li 3 



LIBRATION. 



LICHENS. 



251 



to booksellers and printers, the volume is one that could much less 

 easily be spared than many of higher pretensions ; and keeps a place on 

 the shelves of those who are fond of anecdote and the bye-ways of 

 information, side by side with Hone's ' Every Day Book.' A volume on 

 libraries on the same easy plan as Timperley's on printing, would be a 

 very acceptable addition to our literature. The only separate book on 

 the subject at present, is Mr. Edwards's * Memoirs on Libraries ' 

 2 vola., 1859, a work more ambitious but less useful, and less attractive, 

 and in which it is remarkable how little the writer gives from personal 

 observation, and how much from printed statements of mere detail, 

 even in cases such as those of the history of the libraries of 

 London and Manchester, in which both sources of information must 

 have been open to him. With all their deficiencies, however, these 

 volumes are, till some similar work shall supersede them, an indis- 

 pensable companion to the inquirer into the history and statistics cf 

 libraries. 



LimiATION, a balancing motion, in which there is a position on 

 one side and the other of which a body vibrates ; being in fact the 

 same in meaning as oscillation. This term is however particularly 

 applied to a small irregularity, compounded of the moon's rotation 

 round her axis and her orbital motion, by means of which her visible 

 hemisphere is not always quite the same. 



The mean revolution of the moon round her axis is the same period 

 of time as her mean revolution in her orbit. If both motions were 

 equable the moon would always present the same face to a spectator 

 placed at the centre of the earth, on condition that the plane of her 

 equator passed through the centre of the earth. None of these con- 

 ditions being exactly fulfilled, and the variations being small and 

 periodic, the consequence ia that a small portion of the moon's surface 

 in the eastern and western edges, and also in the northern and southern, 

 is alternately visible and invisible. There is perhaps no subject in 

 astronomy BO difficult to explain to a reader who is not familiar with 

 polid geometry ; and the subject is not of sufficient importance to 

 o any detail of illustration. 



LICENTIATE IN MEDICINE. [PHYSICIANS, COLLEGE or.] 



LK'KENIC ACID, a name given by Pfaff to an acid extracted by 

 him from Iceland moss, but which has since been proved to be identical 

 with fuinaric acid. [FuMARic ACID.] 



Lli '!! IAIN (G',,0 10 H 10 ), is a variety of starch found in the Lichen 

 iilantiicut, or Iceland moss. It is colourless and tasteless, swelling up 

 into a jelly-like mass in cold water, and dissolving in hot. Its solution 

 Coloured blue by iodine. It is converted into sugar by diluted 

 and boiling sulphuric acid. Hot dilute nitric acid converts it into 

 oxalic 



Ll< 'II EXS, C<J<'r in:/ matten of. The lichens or liverworts, as they 

 arc frequently termed, constitute a large class of perennial plants. 

 They are common in nearly all countries, growing on rocks, stones, 

 trunks of trees, &c., and in appearance are very insignificant. They 

 vary considerably in colour and size, but generally so much resemble 

 the bark or earth to which they are attached, and over which they 

 i , that a somewhat close inspection is necessary before they are 

 observed. Unimportant as they appear to be, however, it is greatly to 

 their agency that we owe those magnificent lilac, blue, violet, purple, 

 any intermediate and compound colours with which wool and 

 ailk are dyed. 



The English lichens are not much used for the manufacture of dyes, 

 though were a system for their collection organised, it would probably 

 ind that many varieties might be economically employed. 

 Foreign lichens to the extent of 90,000?. worth are annually imported 

 into this country from the south of Europe and west coast of America, 

 but chiefly from (the Canary Islands. They Ate principally collected 

 from rocks in the 'neighbourhood of the sea. 



Lichens do not contain in their natural state any colouring matter 



ready formed, but under the influence of air, water, ammonia, and a 



i ite temperature, certain acids and a neutral body existing in 



them are converted into a deep richly-coloured substance called orcein. 



1 1 U the dark purple or red matter that is finally produced under 



tlie above circumstances, but its formation is sufficiently gradual to 



admit of the process being arrested at any desired stage, and the tint 



if nut the actual colour of the product thus varied at will. On these 



conditions, and on the dexterous mixture of the products with each 



other depends the shade of the resulting pigment, and not on the use 



>y particular variety of lichen. A skilful manufacturer will 



<;e a given colour from any or all of the lichens, his only anxiety 



to use that variety which contains the largest per-centage of 



colorific material. 



The lichen colours are sent out by the maker either in the dry state, 



lump or powder, as a strong solution, or as a paste, conditions severally 



nmtod to the uses to which they are applied. The details 



necessary to be observed in the production of these various forms of 



!<>urare giren in the respective articles ou each. Hee ARCHIL; 



KAB; LITJH 



HMll'in nf the value of lic/ieim. Lichens vary considerably in the 

 amount of colour-producing substance contained in them. The fol- 

 lowing process, proposed by Stenhoiise, in very easy of application, and 

 gives accurate relative results. It is founded on the reaction of chloride 

 .f lime upon the colorific agent, a fugitive red colour being thereby 

 produced. A givuii weight of the lichen reduced to powder in a mortar, 



or to a pulp with water, is digested in thin milk of lime, and the 

 mixture filtered ; a standard solution of chloride of lime is now added 

 in small quantities at a time, fresh portions being poured in as soon As 

 the red colour produced by the previous portion has disappeared, the 

 addition being discontinued when no more colour is produced. The 

 relative value of several samples can thus be very quickly determined, 

 or the strength of the standard solution being known, the absolute 

 amount of colouring matter is clearly indicated. 



As already stated, orcein is the colouring substance ultimately 

 resulting from the treatment of lichens for the preparation of archil, 

 &c. Now the body from which orcein is derived is a colourless 

 matter, named orcin. Orcin exists ready formed in some of the lichens, 

 but its chief source is certain acid matters contained in all varieties of 

 the plant. Under the influence of alkalies these acids are converted 

 ir.';j orcin, and into secondary acids. The primary lichen acids admit 

 of being readily extracted, and Stenhouse has proposed that the opera- 

 tion be performed upon the lichens as soon as gathered, the storage, 

 freightage, &c.> of a great quantity of useless material being thereby 

 obviated. The process recommended by that chemist consists in 

 placing the lichens in wooden barrels, which are to be filled up with 

 water containing a quantity of slaked lime, allowing the whole to stand 

 a short time, then drawing off the liquor and saturating it with common 

 hydrochloric acid. In this way the lichen acids are dissolved out by 

 the lime, but are re-precipitated by the hydrochloric acid, and after 

 collecting on a filter may be drained, dried, and packed in casks for 

 transit. This proposal, however, has not been adopted, or if adopted 

 has not been persisted in ; perhaps the ready-formed orcin occurs to a 

 larger extent in the lichens than has been supposed, and not being 

 precipitated from solution by hydrochloric acid, would be lost if the 

 whole lichen were not acted upon. 



A rough assay of lichens for colouring matter may be made by going 

 through the above process on the small scale, a known weight of tho 

 lichen being taken, and the precipitated acids being dried at 212 Fahr. 

 and weighed. 



A list of the lichens used in the production of pigments, and a 

 woodcut illustrating their general appearance, will be found under 

 LICIIKXS, in NAT. HIST. Div. 



The acid and other bodies derived from the lichens are numerous, 

 and as a whole have formed the subject of elaborate investigations by 

 Stenhouse and Schunck. Their relations to each other, however, are 

 at present not very well ascertained ; and although Gerhardt has pro- 

 posed formulae calculated from the analyses and the provisional empi- 

 rical formulse given by the chemists who have examined them, he 

 admits that those formulas still require verification, and indicates that 

 fact by placing a note of interrogation after the formuke. 



The following is a list of the lichen derivatives : 



. C SO II 8 0, (?) 

 C, 8 H lc o,,(!) 



C 30 lt, 6 I .(?) 



C,,H M U (!) 



. C 16 H 8 8 (!) 



. C 1( H,0 I2 (?j 

 . C la II a 8 (!) 



1. Chryeophanic acid . . 



2. Usnic acid 



3. Erjthric acid . 



4. Erythrolltc acid. 



5. ticroerythrin . 

 G. Erythro-mannite 



7. Nitro-erythro-mannite . 



8. Lecahoric acid i 



9. Orsellle acid . 



10. Pscuderythrin . ; 



11. Amarythrin. 



12. Telcry till-in . . ; 



13. I'artllic acid . . . 



14. noccellinin . 



15. Evcrnie acid I . ; 

 1C. Gyrophoric acid. 



17. Evertllnic acid C 18 ll 10 b 8 (!) 



IS. Orcin C 14 il,O 4 +2Aq. 



19. Orcein C 14 U,N0 8 (!) 



20. Leuoorctin. 



21. Chlororcein. 



22. AzoerythHn. 



53. Erythroldc abld (erytlxralcin ?) 

 2-1. Litmic acid (azolitmin !) 



25. Litmylic acid (erythrolitmin ?) 



26. Spaniulitmin. 



27; Deta-orcln I I I Cj,H 10 O4 



1. Chrtnophanic acid; VulpMc toeiil. This acid is contained in 

 wolves' lichen (Evernia vulpina), in yellow moss (Parmelia pufietina), 

 as well as in the different varieties of rhubarb, [CIIRYSOPHANIC 

 ACID.] 



2. Usnic bcid ; Usncin ; Piirietin. This body is obtained on treating 

 the Jupiter's-beardj Tree-beard, and other hair-like members of the 

 Usnea genus of lichens, with thin milk of lime, in the manner already 

 described; The precipitated acid may be obtained in crystals from 

 solution in warm (but not boiling) alcohol. Alkaliei convert it into 



