346 Timehri. 
the plant, and their nitrogen being more or less insoluble 
is not so liable to waste ; moreover, much of the excess 
not utilised by one crop may be counted on to remain in 
the soil to furnish nitrogen to subsequent ones* Dried 
blood contains almost as much nitrogen (about 14 per 
cent.) as nitrate of sodium (15^ per cent.) and in cer r 
tain cases has a6ted as energetically. About half the 
nitrogen present in it is in the form of compounds soluble 
in water, the remainder being insoluble, but still capable 
of being easily converted into plant food. Flesh meal 
also contains about 14 per cent, of nitrogen, chiefly in 
an insoluble, but readily available form. The various 
oil cakes contain 4 to 5 per cent, of nitrogen ; earth 
nut cake being about the richest, whilst hemp seed cake 
is said to a6t quickly, and linseed cake slowly. Mixed 
with an equal weight of slaked lime to cause more rapid 
decomposition, they should prove useful manures for 
soils deficient in organic matter, especially for burnt 
soil, which no doubt might be readily restored to fer- 
tility by their use. The nitrogen present in such sub- 
stances, ought to be obtained at a lower price than that 
present in nitrates, or ammonia salts, so that if it proved 
to be equally efficient, a considerable saving not only 
from waste, but also in cost might be effected by their 
use. 
* " In addition to the nitrogen removed in the crop, and to that lost 
by drainage, some small proportion is found by analysis to be retained 
in the soil itself. The nitrogen may be of advantage to crops grown 
subsequently, according to the source from which it is derived ; for 
while ammonia salts and nitrates yield but very small residues, and 
exert but little or no effeft beyond the first year, from bones, cake, and 
other such materials we get large residues of nitrogen in the soil, which 
tell markedly on future crops." Dr. Voelcker in Enclycopcedia 
Britannica. Last Edit. Art. Manure. 
