226 
INVESTIGATION OF SOILS. 
nents of all these soils can be eliminated and fairly exposed to "view with a minute- 
ness of precision which must ultimately lead to certain and fixed principles. It 
would, however, be too much to expect a practical gardener to attempt to operate 
for himself ; he must take much upon trust ; — but, nevertheless, it would be always 
advantageous to become acquainted with the theory of the analyst, and with the 
absolute facts which he can adduce. 
Formerly, in analysing a loam, the chemist was contented to determine its 
general earthy constituents, to search for and declare the amount of the rough sand, 
fine silex, alumina, carbonate of lime, and oxide of iron, which it might contain ; he 
sometimes alluded to the gypsum and phosphate of lime which were occasionally trace- 
able, and he could ascertain the weight of the organic substances that were com- 
bined with the earthy matters. But now, we are required to enter into an accuracy 
of detail concerning the neutral salts, and soluble extractive acids that are produced 
by simple boiling in pure distilled w T ater. A perfect loam, like the one described 
by Dr. Ure, in his article on Analysis of soil, (vol. v. part ii., of the Royal 
AgriculturalJournal,) and which "produced every variety of crop most abund- 
antly," and with only one manuring for fifty years, is not generally at command ; but 
every gardener may so modify his stores of turfy loam, (and these are notoriously 
required,) as to become representatives of such a soil, provided he comprehend the 
nature of the elements named, and the operation of tests by which they are to be 
detected. 
The table given by Dr. Ure is the following. It is capable of being imitated 
without much difficulty ; and if a large mass were properly prepared, it would 
furnish a store of loam that, for pot-culture, might last for many years. 
1 Silica, or fine flinty earth 56 0 per cent. 
2 Alumina 8 0 
3 Oxide of Iron . 5 5 
4 Carbonate of lime (chalk) 9 0 
5 Sub-phosphate of lime (bone earth) 0 4 
6 Carbonate of Magnesia . . . . . ..05 
7 Organic matter, chiefly vegetable mould . . . .66 
8 Moisture separable by steam heat . . . . ..113 
9 Do. separable at red-heat . . . . . .27 
100 0 
besides traces of muriate of soda, (common salt,) muriate of lime, and ammonia 
T W of a part, equivalent to 1 grain in 600 of the soil. This ammonia was 
obtained from the azotised organic matter of the loam, in which Guano, when pure, 
is so exceedingly rich. 
The tests required are caustic alkali, and nitric, or muriatic acid, to separate 
the silica ; caustic ammonia for the alumina, oxide of iron, and phosphate of 
lime ; oxalate of ammonia for the carbonate of lime ; and carbonate of soda, or 
phosphate of soda, for the magnesia. 
