55 



them artificially, at such periods as it may be necessary, 

 or desirable, to accelerate their growth, and induce a more 

 perfect and mature developement. It has been already 

 stated, that the most important of these aeriform bodies, 

 are nitrogen, which plants derive from ammonia ; and 

 carbon, which they derive from carbonic acid gas, on the 

 liberation of the oxygen, which is one of its constituents ; 

 neither of these, can however be appropaiated, when in 

 a free state, but only when in a state of combination, and 

 forming either a gaseous or a fluid body. It is probable 

 that nitrogen might be supplied to plants, through the 

 medium of the atmosphere in an artificial manner, by 

 placing within any structure, a portion of some of the 

 volatile salts of ammonia, which latter being given oif, 

 would at once supply the demands of vegetation. Car- 

 bon might be applied, by the use of charcoal ; and it is 

 worthy of experiment how far the combustion of charcoal, 

 in plant structures, by accelerating the formation of car- 

 bonic acid gas, may have a beneficial influence on vege- 

 tation. The use of charcoal as an ingredient in the soil, 

 though doubtless partly, and perhaps principally mecha- 

 nical, is nevertheless in all probability rendered advan- 

 tageous in this very way; the slowness of its decompo- 

 sition must however render the quantity applied, very 

 homoeopathic in its nature. 



A series of experiments with the view of ascertaining 

 the practicability of continually supplying to the atmos- 

 phere, those qualities which plants abstract from it, and 

 of determining the manner, and the degree in which they 

 should be applied, would be one of the most interesting 

 and important matters, to which the minds of Horticul- 

 tural reformers could possibly be directed; but it is most 

 essential, to remember, at the same time, " that these 

 are powerful agents, requiring much skill in their adap- 

 tation," and capable of effecting serious injury and dis- 

 appointment, if indiscriminately applied. 



