340 Philosophy of Manures. 



formed in the earth by eremacausis, or the slow action of the 

 oxygen of the air; from its being soluble in such large quantity 

 in the water of the soil, aided by the absorbent powers of the 

 particles of soil themselves; from its known specific gravity, 

 inclining it to accumulate in greatest quantity at the surface of 

 the ground ; and from the action of every shower of rain in 

 washing all the gaseous substances of the air, soluble in water, 

 into the soil, carbonic acid should abound much more in the 

 soil than the air. All gaseous and fluid substances have a 

 tendency to mix together to a certain extent, from a weaker or 

 stronger affinity that they have for one another, though this 

 affinity may not always reach the amount of what is called 

 chemical. At the head of this list stands the affinity between 

 the oxygen and nitrogen of the air, which is still a matter of 

 dispute, whether chemical or not. Oil has a very slight affinity 

 for water, yetit may be mixed to a certain extent; but heat will 

 again lessen this weak affinity, and the lighter oil will swim on 

 the top. Agitation is sufficient to loosen some very weak affini- 

 ties. Carbonic acid has a pretty strong affinity for atmospheric 

 air, as it has been found on high mountains ; but this weak 

 affinity is liable to be disturbed both by heat and agitation. It 

 rises also very slowly in the atmosphere. In Mr. Dalton's ex- 

 periments, a phial of atmospheric air was inverted, with the 

 mouth open, over an open phial of carbonic acid, the external 

 air being excluded : at the end of one hour no trace of carbonic 

 acid was found in the upper phial, and it was three hours before 

 it could be said to be found to have arisen plentifully among 

 the atmospheric air. When the experiment is reversed, and 

 the air phial below, the carbonic acid goes to the bottom at 

 once ; and though hydrogen will go down through carbonic 

 acid, it is only from its superior affinity. On all these accounts, 

 and for the reasons stated in our former essay, on the supe- 

 rior growth of trees divested of their buds to those divested 

 of their fibres, &c., I still adhere to ray old-fashioned opinions, 

 till I can see better reasons for changing. 



Dr. Carpenter's opinions on the Causes of Reproduction or 

 fruitfulness in animals and plants are different from those of 

 Professor Liebig. The latter supposed it to be caused by 

 accumulation of nutriment. Dr. Carpenter supposes two anta- 

 gonist principles in living beings : one nutritive^ causing the 

 animal or plant to increase in bulk ; the other reproductive, 

 which begins to act only when the other has come to maturity; 

 and that this maturity is sooner arrived at in starved plants and 

 poorly fed people, who have generally more and healthier off- 

 spring than the rich. This opinion certainly agrees more with 

 observation than that of Dr. Liebig ; but the antagonist princi- 

 ples are only imaginary, and we see no reason why poverty 



