HOW PLANTS ABSORB CARBONIC ACID. 19 



the atmosphere. It is evident that this rose tree obtained its 

 Iced from the soil in which it was planted, and not from the at- 

 losphcre. It has been kept several months in this state, and I 

 (resume will flourish so long as it can be supplied with sustenance 

 rem the soil. 



1 I know not how others may construe the facts I have given ; 

 Tit I view them as conclusive evidence against the theory of Lie- 

 ig, " that the carbon of the plants is principally obtained by the 

 eaves absorbing carbonic gas." Nor do I consider the experiment 

 If Boussaingault as affording the least proof in favor of this theo- 

 ^j as the result would be the same whether the carbonic gas of 



: le atmosphere where taken up by the roots, or absorbed by the 



laves, Mr. B. must have known, I presume, that sea sand has 



?nerally more or less of broken shells in it, and that silicious sand 



mally contains about four per cent of carbonate of lime as one 



. 1" its components. 



Before quitting this subject I would suggest a new application 



those who keep greenhouses — one that I believe cannot fail to 



educe a very decided improvement in all their plants ; and as 



ie cost will be but rifling, I am confident will be applied by some 



;tiateur; and should the result answer my expectation, will soon 



universally employed. I would suggest that an apparatus be 



jaced immediately outside of the greenhouse to engender carbo- 



. n gas, that the gas be passed through a tube into the greenhouse 



( an evening after closing up for the night. Any vessel, either 



sme ware or metal, would answer the purpose, there being no 



isistance to the dr^ivery of the gas. Some machine can be placed 



aithe end of the tube, inside the house, like a ventilator, by which 



: ikns this ponderous gas could be thrown over the wLjle mass of 



. pints. It would be a cheap operation, as nothing but chalk or 



lliestone, and oil of vitriol water, would be required to engender 



;■ t* gas. In discussing this subject at a meeting of the Brooklyn 



; Ijtural History Society, our venerable president, Augustus Gra- 



■ Ip, Esq., suggested that the burning of charcoal inside the 



g!:enhouse might answer every purpose, and as this would be the 



'. nlst simple and least expensive, it would be well to give it a 



tid. 



"OL. II. — NO. I. G 



