134 
ON MANURE. 
soda will produce similar effects, but ammonia is to be preferred. Persons are a; 
to conclude, that to tliis brown colouring matter we must ascribe the nutritij 
qualities of liquid manures ; whereas, in fact, it is quite certain that not oii 
particle of the colour can enter the spongiolse of sound, undisturbed roots. i 
Now, if manure-water be weighed, and then gradually evaporated at a gen' 
heat, to dryness, the weight of colouring matter will be found to be very triflin'; 
and yet, gardeners are in the habit of adding much water to this liquid, consideri f 
it too strong for plants growing in pots. Having thus, by dilution, reduced t‘ 
tint to that of pale malt liquor, what activity can be expected from it ? Or jf 
such liquid manure be of any avail at all, to what material can we refer 5 
nutritive effects, since it is admitted that the particles of colour, minute as tli 
must be, are still too gross to enter the pores of the roots ? I 
To answer these queries by farther experiment, and thus gain a little mo 
light upon the subject, — let a few grains of powdered quicklime be stirred ii) 
the coloured fliuid and suffered to subside ; after a few minutes it will be seen tl i 
the colour of the liquid is lost ; that it has become quite pale ; while the sedimci 
itself has acquired a dingy brown tinge, and a flocculent texture. As a convej} 
of this experiment, let brown peat or black manure be worked up with one-thl 
the quantity of quicklime, and diluted with hot water suflflcient to allow of f| 
subsidence. After stirring from time to time, the compound matter will subsi| 
leaving the super -natant liquor nearly devoid of colour : — and now causj) 
ammonia may be added to excess, without effecting any change of tint, the lii) 
acting by more powerful affinity, and fixing the humic extractive in the fomf 
an insoluble humate of lime. 
In this way it is that lime acts as the specific reclaimer of waste and bari| 
peat-bogs, rendering them fertile by the abstraction and fixation of that inert al 
deleterious vegetable matter which is an antagonist to vegetation. And thus, ' 
an induction from undeniable chemical facts, we begin to perceive that we hs 
long been misled by crude theories and empirical practice. 
Liquid manures^ therefore, act by the salts which they contain, not by 1; 
colouring solution of humus ; and thus, also, we may be permitted to sanction lit 
cautious application of artificially prepared fluids, as for instance “ Potter’s Liqi|il 
Guano,” “ Humphreys’ Inodorous Compound,” and other fertilizers, which |3 
neither more nor less than solutions of chemical salts ; among the safest, and mil; 
effectual of which, are the sulphate of ammonia, nitrate of potassa (salt-petrjj, 
and sulphate of soda. 
Lime is the interpreter of this new and most intelligible theory ; for, by it 
important fact has been ascertained, that, for all the poisonous vegetable extractji 
peat-bogs, in old pastures, in gardens and soils over- glutted with manure, pt 
exerts the most powerful affinity, attracting the humic acid, not only from alkalis 
solutions, but from the body of the soil itself, fixing it in a condition of absolis 
insolubility, and thereby rendering the poison quite innocuous. 
