Trocefs for exlraHing a Gum from Lichens. aqj 



And fuppofing too tables or preffes ufing gum, there would 



>e an nmn 



ual Paving of 45/. per table; or an annual faying" 

 of 22 /. 10 s. when gum fell to the peace-time priee or 

 7/. 10s. per ewt. 



Directions by Lord Dundonald for extracting Gum from tb$ 

 Lichen or Tree Mofs, &c. 



IT does not appear, from fueh trials as Lord Dundonald 

 has hitherto made, that there is any very great difference in 

 the produce of gum from the lichen collected from different 

 trees or (limbs: all of them anfwer equally well for yielding 

 a gum fit for calico printing. The lichen is mod: abundant 

 on the trees which grow in a poor, ftiffcl&y foil, particularly 

 if (ituated at fome confiderable height above fea level. It 

 fhould be pulled in dry weather, otherwife it is apt to break 

 in the pulling; befides, in this cafe, requiring to be dried 

 before it can with fafety be laid up in the ftorehoufe, where, 

 if put in dry, it may be kept for years. Should a iufneicnt 

 quantity of it not be found in this country, it may be had 

 in almoft unlimited abundance in Sweden, Norway, and m 

 the northern parts of America, where it grows to the length 

 of from a foot to eighteen inches, and preffing the branches 

 of the tree by its weight. There is, however, every reafon to 

 believe that a fufficient quantity is to be had in this country. 

 According to information from Dr. Brown, lecturer on bo- 

 tany, it takes three or four years in coming to maturity or 

 its full fize, fo that a crop from the fame tree may be had 

 every fourth year. 



The lichen does not confift entirely of a gummy matter. 

 There is the outer fkin or cuticle, below that a green refinous 

 matter: the remainder of the plant confjds of partly guru, 

 partly a matter fomevvhat analogous to animal fub fiances, 

 and a fmall proportion of fibrous matter, which cannot be 

 diflblved by boiling, or the action of alkaline falts. 



The tirft procefs in preparing gum from the lichen is to 

 free it of the outer (kin of the plant and the refinous matter. 

 This is done by fcalding the lichen two or three times with 

 boiling- water, allowing it to remain fo long in the water as, 

 by absorbing it, to fweil : in doing this the fkin cracks and 

 comes off along with the greateii part of the refinous matter. 

 Or it may be treed from them by gently boding the lichen 

 for about fifteen or twenty minutes, then warning it in cold 

 "water, laying it afterwards upon a ftone or brick floor, w here 

 it fhould lie for ten or twelve hours, or perhaps more. The 

 reafon for this is, that the expofure for that time to air 

 greatly facilitates the fubfequent extraction of the gum. 



4 The 



