Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/726

 V I T

V I T

tfiol or copperas in the pyrites with us in England. That Stone is well known to contain fulphur and iron, both in large quantity ; and the combination of thefe in the earth, or in the air, where moifture enough can get at them, may very well be underftood to form Vitriol, which is the natural re- fult of fuch a folution. Phil. Tranf. N°. 104. It is obfervable, that before metallic Vitriols are difletved in water, they cannot be perfectly dried without changing their nature; and when diflblved, they conftantly let tall much ochre to the bottom ; fo that by repeated folution and cryftal- lization of Vitriol in water, all the Vitriol is at length turned into ochre, and an unctuous liquor, that cannot eafily be dried. Whence the eafier, the quicker, and with the lefs wa- ter, fomc falts are diflblved, the more eafily they retain their water.

There is alfo fomething particular in the folution of metals by water, for certain falts are required to diflblve them; and when they are diflblved into cryftals of Vitriol, they then rea- dily and eafily diflblve in water, fo long as thefe cryftals re- tain that fait which is the folvent of.the metal ; but when this faline folvent is wanting in the Vitriols, water will fcarce dif- folve them at all, but fuffers the metallic part to precipitate ; but when the metal is previoufly diflblved by its own folvent fait, it readily yields to water, and may thus, by a gentle evaporation, be reduced to cryftals, wherein the metal, its fol- vent, and water always concur in a certain proportion. By this method metals are made potable, and act: in the body as well, according to the acid folvent, as to the nature of the metal diflblved. The action of all Vitriols depends thus upon thefe two principles united with water ; and of' this kind are the Vitriols of gold, filver, copper, iron, lead, and tin. This rule does not extend, however, to all the Vitriols ; for thofe of the femi-metals, though they are firft diflblved by their acid folvents, fo as to appear in a faline form, cannot therefore be diluted with water like the falts of the true me- tals : Thus pure regulus of antimony, perfectly diflblved in fpirit of fea-falt, adhering to the mercury fublimate, in the di- stillation of the butter of antimony, is a true Vitriol compofed ofantimony, diflblved in fpirit of fea-falt : Whence one might SuSpect, that it would diflblve in water ; but, on the con- trary, as foon as water touches it, the acid folvent quits the regulus, mixes with the water, and lets fall the metallic calx entire. Boerhaave, Chem. part 1. p. 451. Liquamen Pyritieum, or mother of Vitriol, is of an acrid and firey tafte, very different from that of Vitriol, and has been proved by fome late experiments, to contain a fait very dif- ferent from the Vitriol. The method of Separating this pure, is _to evaporate a quantity of the water, impregnated with Vitriol, and received from the beds of the pyrites ; this being evaporated to a pellicle, the Vitriol will fhoot in the cold, and a quantity of ochre will be precipitated. After this, fuc- cceding evaporations will yield more Vitriol and more ochre, to the fifth time ; but if the experiment be continued after this, the firft Succeeding fhooting of the liquor yields, inftead of Vitriol, a yellow fait.

This contains the laft portion of the ochre remaining in the liquor. After this, the matter yielding no more Vitriol, k called the wafh, or Liquamen of Vitriol. It taftes acrid and firey, and the quantity left from a gallon of the well impreg- nated liquor from the bed, is about a pound. From this may be procured a white pungent fait, by fubfequent evaporations. This is the faline principle of Vitriol, according to the chc- mifts, and is contained in fo large a quantity, that near thirteen ounces of it may be Separated from a pound of the liquor ; the remaining liquor, after this, is what is called Liquamen Vitriol: by fome chemifts, but not properly. It will never coagulate into fait, but is very firy and acrid to the tafte, and ex- tremely ponderous, not lefs fo than oil of Vitriol, nor lefs pungent; and is the ftrongeft liquor any way obtained from a natural fubftance without diftillation. This liquor being expofed to the air in a veflel not clofed, will in a little time attraa double its weight of water from it. All corrofive and fahne liquors havefomewhat of this property of imbibing moi- flure from the air, and weakening themfelves by it ; but this liquor attracts it fafter and in greater quantily than any other- This liquor receives moft moifture, and inceafes moft quickly in wet weather, lefs fo in dry; and this may have given occafion to that error fo common among the chemifls that feveral preparations of Vitriol derive moifture from the moon, and have more or lefs of it, according to her different phafes. The changes of the conftitution of the air have ef- fected what, in this cafe, they fuppofed to be done bv the different phafes of the moon. Phil. Tranf. N°. 103.- ' Vitriol of Copper. Theglafs-makershavs a method of mak- ing this without corrofives, which was originally practifed by Neri, and with which they make fome very fine colours in glaSs, particularly a fine fea-green.

The method of making the preparation is this : Take little thin pieces of brafs, and lay them Jlratumfuper jlratum in a

. crucible, with powder of brimftone. When the veflel is full, fet it luted and covered in an open wind furnace, with burn- ing coals over it, and let it ftand two hours ; then let the fur- nace cool of itfelf, and take out the crucible, the mafs within

. will be of an obfeure bbckifh purple ; powder and fift it fine,

and then mixing with every pound of it fix ounces of powdered brimftone, take a round veflel of earth, that will bear the fire, place it upon iron bars fet acrofs in an open wind fur- nace, fill-it with coals, and then put in the powder ; keep it burning and ftirring about till all the brimftone is burnt up; then take out the pan, and powder the calcined mafs again - fift it fine, and proceed with it thrice as before ; the laft time let it ftand on the fire till it become red. Put a pound of this calcined copper into a glais body, with fix pints of water • evaporate two pints or thereabout in a fand heat ; the water is then of a fine blue, and mult be poured off clear ; then fil- trate it. Evaporate the water from the remaining fediment of copper left in the glafs, and with new fulphur calcine it again and again ; repeat this five or fix times, and extract the blue tincture with water as before ; filtrate all the waters, and put them together. Evaporate all to a fifth part or thereabouts, and fet it in a cool place, and fine pointed cryftals will be formed, refembling emeralds; feparate thefe cryftals, and evaporate the water again, till all the cryftals be procured. Then put a pound of them into a glafs retort, well luted and fitted to a capacious receiver; let the joints be well clofed, and make a moderate fire for four hours ; then make it vio- lent for twenty hours, or till no more white fumes arife. The next day open the receiver, and feparate the liquor into a glafs, where it muff be kept carefully fealed up, Neri's "Art of Glafs, p. 50.

Very great things are to be done in the glafs art by means of this liquor ; the remainder in the retort expofed to the air for a few days, will acquire a blue colour, and this, mixed with zaffer, will give glafs a fine fea-green.

White Vitriol. It has been difputed whether white Vitriol is any thing elfe than green Vitriol calcined. But it feems that white Vitriol is of a quite different fpecies from either the green or the blue Vitriols. See Geoffroy. Mat. Med. Tom. 1. p. 124.

in the condition in which white Vitriol is ufually bought, it contains fomewhat both of copper and iron ; but, being puri- fied by folution, filtration and cry flail izat ion, it is freed from both thefe metals, and appears to be a native Vitriol Jul gene- ris. Sec Cramer, Elem. Art. Docim. vol. I. p. 302. ed. 2. Med. Eft". Edinb. Abr, vol. 2. p. 472. If four ounces of alum be put in concoction with two parts of cadmia fojfilis pulverized, the earth of the alum precipitates, and its acid takes hold of the earth of zinc, fo that a true white Vitriol is the refult.

This*Vitriol being precipitated by an alkaline lye, and dried, after its falts are Separated in water, and then mixed with charcoal-duft, it will give zinc, in the manner mentioned under the article Zinc.

The fame thing happens in mixing Vitriol of iron with two or three parts of lapis calaminaris ; but the operation is eafier with alum and Vitriol of copper. Marggraf in Mem. de 1'Acad. de Berlin, 1746.

Blue Vitriol is made by evaporating ziment-water to a pro- per ftandard ; after which it is let out into coolers, where it Shoots into regular and beautiful cryftals of a rbomboidal form, and compofed of ten planes. Thefe have the fame .qualities with the water ; and being diflblved in common wa- ter, they make a ziinent liquor, undittinguifliable from the native kind. See the article Ziment-^W. Blue Vitriol is alfo contained in fury or rufma, and many of the pyritse and marcafites or mundics, but Seldom, pure. There are alfo fome earths which contain it, but they prin- cipally owe it to ziment-waters pafling through them. Blue Vitriol has copper for its bafis, and is never ufed inter- nally, but only in external applications. There are feveral preparations of it recommended in difpenfotories, the moft va- luable of which feems to be the aqua Vitriolica cerulea. See the article Aqua.

Vi t r i o l of Quickfilver, the name of a chemical preparation of quickfilver, with acid fpirits, the proceSs of which ts this : Let fo rich a Solution of quickfilver be made in fpirit of nitre, or aqua-fortis, that no more can be contained ; let this Solution be made by the affiftance of heat, and the liquor immediately afterwards poured oft' into a clean and cold glafs. There will, on this, fpontaneoufly fhoot on the bottom of the glafs a faline white tranfparent matter, from which the liquor being poured, it is found to be a {harp moift faline fubftance, or true Vitriol of mercury, foluble in water, and not fafe to be touched : If the liquor, poured off from this, be evaporated half away, and the remainder fet in a cool place, more cryftals of the fame nature with the firft will fhoot.

Another method of making the Vitriol of mercury, is this : Reduce to powder fome defcrepitated fea-falt, and with two parts of this mix one part of crude mercury; diftil the whole in a glafs body, with a Strong fire, continued for five or fix hours ; when the veflels are cold, break them, and there will be found a folid dry mercury, Sublimed to the top and fides of the body, in form of Vitriol ; Nay, Boerhaave affirms, that the common mercury fublimate is a true Vitriol of mercury, though fern i- volatile! Boerh. Chem. part 2. p. 301. Preparations of Vitriol are, 1. The acid fpirit, or oil of Vitriol. 2. Colcothar, or calcined Vitriol. 3 Tartarian Vi- triolatunu 4. Spt'ritus Vitrioli dulcis. 5, The compound

triolatum.