180 QUARTERLY JOURNAL. 



If a farmer, without the guidance of just scientific principles, is trying experiments 

 to render a field fertile for a plant which it otherwise will not bear, his prospect of 

 success is very small. Thousands of farmers try such experiments in various direc- 

 tions, the result of which is a mass of practical experience forming a method of cul- 

 tivation which accomplishes the desired end for certain places; but the same method 

 frequently does not succeed— it indeed ceases to be applicable to a second or third 

 place in the immediate neighborhood. How large a capital, and how much power, 

 are wasted in these experiments ! Very different, and far more secure, is the path in- 

 dicated by science; it exposes us to no danger of failing, but, on the contrary, itfur- 

 nishes us with every guarantee of success. If the cause of failure — of barrenness in 

 the soil for one or two plants — has been discovered, means to remedy it may be 

 found. 



The most exact observations prove that the method of cultivation must vary with 

 the geognostical condition of the subsoil. In basalt, greywacke, porphyry, sand- 

 stone, limestone, &c., arc certain elements indispensable to the growth of plants, and 

 the presence of which renders them fertile. This fully explains the difference in the 

 necessary methods of culture for dilTerent places; since it is obvious that the essential 

 elements of the soil must vary with the varieties of composition of the rocks, from 

 the disintegration of which they originated. 



Wheat, clover, turnips, for example, each require certain elements from the soilf 

 they will not flourish Avhere the appropriate elements are absent. Science teaches u» 

 what elements are essential to every species of plants by an analysis of their ashes. 

 If therefore a soil is found wanting in any of those elements, we discover at once the 

 cause of its barrenness, and its removal may now be readily accomplished. 



The empiric attributes all his success to the mechanical operations of agriculture; 

 he experiences and recognises their value, without inquiring what are the causes Ofv 

 their utility, their mode of action: and yet this scientific knowledge is of thehighes 

 importance for regulating the application of power and the expenditure of capital— 

 for insuring its economical expenditure and the prevention of waste. Can it be 

 imagined that the mere passing of the ploughshare or the harrow through the soil— »a 

 the mere contact of the iron— can impart fertility miraculously? Nobody, perhapa^j 

 seriously entertains such an opinion. Nevertheless, the modus operandi of these me. 

 chanical operations is by no means generally understood. The fact is quite certain 

 that careful ploughing exerts the most favoaable influence; the surface is thus me.j 

 chanically divided, changed, increased, and renovated; but tlie ploughing is onlyJ 

 auxiliary to the end sought. 



In the effects of time, in what in agriculture are technically called/aWoirs — the re- 

 pose of the fields — we recognise by science certain chemical actions, which are con- 

 tinually exercised by the elements of the atmosphere upon the whole surface of our 

 globe. By the action of its oxygen and carbonic acid, aided by water, rain, changsg 

 of temperature, &c., certain elementary constituents of rocks, or of their ruins, 

 which form the soil capable of cultivation, are rendereil soluble in water, and conse- 

 quently become separable from all their insoluble parts. 



These chemical actions, poetically denominated "the tooth of time,'' destroy all 

 the works of man, and gradually reduce the hardest rocks to the condition of dust. 

 By their influence the necessary elements of the soil become fitted for assimilation 

 by plants; and it is precisely the enil which is obtained by the mechanical operations 

 of farming. They accellerate the decomposition of the soil, in order to j)rovidea 

 new generation of plants with the necessary elements in a condition favorable to 

 their assimilation. It is obvious that the rapidity of the decomposition of a solid 

 body must increase with the extension of its surface; the more points of contact we 

 offer in a given time to the external cuemical agent, the more rapid will be its ac- 

 tion. 



The chemist, in order to prepare a mineral for analysis, to decompose it, or to in- 



