ANALYSIS OF SOILS. 169 
difference; tlis will give its porosity or power of 
absorption. Now add water till the tube is nearly 
full, and shake the whole well up—the soil should 
occupy about one-third of the tube, and place it in 
a perpendicular position to settle. It will be then 
observed that it hus arranged itself in the order of 
the specific gravity of each component part of the 
soil: the coarsest sand will be found at the bottom, 
and the finest impalpable powder at the top—the lat- 
ter is its most valuable constituent. 
Care must be observed in selecting the soils for 
these experiments—several samples of the same sort at 
distances from each other must be taken an inch or 
two under the actual surface; these should. be well 
mixed together, and the quantity to be weighed taken 
from it. 
I think it would scarcely be within the limits of 
this small treatise to go further into the matter of 
density, proportions of clay ana sand, and the finer 
analysis; the formule will be found in Johnstone’s 
Analysis of Soils and his Lectures on Agricultural 
Chemistry, to which I would refer my readers who 
are interested on any further investigations. 
_ ROUGH METHOD OF ESTIMATING BY QUANTI. 
TATIVE ANALYSIS THE POTASH AND 
PHOSPHORIC ACID CONTAINED IN SOILS. 
This paper was drawn up by Dr. Koch, of the 
Colonial Medical Department, at our request. In for- 
warding it he wrote :— 
“My own idea is that this kind of testing cannot 
be done successfully, but by those who have studied 
the subject carefully. 
“The specimen of soil for examination must be 
well pulverized and thoroughly dried in the sun. 
Weigh 100 grains and digest it for an hour or two 
in pure hydrochloric acid. The mixture is then to be 
gently boiled for about half an hour, and filtered 
through blotting paper; wash the residue with boiling 
distilled water. The filtrate and washings will now 
contain the alkalies and alkaline earths in the form 
of chlorides, Add a few drops of nitric acid to the 
clear solution, and gently warm the mixture. After 
cooling add an excess of solution of ammonia and 
sesquicarbonate of ammonia. This will cause the separa- 
tion of all the iron, aluminum, and a portion of the 
lime and magnesia in the soil. Filter again and add 
to the clear liquid a solution of oxalate of ammonia. 
This will remove all the lime in the form of a white 
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