46 :^ QUARTERLY JOURNAL. 



acorn, from which sprung the oak that is now our admiration, ger 

 minated a hundred years ago, the soil where it fell, did not con 

 tain the millionth part of the charcoal which the oak now incloses 

 It is the carbonic acid of the atmosphere which has furnished a' 

 the rest ; that is to say, almost the whole mass of the noble tree. 



" But what can be more clear or conclusive upon this subjec 

 than the experiment of M. Boussaingault, in which peas sown i 

 sand, watered with distilled water, and fed by the air alone, nevei 

 theless found in this air all the carbon necessary to their develoj 

 ment, flowering and fructification." 



" If then the plant is vegetating in a soil which furnishes n 

 carbonic acid to the roots, the whole supply must he derived fro', 

 the atmosphere by its leaves J^ 



I believe that Mr. Liebig is in error in supposing that the leave 

 by absorbing carbonic acid, supply trees or other vegetables wil 

 the principal portion of their carbon. I shall offer some fact 

 which I think will go far to disprove this assertion. 



I am aware that it is up-hill work to call in question any theoi 

 of Liebig's, for so great is the confidence of his readers in h 

 opinions, that it is considered mere querulousness to call any 

 them in question. 



I am also aware that my own positions may be erroneous. C 

 this point, I have only one request to make, that any error I m: 

 fall into, may be shown, not merely asserted ; and if the objectio; 

 are well founded, I will readily acknowledge the error. 



Man is a theoretical being, and those who can produce the mo 

 splendid and imposing theories, are sure to stand on the pinnae 

 of literary fame. It is of little consequence whether the hypoth 

 sis on which a theory is raised be well founded or not, provided 

 be specious, for few men are capable of testing it by the touchstot 

 of truth ; and it is so much easier to believe than to investigat 

 that any thing, however absurd, when supported with talent, wi, 

 be sure to meet with a competent number of proselytes. • 



We look with contempt on the theories of past centuries, whi 

 we are deeply absorbed in those of the present day, which in the, 

 turn will become the objects of disproof by succeeding generations 

 but theories, like governments, will some of them leave a splend 

 train in their rear, whilst others will be thrown down and forgottf 

 almost as soon as they are formed. 



