Soluble vs. Insoluble Cane Manures. 335 
On the disadvantages of ammoniacal salts and super 
phosphate as manures. The principal objection to be 
urged against the use of ammonia and its compounds as a 
source of nitrogen is the great loss that must result from 
drainage. As this loss comes about in an indirect way 
that has only been elucidated of late years some explana- 
tion concerning it may not be superfluous. In 1845 H- 
S. THOMSON observed that when water containing sul- 
phate or carbonate of ammonium in solution is filtered 
through a layer of soil, the portion that has passed through 
contains scarcely any of the ammoniacal compound, the 
remainder having been absorbed or fixed by the soil. 
Professor Way subsequently found that the salts, sul- 
phate, nitrate and chloride of ammonium in solution in 
water, were all decomposed by the soil, and gave up 
their ammonia to it completely, whilst the acid (whe- 
ther sulphuric, nitric or hydrochloric) which was in com- 
bination with the ammonia, united with other bases 
(usually the lime and magnesia present in the soil), form- 
ing soluble salts that filtered through. Phosphoric acid 
was not affected in the same manner as the other acids, 
but, like ammonia, was retained by the soil, so that if 
phosphate of ammonium were used in the experiment, 
no part of that salt, either acid or base, would pass out 
in the drainage. Potash also was retained- The func- 
tion of arresting and retaining the valuable manurial 
materials, ammonia, potash and phosphoric acid is pos- 
sessed in a greater or less degree by all soils, and, at 
all events in the case of ammonia and potash, appears 
to depend chiefly on the organic or humus substances 
present, which exert an attractive power on those bases 
usually likened to that exercised by animal charcoal, 
