LIC 741 LIC 



ed in a bsth compossd of the water in which the lichen these salts, half an English pint of liquid ammonia. Lichen. 



The boiling is continued until the liquor acquire a con- S """Y~ 111 " 



had been boiletl for half an hour, with the addition of 

 tome common salt, acquired a fine and brilliant gold- 



siderable degree of gummy consistence. It is then ta- 



yellow colour. I. Westringii possesses qualities of still ken out of the boiler, and allowed to drain througha 

 higher character, and seems to be superior in tinging wire-cloth. The residuum may be put into a hair-cloth 



properties to orchal itself; but it is unfortunately a rare 

 specie*. It may be enough, therefore, to mention, thnt 

 it yielded a rich orange colour, which was brightened 

 by the addition of muriate of cobalt. Porina pertusa 

 yielded a brown colour; and Lecanora ventosa com- 

 municated to wool the same colour, possessed of so 

 much fixity that it resisted the action of alkalies. Le- 

 canora hartnatomma, (Lichen coccineus of Dickson,) a 

 psjciM which occurs plentifully on the well known 

 Stonehenge pillars, afforded only a wax-yellow colour, 

 notwithstanding the bright red of the tubercles. In 

 l>r Wearing'* hands, Lecanora tartarea, or the prin- 

 cipal cudbear lichen, yielded to wool a rich puce brown ; 

 and it wa* only by the addition of a solution of tin, that 

 be procured a brownish red, which, however, was ve- 

 ry beautiful. Of the imbricated lichens he examined 

 the qualities of a good many species, chiefly belonging 

 to the genus Parmelia of Acharius. P. saxatilis, alrea- 

 dy noticed as still employed in some parts of Scotland 

 for dyeing wool, gave with soda a yellow colour ; with 

 lime and sal-ammoniac, a nankeen ; and with com- 

 mon sal and nitre, an orange. P. physodes, which 

 grows abundantly on trunks of trees, and on stones in 

 woods, in this country, he found to be very rich in co- 

 louring matter, affording, by means of the same re- 

 agents, tints varying from a citron yellow to chestnut 

 brown. It deserve* notice, that P. tygia yielded, in 

 hit experiments, a yellowish colour only, and no red 

 or violet, which preceding writers had ascribed to it. 

 Solorina crocea, although of a saffron-yellow aspect, 

 when treated in the usual way with quicklime and 

 sal-ammoniac, gave out a red colour. This species, 

 as already noticed, occurs on the Scottish mountains, 

 but probably nowhere in sufficient quantity to render 

 it an object of importance. 



One of the projects of the ingenious Lord Dundonald 

 was to introduce the employment of the mucilage of 

 Lichen* for thickening the mordants, and fixing the co- 

 lours in calico-printing. His Lordship remarks, that 

 lichens (meaning chiefly the branched tree-lichens, but 

 without determining accurately the particular species) 

 are composed of different substances. There is the 

 outer skin or cuticle ; below that, a green resinous mat- 

 ter : the remainder of the plant consists partly of gum, 

 partly of* matter somewhat analogous to animal sub- 

 stances, and a vmall proportion of fibrous matter, which 

 is not dissolved by boiling, or by the action of alkaline 

 salts. The irst process in preparing the mucilage is 

 to detach the outer skin, and the resinous matter. This 

 u done by scalding two or three times with boiling 

 water, allowing the lichen to remain so long in the wa- 

 ter as, by absorbing it, to swell ; for, in swelling, the 

 skin crack*, and comes off, along with the greater part 

 of the resinous matter. Or the same thing is accom- 

 plished by gently boiling the lichen for a quarter of an 

 hour, then washing it in cold water, and spreading it 

 a floor of brick or stone for half a day. An ad- 

 eason for this last practice is, that the expo- 

 to the air greatly facilitate* the subsequent extrac- 

 tion of the gum. The scalded lichen is then put into 

 a cant-iron boiler, with water in the proportion of two 

 wine gallon* to every pound of lichen, and boiled dur- 

 ing four or five hours, adding about half an ounce of po- 

 UM or of soda for every pound of lichen ; or, instead of 



upon 



bag, and squeezed in a press similar to that used by 

 tallow-chandlers. The first boiling, however, by no 

 means extracts the whole of the gum. The lichen is 

 boiled a second or even a third time, repeating the pro- 

 cess above described, and diminishing each time the 

 quantity of water and of alkali added. When three 

 boilings are employed, the gummy extract of the last 

 may with propriety be reserved for the first boiling of 

 a fresh batch of lichen. The extract proceeding from 

 the first and second boilings is mixed together, and 

 evaporated to the consistence necessary for block or 

 press printing. The evaporating vessels are of tin or 

 thin lead, placed over a range of stoves, and moderate- 

 ly heated, which is best done by steam. The muci- 

 lage thus procured is more or less coloured ; but Lord 

 Dundonald remarked, that, by continuing the digestion 

 longer, with a low degree of heat, and abstaining from 

 the use of any alkali, it might be produced nearly free 

 of colour. It appears, indeed, from the experiments of 

 M. Georgi, professor of chemistry at St. Petersburgh, 

 that several of the lichens which have already been 

 mentioned, (particularly Ramalina farinacea and Par- 

 melia phj sodes,) form with water a mucilage which 

 yields, when evaporated, a gum as transparent as gum 

 arabic, and in the proportion of about an eighth of 

 the weight of the lichen. M. Amoreux repeated and 

 extended the experiments of Georgi, and obtained con- 

 siderable portions of pure gum from many of the broad- 

 leaved lichens, such as Peltidea canina, Ramalina f'rax. 

 inea, and Parmelia capcrata. All the lichens now men- 

 tioned are common in this country ; and the two spe- 

 cies of liamalina, in particular, might be collected from 

 trees in many woods and orchards, in great plenty and 

 in great purity. 



See Philosophical Transactions for 1758, (Watson); 

 Memoirs of lite Academy of Sciences of Lyons, for 1786', 

 (WiUemet) ; Amoreux Kecherches el Experiences stir 

 divers Lichens; Memoirs of the Stockholm Academy, 

 from 1702 to 1799; Crell's 'Annals for 1796, 1797, and 

 1799- and Annettes de Chimie, vols. xv. and xvii. (West- 

 ring;) Journal de Physique, vol. Ixiii. (Proust;) Phi- 

 losop/i'cal Magazine, vol. x. (Dundonald.) (p. N.) 



LICHFIELD, or LITCHFIELD, is an ancient city of 

 England, in Staffordshire, and, united with Coventry, 

 is the see of a bishop. It is situated on a small river 

 running into the Trent, almost in the centre of Eng- 

 land, in a healthy and agreeable valley, surrounded by 

 hills of moderate height. The town is divided by a 

 large and fine sheet of water into two parts, the city 

 and the close ; and consists of three or four good streets, 

 with several smaller ones. The principal streets are 

 Bridge street, vulgarly Bird street, Beacon or Bacon 

 street, and St. John street, running off from this last in 

 a southern direction. The high road from Birmingham 

 to Newcaatle-under-Lyne passes through the principal 

 street. Many of the houses in Lichfield are elegant 

 and well built ; but several of them are constructed in 

 the ancient style. 



The principal public building in Lichfield is the ca- 

 thedra], situated in the Close, and beside the sheet of 

 water already mentioned. It is supposed to have been 

 built about the year 667, during the bishopric of Jura- 

 man. It was rebuilt in 700 by bishop Headda, who 

 dedicated it to St. Chad, and removed his bones to 



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