356 



or phosphate, as named above, or as a carbonate, and as this 

 carbonate is found in abundance in all fertile soils, no one 

 could ascribe the failure of the red clover crop to this. Ex- 

 perience, however, tells us that the application of lime has 

 an important influence on the growth and development of the 

 clover plant, whether it be red or white, and this on soils 

 where analysis shows the presence of considerable quantities 

 of carbonate of lime; the lime, then, when applied in a 

 caustic state, must exert some chemical action on the con- 

 stituents of the soil, and thereby act beneficially to the plant, 

 for it would shortly become a carbonate when mixed with 

 the soil, and consequently only increase the quantity of an 

 ingredient which is already present in abundance. The soils 

 I have submitted to analysis contain more than two tons of 

 carbonate of lime per acre, a great part of which has been 

 added to them artificially in the shape of Derbyshire lime ; 

 this would probably be a means of preventing the failure 

 of the clover crop when first applied, for reasons I shall 

 presently assign. Magnesia is contained here in such 

 minute portions, that it is next to impossible to detect it 

 by analysis ; and although it would probably have little 

 influence on the failure or success of the clover, yet its 

 absence would undoubtedly be a source of injury to such 

 plants as require it in abundance. The deficiency of mag- 

 nesia cannot be the cause of failure in this case, as the soil 

 where the clover was perfected contained no more than that 

 where it failed. 



Iron and manganese are contained in such minute propor- 

 tions in this and other plants, that they may be looked upon 

 rather as accidental than as necessary constituents. I shall 

 not, consequently, take any account of them in this essay ; 

 we shall, however, next come to a substance which, of all 

 others, is the most important of the fixed constituents of 

 plants, namely, potash. 



