52 LESSONS IN CHEMISTRY. 



we will therefore confine our attention, and endeavour to 

 trace, so far as the light of science can clearly point out, the 

 curious processes by which they are produced by the living 

 plant from the gases of the atmosphere and the materials of 

 the soil. Several of the substances to which I refer are 

 procured from plants for food and other purposes, and are 

 well known to every farmer. 



60. If we proceed to examine any of our food-yielding 

 plants, or the uncultivated tribes of the roadside or the 

 mountain, we can, by a little care, make ourselves acquainted 

 with their composition. 



If we place in a Florence oil-flask some shavings of wood, 

 and boil them successively in spirits of wine and water, con- 

 tinuing the boiling with each Hquid so long as it dissolves 

 anything, we will at last procure a white fibrous substance 

 insoluble in water, and which has neither smell nor taste. 

 This substance is termed woody fibre, and forms the bulk of 

 the greater number of plants. The fibre of the Flax plant, 

 which is so valuable for manufacturing purposes, and to pro- 

 cure which of good quality is the great object of the flax- 

 growers of Ulster, consists of woody fibre united with a small 

 portion of matters derived from the soil. It has been found 

 that this woody matter of plants is chiefly composed of a 

 peculiar substance to which the name of cellular fihre is 

 usually given, and which is regarded as the earliest foi-med 

 portion of their structure. In the development of the vegetable 

 kingdom, cellular fibre is the chief building material employed. 

 It can, by chemical means, be procured from all the parts of 

 plants, and as prepared from the fibre of cotton it was found 

 by a celebrated French chemist, who has particularly studied 

 this subject, to possess the following composition : — 



Carbon . . . 44-35 

 Hydrogen . . 6*14 



Oxygen . . .49*51 



100 



It is curious to observe that in cellular fibre, no matter 

 from what plant derived, whether from the spongy rush or 

 the firm oak, the hydrogen and oxygen exist in the same 

 proportions in which these gases unite to form water; that is, 

 one part of hydrogen is combined with eight parts of oxygen. 



