68 ON INCREASING THE GROWTH 



six or seven hundred-weight, in the state oi fine dust; 

 but at the present day, only one or two hundred- 

 weight, in a soluble (quickly operative) form, upon 

 the same surface ; and yet that by the latter incon- 

 siderable quantity the same result is now attained, 

 as in earlier times by from eight to ten times the 

 quantity of bones. The farmer who manures with 

 vitriolized bones (decomposed by sulphuric acid) is 

 accordingly able to reap from four to eight times 

 more land than formerly, with the same amount of 

 capital ; or what is the same thing, he can now ?lc- 

 complish as much with his money as in former times 

 with a capital from four to eight times larger. 



Composts whose action is quick and energetic will 

 not of course be persistent ; for if their constituents 

 are absorbed in the first year by plants, none can be 

 left for the following years. Uncalculating farmers 

 often urge this want of persistent or long-continued 

 action in quickly operative manures as an imperfec- 

 tion, while in other matters they admit the same 

 principle to be perfectly natural ; that the strength of 

 a galloping horse, for instance, is sooner expended 

 than that of a slow-pacing cart-horse, or that a quart 

 of oil is consumed more rapidly by a large solar, 

 than by a small kitchen lamp. A calculating farm- 

 er, on the contrary, will recognize at once that he 

 occupies a better position when the capital buried in 

 the land together with the interest can be recovered 

 in a year, than when a period of several years is 

 needed for this end. 



