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twice the weight of the earthy matter ; but diluted 
with double its volume of water. The mixture 
should be often stirred, and suffered to remain for 
an hour, or an hour and a half, before it is ex- 
amined. 
If any carbonate of lime or of magnesia exist in 
the soil, they will have been dissolved in this time 
by the acid, which sometimes takes up likewise 
a little oxide of iron ; but very seldom any 
alumina. 
The fluid should be passed through a filtre ; the 
solid matter collected, washed with rain water, 
dried at a moderate heat, and weighed. Its loss 
will denote the quantity of solid matter taken up. 
The washings must be added to the solution, which, 
if not sour to the taste, must be made so by the 
addition of fresh acid, when a little solution of 
prussiate of potassa and iron must be mixed with 
the whole. If a blue precipitate occurs, it denotes 
the presence of oxide of iron, and the solution of 
the prussiate must be dropped in till no farther 
elfect is produced. To ascertain its quantity, it 
must be collected in the same manner as other 
solid precipitates, and heated red ; the result is 
oxide of iron, which may be mixed with a little 
oxide of manganesum. 
Into the fluid freed from oxide of iron, a solu- 
tion of neutralized carbonate of potash must be 
poured, till all effervescence ceases in it, and till its 
taste and smell indicate a considerable excess of 
alkaline salt. 
The precipitate that falls down is carbonate of 
l 4 
