156 
bination as muriates. The silica, after the usual 
process of lixiviation, must be heated red; the 
other substances may be separated in the same 
manner as from the muriatic and sulphuric so- 
lutions. 
This process is the one usually employed by 
chemical philosophers for the analysis of stones. 
8. If any saline matter, or soluble vegetable or 
animal matter is suspected in the soil, it will be 
found in the water of lixiviation used for separating 
the sand. 
This water must be evaporated to dryness in a 
proper dish, at a heat below its boiling point. 
If the solid matter obtained is of a brown colour 
and inflammable, it may be considered as partly 
vegetable extract. If its smell, when exposed to 
heat, be like that of burnt feathers, it contains 
animal or albuminous matter ; if it be white, crys- 
talline, and not destructible by heat, it may be 
considered as principally saline matter ; the nature 
of which may be known by the tests described 
page 106. 
9. Should sulphate or phosphate of lime be sus- 
pected in the entire soil, the detection of them 
requires a particular process upon it. A given 
weight of it, for instance, four hundred grains, 
must be heated red for half an hour in a crucible, 
mixed with one-third of powdered charcoal. The 
mixture must be boiled for a quarter of an hour, 
in a half pint of water, and the fluid collected 
through the filtre, and exposed for some days to 
the atmosphere in an open vessel. If any notable 
quantity of sulphate of lime (gypsum) existed in 
