486 



is, during the time decay goes on with the greatest rapidity, 

 more than this excess of carbonic acid would be taken up by 

 the leaves of plants during their rapid growth. In winter, 

 when little carbonic acid is produced, in consequence of the 

 process of decay being slow, all would be carried away in 

 solution by the rains. In autumn only should we be likely 

 to find a greater amount of this gas in extensive woodland 

 districts than in the open country ; but as this is not even 

 found to increase the amount so much as to enable us with 

 certainty to detect it, and can never be equal to that pro- 

 duced from the combustion of fuel in large manufacturing 

 towns, we cannot assign any injurious tendency to its presence. 



We must not, in fact, look to the natural process of decay 

 for any thing prejudicial to the existence of life; it is a 

 process ordained by an all-wise Providence to insure and 

 maintain its existence. By it, dead and otherwise useless 

 matters are converted into compounds useful in supporting 

 the life of plants, and forming food for man ; and by thus 

 effecting a continued transmutation of matter from a state of 

 death to life, it insures that uniformity in the earth's surface 

 and in our atmosphere which appears so necessary to the 

 existence of organized beings. It is a process, therefore, 

 which, if allowed to go on with that regularity with which 

 it was intended, and which does now go on in those healthy 

 districts not yet over-crowded or polluted by the negligence 

 of man, would still maintain the atmosphere in that uniform 

 salutary state in which it formerly existed. 



We must search among the products arising from those 

 heaps of putrefying animal and vegetable remains, which, 

 from being saturated with moisture, prevent all access of 

 atmospheric air, and will not allow the natural process of 

 decay to go on. Here we shall find not only compounds 

 produced of an entirely difi'erent character to those generated 

 by decay, but compounds the nature of which varies with 



