CHEMICAL MANURES. 19 



ive labor; the day's work is then expressed by 4,320,000 pounds. 

 So, if we concentrate the labor of a horse for a day to one point, we 

 will say he raises 4,320,000 pounds to the height of 3i feet. 



But if one calorie equals 424 kilogrammetres or dynamic unities, 

 and if the combustion of 2 pounds of carbon produces 16,000 calories, 

 it results that 2 pounds of carbon correspond to 10,416,000 feet, or, in 

 round numbers, ,to one and a half day's labor of a horse, the day 

 being fixed at 'eight hours' effective work. 



By the light of these facts, which may seem far-fetched, but which 

 are necessary, the most hidden peculiarities of vegetable life will be 

 unveiled to us. 



The combustion of carbon engenders carbonic acid and produces 

 heat, which may be expressed by dynamic unities. If you should 

 attempt to turn back this current, and to undo what combustion has 

 done, to separate the carbon from the oxygen in carbonic acid, you 

 will not succeed, unless you return to the carbon and the oxygen a 

 quantity of heat equal to that born of their combination. 



This fact leads us to the following result : that every 2 pounds of 

 carbon which settles itself in vegetable matter requires 16,000 calo- 

 ries, equivalent to 10,416,000 feet, and they equal a day and a half 

 of a horse. Now, as the harvest of 1 acre may be fixed at 8888 

 pounds of vegetable matter, containing at least, and in round num- 

 bers, 4444 pounds of carbon, the settling of which has required 

 50,000,000 calories, we find that this quantity of heat corresponds 

 to 17 kilogrammetres that is, 6660 days' work of a horse. The 

 harvest of 1 acre is only obtained at this price. 



If, then, the preparation of 1 acre by the plough, the harrow, etc., 

 requires the same of a man as of a horse viz., 15 days' labor we see 

 that when man puts forth one mechanical effort, nature adds 444 by 

 the unostentatious means of light and heat. I 



But what is the source of this enormous consummation of forces 

 always in action and never exhausted ? You have already known 

 it : the rays of the sun, in whose absence plants cannot assimilate 

 carbon. If wood and vegetable products give out heat while burn- 

 ing, it is but what they have drawn from the sun, and which passes 

 by combustion from a latent state to a state of liberty. It is, in 

 reality, but an act of restitution. 



These explanations are sufficient, it seems to me, to demonstrate 

 the peculiar characteristics of vegetable products. 



I repeat that vegetation alone possesses the power of adding to the 

 first material used, which in all other cases is subject to waste, and 

 of giving a relatively enormous yield by the intervention of an un- 

 seen force. 



Here is shown the marvelous instinct of the people, who, outstrip- 

 ping science, recognize prosperity as durable only when founded on a 

 flourishing agriculture. It is for this reason that certain economists 

 of the last century, Quesney among others, conceived the idea of 

 laying taxes exclusively on the products of the soil, for it is they 

 only which yield an excess in the net produce. 



Gentlemen, you perhaps think I have let myself be drawn too far 



