Cafe it will be urinous.

Again, what before was a fix'd Alkaly, may become Vo- latile and Urinous, by depofiting or letting go part of its Earth, and taking Oil in its flead.

ALK

Thefe Tranfmutations are not found equally eafy and praflicable in the three different Kinds of Mixts or the three Kingdoms ; by reafon of the Diverfity of Circumftan- ces that muft concur thereto.— They are much the moll rare and difficult in the Mineral Realm ; by reafon, no doubt that the Parts of Minerals are more clofely ty'd together and have, as it were, lefs play. The only inftance B Chymiflry hath hitherto produced, of a Mineral Acid's being converted into a Fix'd Alkaly, is in the Operation of fixing Saltpetre.

The Vegetable Kingdom, it is obferv'd, furmiTies a large Quantity of fix'd Alkaly Salt ; and a little volatile Alkaly : The Animal Kingdom, on the contrary, affords a deal of volatile Alkaly Salt, and but little fix'd. The Foflil King- dom affords a very little native fix'd Alkaly Salt, as the Egyptian Natrum, and the Salts procured by Lotion from faline Earth about Smyrna and fome other Places of the Eafl ; and the Chymifts have alfo found a Method of con- verting Nitre into a fix'd Alkaly : But no body hath hitherto produced a volatile Alkaly from rhe Acids of the Mineral Kingdom.— And yet, if Acid Salts of the Vegetable Kind be convertible either into fixed or volatile Alkalies, why may not Mineral Acids be fufceptible of the fame Change ? fince Vegetable Acids are originally no other than Mineral ones : For, from whence but the Earth jhould Plants derive their acid Juice ?

In effefl, M. Geoffroy has at length fliewn the Operation feafable, by an actual Transformation of the fame Acid, Nitre, into a volatile urinous Alkaly. See the Mem. de (Acad, ubi fupra. See alfo Salt-petre, f$c.

By the way, it is to be noted, that the Inttance of Egyp- tian Natrum or Nitre, furnishes an Objection againft'the general Affertion of all Alkalies being artificial, or°produccd by Fire : Mr. "Boyle, who had fome of this Salt lent him by the EngliJJj Ambaffador at the Tone ; found that Vinegar would work brilkly on it, even in the Cold 5 " Whence, fays he, it appears, that the T' jptian Nitre, " acknowledged to be a native Salt, and mad? 'only by the " Evaporation of the fuperfluous Water of the Nile, is yet " of a lixivious Nature, or at leaft abounds with Particles " that are fo, tho produced without any precedent Incinera- " tion, and the Matter of it expofed to no Violence of the " Fire, to make it afford an Alkaly." Troducib. of Cbym.

frivcip. He adds, " However, he does not know any

" other Body in Nature, except this, wherein the Alkaline " Properties are not produced." Ibid.— And proceeds to give Inftances of Alkalies being made from Sea Salt, and other Acids ; and fticws, " how the fame Body, without " the Addition of any other Salt, may by varying the man- " net of the File's Application, be made cither to afford " little elfe than Acids, or a greater " kaly." Id. ibid.

For the Theory of the Operation of Acids upon Alkalies. See Acid.

1 greater or lefs Quantity of Al-

Hypothefis of Alkaly and Acid.

Tachenius, and Sylvius de la Soe, fbllow'd by the Tribe of vulgar Chymifts, ftrenuouliy affcrt Sal Alkaly and Acid to be the only univerfal Principles of all Bodies ; and by means heteof, account for the Qualities of Bodies, and the reft of the Phenomena of Nature ; particularly thole in the Animal Occonomy.— In a word, Alkaly and Acid are fubfti- tuted in the Head of Matter, and Motion. See Princi- ple, Element, ££c.

Mr. Soyle attacks this Hypothefis with great force of Ar- gument. — In effect, 'tis at bell but precarious to affirm, that Acid and Alkaline Parts are found in all Bodies.

When the Chymifts fee Aqua fortis diffolve Filings of Cop- per, they conclude, that the acid Spirits of the Menftruum meet in the Metal with an Alkaly, upon which they work 5 but how unfafe a way of arguing this is, appears hence, that Spirit of Urine, which is allowed a volatile Alkaly, and ac- cordingly makes a great Conflia with Aqua fortis, readily diffolves Filings of Copper, and more genuinely than the acid Liquor. — So, when they fee the Magiftery of Pearl or Coral, prepared by dropping Oil of Tartar into the Solu- tion of thofe Bodies made with Spirit of Vinegar ; they af- cribe the Precipitation to the fixed Alkaly of the Tartar, which mortifies the Acidity of the Spirit of Vinegar: where- as, the Precipitation would no lefs enfue, if, inftead of the alkalizate Oil of Tartar, that ftrong Acid, Oil of Sulphur ipanam, were ufed.

y alfo be doubted, whether it be juft to fuppofe, that when an Acid is difcover'd in a Body, the Operation of that Body on another, abounding with an Alkaly, muft be the Effe£c of a Conflia between thofe two Principles.*** For, an acid Body may do many things, not limply as an Acid, but on account of a Texture or Modification, which endows it with other Qualities as well as Acidity. Thus when the Chymifts fee an acid Menftruum, as Aqua fortis. Spirit of Salt, Oil of Vitriol, i$c. diffolve Iron, they ptefent- ly afcribe the Effea to an Acidity in the Liquors ; tho well dephlegmed urinous Spirits, which they hold to have a ■? eas

Ami.