VITRIOL. 



lev£i-al other parts of the khigdom. But all the vitriol 

 works have funk in value of late years ; the home confump- 

 tion of vitriol being much diminifhed, fmce the acid, which 

 ufed to be procured from the diftillation of vitriol, has been 

 obtained from the burning of fulphur. For the ancient and 

 modern method of obtaining this acid, we refer to the article 

 Sulphuric Acid. 



It is not eafy to determine when this method of making 

 vitriol was introduced into England. In the beginning of 

 the reign of queen Ehzabeth, a patent was granted to Cor- 

 nehus Devoz for making alum and copperas ; but it was 

 not till towards the end of the 17th century, that this art of 

 making vitriol was brought to fo great a perfeAion as to 

 enable us to export any of it ; and indeed Dr. Campbell 

 ( Surv. of Brit. vol. ii. p. 21.) affures us, that at tlie latter 

 end of the 17th century we imported annually about five 

 hundred tons of vitriol, and that we now export upwards of 

 two thoufaud tons. It appears from lir Charles Whit- 

 worth's Regifter of Trade, N^ i, that there were exported, 

 from the port of London alone, near four hundred tons of 

 copperas in three months, in 1776. A fmall quantity of 

 vitriol, perhaps to the annual amount of ii.*^ty or fixty tons, 

 fays Dr. Watfon, is ftill imported into England ; fome par- 

 ticular dyers, and other artifts, being of opinion, that the 

 foreign vitriol, as containing a little copper, is more ufeful 

 to them than the Englilh vitriol. It may be eafily known 

 whether green vitriol contains any copper, by only rubbing 

 the vitriol to be examined upon a moiftened piece of poli(hed 

 iron ; for if there is any copper in its compofition, the iron 

 will be changed into a copper colour. 



Vitriol is alfo prepared from mineral waters that hold 

 copper in folution, which is precipitated by iron : this folu- 

 tion of iron is afterwards cryftallized, and always retains 

 fome copper. In Hungary it is prepared from pyritaceous 

 fchillus, and in many places from a fpecies of calamine ; the 

 vitriol of Collar commonly contains a portion of zinc, as 

 that of Hungary and Saxony does of copper ; the Englifh 

 and French vitriols are purer, and yet fometimes contain a 

 fmall proportion of alum. Turt and peat are fometimes 

 impregnated with vitriol ; other earths alfo often contain 

 vitriol and alum. This vitriol is fometimes found of a white 

 colour, on the borders of the mineral lakes of Tufcany. 



Pure vitriol of iron is confiderably tranfparent, of a fine 

 bright, though not very deep, grafs-green colour ; of a 

 naufeous, aftringent tafte, accompanied with a kind of 

 fweetilhnefs. Difiblved, and fet to cryftallize, it flioots 

 into thick rhomboidal maffes, a part generally nfiiig at the 

 fame time in efBorefcences about the fides of the veffel. 

 Tlie folution depofits, in Handing, a confiderable quantity, 

 and in boiling a much larger one, of the metalhc bafis of 

 the vitriol, in form of a rufty calx or ochre : iron feems to 

 be the only metallic body that thus feparates fpontaneoufly, 

 in any confiderable quantity, from the vitriohc acid. On 

 expofing the vitriol itielf to a moift air, a fimilar refolution 

 happens on its furface ; which, fooner or later, according 

 as the acid is more or lefs faturated with the metal, changes 

 its green to a ruity hue. In a warm dry air, it lofes a part 

 of the phlegm or water, necefTary to its cryllalhne form, 

 and falls by degrees into a white powder. Expofed to a 

 gentle fire, it liquefies and boils up ; but foon changes, on 

 the exhalation of the watery part that rendered it fluid, to a 

 folid, opaque, whitifh, or grey mafs : this pulverized, and 

 Drged with a flronger fire, continues to emit fumes, becomes 

 yellow, being the •vitrwlum calcinaltim of the London and 

 Edinburgh Difpenfatories ; afterwards red, and at length 

 turns to a deep piirplilh-red calx, called colcolhar of •vitriol, 

 aiid the chalcitis jfaditia of the Paris Pharmacopoeia, revivable 



by inflammable fubftances into iron. This colcothar was 

 formerly fold at Paris for ten-pence a pound, and ufed for 

 giving the laft polifli to plate-glafs, at the great manufaAory 

 in the ftreet St. Antoine. The plate of glafs, when firft 

 caft, is an inch thick ; its afperities are ground away with a 

 coarfe kind of gi-it-ftone, with fand and emery, of different 

 degrees of finenefs, and it is at laft poliftied by colcothar. 

 Dr. Watfon fuggefted to the proprietors of the plate-glafs 

 manufaftory, near Prefcot, in Lancaihire, and to the pa- 

 tentees for polifliing marble, at Aftiford, in Derbyftiire, 

 that colcothar, which is very cheap, might perhaps render 

 the ufe of putty, or calcined tin, lefs neceffary. From the 

 colcothar of vitriol is prepared the ens -vsneru. 



From the green vitriol the vitriohc acid, now called ful- 

 phuric acid, has been generally extra&ed ; by diftilling the 

 calcined ritriol in earthen long necks, with a ftrong fire con- 

 tinued for two days or longer ; though it is now moftly ob- 

 tained by colleiting the vapour of burning fulphur. 



The diftiUcd fpirit appears of a dark blackilh colour, 

 and contains a quantity of phlegm, greater or lefs, according 

 as the vitriol has been lefs or more calcined. On committing 

 it a fecond time to diftillation, in a glafs retort placed in a 

 fand-heat, the phlegmatic parts rife firit, together with a 

 portion of the acid, and are kept apart under the name of 

 fpirit, or weak fpirit of vitriol, fpiritui vilrioH tenuis of the 

 London Difpenfatory : at the fame time, the remaining 

 Jirong fpirit, or oil, as it is called, lofes its black colour, 

 and becomes clear ; in which ftate it is the acidum vitriolicum 

 of the Edinburgh Difpenfatory, and the fpiritus vitriolifortis 

 of that of London ; and this is the ufual maiik for difcon~ 

 tinuing the redtification. 



The College of Edinburgh now direfts a weak vitriolic 

 acid of more certain itrength, made by mixing one part of 

 the ftrong acid with feven parts of water : this is called 

 acidum vitriolicum tenue, vulgo fpiritus vitrioli tenuis. See 

 Sulphuric Acid. 



Blue vitriol, or vitriol of copper, is commonly called 

 Roman or Cyprian vitriol, or blue-Hone. After being long 

 expofed to the air, it degenerates into a mixture of blue and 

 rufty yellow. It requires about four times its weight of 

 water to diflolve it in the temperature of 60^. Its fpecific 

 gravity is about 2.23. This fait rarely occurs cryftallized, 

 but is often found naturally diflblved in water, in Hungary, 

 Sweden, and Ireland ; from which water blue vitriol is 

 generally prepared, by evaporating the water to a proper 

 ftandard ; after which it is let out into coolers, where it 

 (hoots into regular and beautiful cryftals of a rhomboidal 

 form. See Zimext Water. 



It is alfo occafionally extracted from fulphurated copper 

 ores after torrefaftion, by the application of water, or 

 waflied out by rain or fubterraneous waters. Mr. Cronftedt 

 fays it is feldom free from iron and zinc. If a piece of 

 clean polifhed iron be dipped into the folution of this fait, 

 it will almoft immediately be covered with a cupreous coat : 

 this, together with the deep blue colour arifing from mixing 

 it with a volatile alkah, difcovers its bafis ; as its uniform 

 mixture with other vitriolic falts does its acid. Hence it 

 alfo appears, that the acid of vitriol has a greater affinity 

 with iron than with copper, becaufe it quits copper to unite 

 itfelf with iron. This faft explains, in a very fatisfaftory 

 manner, the nature of that tranfmutation of iron into copper, 

 which was formerly confidered as a perplexing phenomenon. 

 Agricola fpeaks of waters in the neighbourhood of Newfol, 

 in Hungary, which had the property of traiiimuting the 

 iron which was put into them into copper. In the year 

 1673, °'^'" countryman. Dr. Brown, vifited a famous copper- 

 mine at Herrn-Grundt, near Newfol ; and he informs us, 



that 



