ON MANURE. 
133 
immediate attention being the application of liquid manure ; a practice which 
appears to extend with great rapidity. In looking over the weekly publications 
on horticulture, we cannot but be struck with the earnest recommendations of 
fluid manures ; and as it is more than probable that they who look for correct 
information in such publications, will attach faith to the advice they there meet 
with, it becomes a duty to investigate the principles upon which this practice is 
founded. 
Mr. Knight, of Downton, was perhaps the first person of authority to whose 
advocacy we may ascribe the introduction of liquid manure : he employed pigeons' 
dung steeped in water till the fluid acquired a brown tint nearly as deep as that of 
porter ; and he remained firmly of opinion, that pines, melons, and grapes, were 
much assisted by a copious use of this aliment. Being prepared from recent dung 
of the dovecote, he obtained at once a solution of the bile, the urea, and all the 
saline ingredients of the excreta. Gardeners in general may be presumed to have 
recourse, of necessity, to the brown drainage of old dunghills ; but here the result 
is a widely different affair, because the mass having undergone fermentation the 
gaseous and fluid products have been interchangeably attracted and re-formed into 
new chemical combinations : thus, the urea has developed ammonia during the 
first active stage of heat, the chief part of which passed into the air ; a portion 
however, as the mass cools, would sink into the lower parts of the heap or be 
carried down by rain, and become united with the black, carbonised substance 
which is termed humic acid, and gradually ooze through the bulk, forming that 
brown fluid which is seen in the waste drains and puddles of farm-yards. 
The chemical elements disturbed during the fermentation of a manure-heap 
are numerous : the oxygen and hydrogen combine to produce water ; other 
portions uniting with carbon yield acetic acid ; and certain saline and hydro- 
carbonaceous substances filtrate away ; leaving a cold, blackened mass, which 
constitutes the spit-dung of the gardener ; a substance composed chiefly of carbon 
and humus, in a condition fitted to evolve a considerable quantity of carbonic acid. 
The liquid drainage is then a weak compound of salts of potash, soda, and 
ammonia ; the last being united with so much of the humus as to give a deep 
brown tint to the whole. To appreciate the operation of this liquid, the chemical 
reader should test a variety of decayed vegetable matters ; such, for instance, as old 
leaf-mould, very black humous manure, and the brown peat of moors and bogs, 
by adding a little alkali to each of them. If an ounce of peat-bog or black 
manure be digested in boiling rain-water more than sufficient to cover the material, 
little colour will, in general, be extracted ; but upon adding, drop by drop, some 
strong caustic ammonia, stirring with a strip of glass after each addition, the fluid 
will gradually become of a deep full brown ; the pungent odour of the ammonia 
being destroyed till it be added to saturation. 
Again, a very little of the brown heath-soil from some parts of Surrey, being 
so treated, will give intense colour to an ounce or two of water. Pearl-ash and 
