AQUEOUS SOLUTION OF THE SOIL. 309 
years without perceptibly yielding aught of its mass to the 
liquid, does, nevertheless, slowly dissolve. We may make 
its solubility perceptible by a simple expedient. Pulver- 
ize the bottle to the finest dust, and thus extend the sur- 
face of glass many thousand or million times; weigh the 
glass-powder accurately, then agitate it for a few ininutes 
with water, remove the liquid, dry and weigh the glass 
again, We shall thus find that the glass has lost several 
per cent of its original weight (Pclouze), and by evapo- 
rating the water, it will leave a solid residue equal in 
weight to the loss experienced by the glass. 
g 2. . = 
AQUEOUS SOLUTION OF THE SOIL. 
The soil and the rocks from which it is formed would 
commonly be spoken of as insoluble in water. They are, 
however, soluble to a slight extent, or rather, we should 
say, they contain soluble matters. 
The quantity that water dissolves from a soil depends 
upon the amount of the liquid and the duration of its 
contact; it is therefore necessary, in order to estimate 
properly any statements respecting the solubility of the 
soil, to know the method and conditions of the experi- 
ment upon which such statements are based. 
We subjoin the results of various investigations that 
exhibit the general nature and amount of matters soluble. 
in water. 
In 1852 Verdeil and Risler examined 10 soils from the 
grounds of the Institut Agronomique, at Versailles. In 
each case about 22 Ibs. of the fine earth were mixed with 
pure lukewarm water to the consistence of a thin pap, 
and after standing several hours with frequent agitation 
the water was poured off; this process was repeated to 
the third time. The clear, faintly yellow solutions thus 
obtained were evaporated to dryness, and the residues 
were analyzed with results as follows, per cent:. 
