[^54] 



By far the greateft proportion of vegetable fubftances confifts 

 of water ; according to Mr. Young and Ruckert grafs lofes 

 about I- of its weight on being dried into hay *. Dr. Hales 

 found a fun-flower plant, which weighed 48 ounces, to lofe 36 

 ounces by drying in the air during thirty days f , and confequently 

 to have loft | of its weight : even vegetables, to appearance 

 thoroughly dry, contain from | to i- of their weight of water |. 

 This water is not all in a liquid ftate, but by the lofs of much qf 

 its fpecific heat is in great meafure folidified. 



Of Coal, or the Carbonic Subjlance. 



To Mr. HafTenfraz we owe the difcovery, that coal is an 

 eflential ingredient in the food of all vegetables ; though 

 hitherto little attended to, it appears to be one of the primaeval 

 principles, as antient as the prefent conftitution of our globe : 

 for it is found in fixed air, of which it conftitutes above ^ part ; 

 and fixed air exifts in limeftones and other fubftances, which date 

 from the firft origin of things. 



Coal not only forms the refiduum of all vegetable fubftances, 

 that have undergone a flow and fmothercd combuftion, that is, 

 to which the free accefs of air has been prevented, but alfo 

 of all putrid vegetable and animal bodies ; hence it is found in 

 vegetable and animal manures that have undergone pvjtrefadion, 



and 



* 2d Young's An. 16. 2d. Ruckert 139. 



t ift Hales, 8. 



:|; Ruckert 28. Seneb. Encydop. Vegetation, 52. 



