C 94 ] 



The volatile oils have never been used as articles 

 of food ; many of them are employed in the arts, in 

 the manufacture of pigments and varnish ; but their 

 most extensive application is as perfumes. 



17 Woody fibre is procured from the wood, bark, 

 leaves, or flowers of trees, by exposing them to the 

 repeated action of boiling water and boiling alcohol. 

 It is the insoluble matter that remains, and is the basis 

 of the solid organised parts of plants. There are as 

 many varieties of woody fibre as there are plants and 

 organs of plants ; but they are all distinguished by 

 their fibrous texture, and their insolubility. 



Woody fibre burns with a yellow flame, and pro- 

 duces water and carbonic acid in burning When it 

 is distilled in close vessels, it yields a considerable 

 residuum of charcoal. It is from woody fibre, indeed, 

 that charcoal is procured for the purposes of life. 



The following table contains the results of expe- 

 riments made by Mr. Mushet, on the quantity of char- 

 coal afforded by different wood. 

 10O parts of Lignum Vitas - 26,8 of charcoal 



Mahogany - 25,4 



Laburnum - 24,5 



Chesnut - - 23,2 



Oak 22,6 



American black Beech 2 1 ,4 



- Walnut - 20,6 



Holly - 19,9 



Beech 19,9 



American Maple 1 9,9 



Elm - 19,5 



