83

which may convey some proportion of theother ingredient. The same observation holdsalso with respect to sand. Thus we have seen,in the last chapter, a clayey loam, in which thesandy ingredient was defective, and the argil-laceous superabundant, but the calcareous ex-act. Its composition stood thus:

Sand and Gravel - - - 47

Argill.22

Mild Calx.,31

Here the sandy part wants 10 per cwt. theargill is superabundant ; but we cannot increasethe proportion of sand without diminishing thatof calx. Hence we must either use a smallerproportion of the sandy ingredient than its de-fect requires, or apply a substance that wouldsupply some proportion of the calcareous in-gredient also: such are limestone-gravel, sili-cious marl, effete lime, mixed with sand, orpounded limestone. Suppose the proportionof the substance to be employed were six percwt.; that is, six pound for every hundredpounds of the soil, then the quantity requisiteG 2