LICHEN ISLANDICUS. 7S9 



moss as much as 70 per cent, of the so-called Lichenin or Lichen-starch, 

 a body which is perfectly devoid of structure. The decoction (1 : 20) 

 gelatinizes on cooling, and assumes a reddish or bluish tint by solution 

 of iodine. This property of lichenin is plainly seen, when the drug is 

 first exhausted by boiling spirit of wine containing some carbonate of 

 potassium ; and then boiled with 50 to 100 parts of water, and the decoc- 

 tion precipitated by means of alcohol. The lichenin thus obtained in a 

 purer state, must be deprived of alcohol by cautiously washing it with 

 water. Powdered iodine will now immediately impart to it while still 

 moist an intense blue. Its composition, C'WV, agrees with that of 

 starch and cellulose ; and it must be regarded as a modification of the 

 latter, being likewise soluble in water and in aramoniacal solution of 

 copper. Lichenin is not a kind of mucilage, because it yields _but 

 insignificant traces of mucic acid, if treated with concentrated mtric 

 acid ; and also because it contains no inorganic constituents. The very 

 trifling proportion of mucic acid it furnishes may depend upon the 

 presence, in small amount, of an independent mucilaginous body. 



According to Th. Bero- (1873), lichenin consists of what he coutmues 

 to call so, and another constituent, the latter only being coloured by 

 iodine, possessing (dextrogyre) rotatory power, and also being insoluble 

 in ammoniacal solution of copper. Berg's lichenin is not soluble m coia 

 ^^ater, but readily dissolves in hot water, and again separates on cooiin . 

 The other constituent on the contrary is abundantly soluble mcold 

 and very sparingly in hot water. The drug yielded to Berg .0 per cent. 

 of " true " lichenin and 10 per cent, of the other f ^^^^^^,^- , j -^ ^Ij 



The chlorophyll of the gonidia is not soluble in ^yf^^^™^^^^^ 

 and hence is distinguished by Knop and Schnedermann as ThalloUdor. 



Its quantity is extremely small. ^ , . ..;j ^„ Cpfmrin, 



^Jhe bitter principle of Cetraria, called C^^^™""/!?! let cold 

 C''H-0», crys Jlizes in n^icroscopic needles, xs n^f ly nsolub e m ccj 



jyater> and irms ^vith alkalis, yellow easily f '^^e, ^ f /fp'eculiar 

 lichen also contains a little sugar, and about 1 per ce"^^^. ^ ^ j^ ^t 

 Jody, Licheno-.tearic Acid, C^H'^O', t^e.crystals of wh^jh 

 20° C. The Lich^nnc AcicUoxmA by Pfaff m 1826 n l^^^^^;^.^^ 

 iormerly regarded as a peculiar compound, has been pro 

 with fumaric acid. . .. QmUc A cid and is 



.In common with many lichens, cetraria ««"*^;"' ^h^mounts to 1-2 

 said to yield also some tartaric acid, l^^e ash -w^ en ^^^^ined 



P^y cent., consists to the extent of two-faflhs of silicic 

 chiefly with potash and lime. collected in many 



,. Collection and Commerce-Iceland moss i«^^ ^ .^ g^^^^^^ 

 districts where the plant abounds at least loi loc _^ ^^^^ gathered in 

 Whence some is shipped to other countries ^ Lucerne, and 



Switzerland, especially on the mountains of the Canton 

 in Spain.^ None is exported from Iceland. ^^^^.^^^ ^^..^^ ^^^ 



Uses— It is given in decoction as a miW jou - ^^^^^ ^^^ only in 

 active medicines It is very little emploj^ed in ^.^^^ ^.^^ ^1^^ 



seasons of scarcity, when it is sometimes giouno 



. T, . . ,, » cat. of SpanUn Proiuciions,-l.u^on 



