173 



it is duly moistened, this carbon, in the same tempe- 

 rature, and under the same circumstances, is yielded 

 by the seed, and combines either with oxygen, ni- 

 trogen, or hydrogen gas. No other agent but hu- 

 midity, therefore, being introduced, to which this 

 variation in effect can be ascribed, we are led 

 to attribute it to that cause ; and to believe that 

 carbon, as it exists in seeds, may be so acted on or 

 dissolved by the imbibed water, as to be capable of 

 passing off from the seed with its exhaled moisture, 

 which thus becomes the proper vehicle of it. It is 

 well known, that both seeds and plants contain a 

 large portion of carbon, and it is extremely probable 

 that they derive it from a state of solution in water ; 

 for M. Giobert found, that plants did not grow well 

 in a mixture of simple earths until he moistened his 

 soil with water from a dunghill. Now it is certain, 

 from the experiments of Hassenfratz, says Dr 

 Thomson, that this water contains carbon j for 

 when evaporated, it constantly leaves behind a resi- 

 duum of charcoal. All those manures likewise 

 which act with efficacy and celerity, contain carbon 

 in such a state of combination, that it is soluble in 

 water ; and the efficacy of the manure is proportio- 

 nal to the quantity of carbon so soluble *. 



137. If then it be granted, that the carbon of de- 

 composing vegetables is largely soluble in water, there 

 seems no reason why the carbon of the seed, which 

 gradually diminishes (20.) during germination, 

 should not be soluble in it also : and since the wa- 



* Thomson's Chemistry, vol. iv. p. 253. 256. 



