454 
Bones and Sulphuric Acid as Manures. 
Upon this ground — that the removal of the fat and gelatine 
facilitates the assimilation of the phosphate of the bone by the 
plant — alone can we explain the fact that dry bones can in any 
case be superior to fresh ones ; for nothing can afford us a 
shadow of a reason for saying that the animal matter of the bone 
is of no use to vegetation. On the contrary, we know that fat and 
oil, if extracted from the bone, and applied to the soil, act as 
potent manures, and that the gelatine is, in composition and effect, 
analogous to skin, wool, horn, &c., — substances which contain a 
greater supply of nitrogen, which they afford the plant in the 
shape of ammonia, than any other animal manures with which we 
are acquainted.* At the same time it is possible that, by being 
applied together, the fat may retard the decomposition of the 
gelatine, and render the phosphate less soluble, and thus, in some 
cases, injure the efficacy of the application for the turnip-crop — 
which is of a quick growth, and requires a ready food in its early 
stages. 
The whole case then stands thus: — Bones consist of two parts; 
one of animal matter, and one of earthy. Each of these, used 
separately, is a potent manure ; yet when both are used together 
the effect is in some cases less, in many not greater, than when the 
earthy part only is used — in fact, the part is equal to the whole. 
It is, however, known that when the two parts are combined, as in 
fresh bones, the earthy portion is very slow of decomposition, or 
change of form, and that the more this power of decomposition is 
encouraged by reducing the bone to powder, so as to admit moisture 
and those acids which dissolve the earthy part, and make it ready 
for absorption by the roots of the plant, the more efficacious is its 
action as a manure; hence the conclusion is apparent that the 
facility of decomposition is of great importance, and that, as the 
earthy part when apphed singly absoiljs water freelj and is easily 
soluble, it is this facility of decomposition, and the ready supply 
of phosphates which it gives the plant, that renders it capable of 
acting more efficaciously than when combined with a large amount 
of fertilizing animal matter — which matter has a tendency to 
diminish, or at least to retard, the supply of phosphates. 
Upon similar grounds we may explain the fact that boiled 
bones are so very generally jireferred to the fresh ones by the 
large turnip-growers, as they do not contain that fat which retards 
the decomposition. At the same time they still retain the gelatine 
which is so powerful an animal manure. So that while their phos- 
phates are rendered accessible to the plant by the fat being ex- 
* Wool, hair, and horn contain 16 per cent, of nitrogen, while farm 
manure does not aveiaije more than ^. The animal matter of bones con- 
tains more water than these substances, and it therefore decomposes more 
readily, and is more immediate in its effects. 
