130 Messrs Edwards and Colin upon the 



of Carbonic acid. Of the 55 centilitres produced by the expe- 

 riment of five days' continuance in summer, 48 were carbonic 

 acid. 2dly, An infinitely small quantity, 2.5 millilitres was 

 oxygen, and about 3.5 centilitres, which appeared to be nitro- 

 gen. In short, there was, 1st, an enormous quantity of car- 

 bonic acid ; 2dly, scarcely any oxygen ; and, 3dly, a quantity 

 of gas, which, in the mean while, we shall regard as formed 

 entirely of nitrogen, and which amounted to somewhat less 

 than the quantity of air contained in the water. On another 

 occasion, we shall consider whether any other gas was present. 



Whence, then, proceeded this enormous quantity of carbonic 

 acid, in the production of wliich the air contained in the 

 water must be counted for nothing ? It is clear, that since 

 the oxygen does not proceed from the air dissolved in the 

 water, it must be derived from one of the elements of the 

 water itself. The water, therefore, is decomposed ; the oxy- 

 gen, one of its elements, unites itself to the carbon of the 

 seed, and forms the carbonic acid which disengages itself in 

 whole or in part ; a question into which we shall enter upon 

 another opportunity. 



It now remains to inquire what becomes of the hydrogen, 

 the other element of the water ? We suppose, for the mo- 

 ment, that there is no trace of it, as we have stated provi- 

 sionally above ; and since it is not disengaged, it must evi- 

 dently be absorbed by the seed. 



Hence, the results which follow from the experiments which 

 we have detailed, from seeds placed in the conditions stated, 

 are, 1st, that the water is decomposed ; 2d, that the oxygen 

 of the decomposed portion, unites -with the carbon of the 

 seed, and forms carbonic acid gas ; 3d, that this carbonic acid 

 disengages itself from the seed, in whole or in part ; and 

 4thly, the other portion of the decomposed water, the hydro- 

 gen, is absorbed by the seed, in whole or in part. These 

 are the four fundamental propositions regarding the respira- 

 tion of seeds, to which we shall confine ourselves on the pre- 

 sent occasion. 



It is not a matter of very great moment to ascertain whe- 

 ther all the carbonic acid is completely disengaged. Nor 

 is it of more consequence that we should know at present 



