96 
It cannot be doubted that the volatile oils con- 
sist of carbon, hydrogene, and oxygene ; but 
no accurate experiments have as yet been made 
on the proportions in which these^ elements are 
combined. 
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 varnishes ; but 
their most extensive application is as perfumes. 
17. Woody fibre is procured from 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 organized 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 consider- 
able 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 ex- 
periments made by Mr. Mushet, on the quantity 
of charcoal afforded by different wood. 
100 parts of Lignum Vitae - - 26,8 of charcoal 
Mahogany - - 25,4 
■ — Laburnum - - 24,5 
Chesnut - - 25,2 
— — Oak - - - 22,6 
■ — — American black Beech 21,4 
