18 CHEMICAL MANURES. 



Composition of Wheat (Straw and Grain). 



In 100 parts. 



Carbon .................... 47.69 ") T T ^ 



Hvdrosren 5 54 (- * ere ' 93 ' 5 ' 5 come * rom tlie air an(i 



oxygen.. ::::::::::::::::4o:32 j tlie rain - 



Soda ...................... 0.09 1 



Magnesia ................... 0.20 



Sulphuric acid .......... 0.31 Here, 3.386, with which the soil is 



Chlorine .................. 0.03 [-abundantly supplied, and which we 



Oxide of iron 0.006 



need not give to it. 



Silica 2.75 



Manganese (?) 



Phfsphoric r aci'd:.'.'.'.'.'.'.'. 045 1, Here, 3.00, with which the soU is 

 p ota gh QQ > but poorly provided, and we must give 



Lime..'''''''.'.'.'.'.'.'.'.'.'.''.'' QJ29 J to U b ^ manures - 

 "99^3 ' 



We will now pass to a second characteristic of agricultural pro- 

 duction, although of the same order as the preceding, yet more dim- 

 cult to understand. 



Until the last twenty years we believed that the phenomena of 

 nature were due to different causes, because they affected different 

 organs in ourselves. 



Under this impression of diversity a more perfect analysis ended 

 by discovering that this multiplicity of causes was but apparent, and 

 that in reality all physical phenomena are the result of a sole cause 

 motion. 



Let us follow the consequences of this fundamental cause. You 

 all know that the combustion of a body is followed by an elevation 

 of temperature. For example, the combustion of 2 pounds of carbon 

 produces heat enough to raise 16,000 pounds of water one degree. 

 If I add that which we call the quantity of heat necessary to raise 

 2 pounds of water one degree calorie, we may say that the combus- 

 tion of 2 pounds of carbon produces 16,000 calories. 



You know that mechanical force is engendered by heat. There is 

 an immutable correlation between the weight of the body burned, the 

 temperature produced and the force made by it. 



We know that one calorie equals a force sufficient to raise a weight 

 of 2 pounds to the height of 1389 feet, and we call the force necessary 

 to raise 2 pounds to the height of 3 feet 3 inches a kilogrammetre, 

 or a dynamic unity. 



It follows, then, that one calorie, or the quantity of heat which will 

 raise 2 pounds of water one degree, is sufficient to raise the same 2 

 pounds 1389 feet high or, in other words, 1 calorie is equivalent to 

 424 kilogrammetres. 



Let us follow the results of these facts. The work of a horse in 

 harness is expressed by 540,000 pounds the hour that is to say, that 

 the efforts he puts forth will raise 540,000 pounds to the height of 3 

 feet per hour. We estimate the day of a horse at eight hours' effect- 



