150 
soluble animal or vegetable matters, if any exist in 
the soil. 
4. By the process of washing and filtration, the 
soil is separated into two portions, the most import- 
ant of which is generally the finely-divided matter. 
A minute analysis of the sand is seldom or never 
necessary, and its nature may be detected in the 
same manner as that of the stones or gravel. It is 
always either siliceous sand, or calcareous sand, 
or a mixture of both. If it consist wholly of 
carbonate of lime, it will be rapidly soluble in 
muriatic acid, with effervescence ; but if it consist 
partly of this substance, and partly of siliceous 
matter, the respective quantities may be ascertained 
by weighing the residuum after the action of the 
acid, which must be applied till the mixture has 
acquired a sour taste, and has ceased to effervesce. 
This residuum is the siliceous part ; it must be 
washed, dried, and heated strongly in a crucible ; 
the difference between the weight of it and the 
weight of the whole indicates the proportion of 
calcareous sand. 
5. The finely' divided matter of the soil is 
usually very compound in its nature ; it sometimes 
contains all the four primitive earths of soils, as 
well as animal and vegetable matter ; and to as- 
certain the proportions of these with tolerable ac- 
curacy is the most difficult part of the subject. 
The first process to be performed in this part of 
the analysis is the exposure of the fine matter of 
the soil to the action of muriatic acid. This sub- 
stance should be poured upon the earthy matter 
in an evaporating basin, in a quantity equal to 
