2a8 On exlraS'ing Gum/mm the Lichett, 



Direliions for extraSling Gum from the Lichen, or Tree Mojs-, bfc. By tht Earl Of 



JLT does not appear from fuch 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 {hrubs : all of them anfwef equally well for yielding a gum fit for calico 

 printing. The lichen is mofl: abundant on the trees which grow in a poor, ftiff clay foil, 

 particularly if fituated at fome confiderable height above fea- level. It ftiould 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 (torehoufe, where, if put in dry, it 

 may be kept for years. Should a fuflicient quantity of it not be found in this country, k 

 may be had in almoft unlimited abundance in Sweden, Norway, and in the northern parts 

 of America, where it grows to the length of from a foot to eighteen inches, depreffmg 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 botany, it takes three or four years in coming to maturity or its full fize, fio 

 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 Ikin or 

 cuticle, below that a green refinous matter: the remainder of the plant confifts of partly 

 gum, partly a matter fomewhat analogous to animal fubftances, and a fmall proportion of 

 fibrous matter, which cannot be diffolved by boiling, or the action of alkaline falts. 



The firft procefs in preparing gum from the lichen is to free it of the outer flcin of ths 

 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 abforbing it to fwell ; in 

 doing this the Ikin cracks and comes off along with the greateft part of the refinous matter. 

 Or it may be freed from them by gently boiling the lichen for about fifteen or twenty 

 minutes, then wafliing it in cold water, laying it afterwards upon a flone or brick floor, 

 where it (hould 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 extraftion of the gum. 



The fcalded lichen is then to be put into a copper boiler, with a due proportion of 

 water, fay three Scotch pints, or two winp gallons,, to every pound of lichen, and boiled 



• Early in the prefent year this Nobleman convened the calico printers of Scotland, and comraimicated 

 to them this important difcovery, at a meeting at Glafgow, where feveral refolutions were made for the pur- 

 pofe of fecuring its advantages to thc' country, with a proper reward to the inventor. The prefent paper 

 was printed at Glafgow, in fix pages duodecimo, 1801. The ftatement which follows was alfo drawn up 

 by his Lordfliip, by whom 1 was, favouied wiih bo,tlv. 



during 



