ON MANURE. 
133 
iniediate attention being the application of liquid manure ; a practice which 
I ] pears to extend with great rapidity. In looking over the weekly publications 
I. horticulture, we cannot but be struck with the earnest recommendations of 
nd manures ; and as it is more than probable that they who look for correct 
formation in such publications, will attach faith to the advice they there meet 
ith, it becomes a duty to investigate the principles upon which this practice is 
unded. 
Mr. Knight, of Downton, was perhaps the first person of authority to whose 
Ivocacy we may ascribe the introduction of liquid manure : he employed pigeons'’ 
ing steeped in water till the fluid acquired a brown tint nearly as deep as that of 
)rter ; and he remained firmly of opinion, that pines, melons, and grapes, were 
uch assisted by a copious use of this aliment. Being prepared from recent dung 
( the dovecote, he obtained at once a solution of the bile, the urea, and all the 
line ingredients of the excreta. Gardeners in general may be presumed to have 
course, of necessity, to the brown drainage of old dunghills; but here the result 
I a widely different affair, because the mass having undergone fermentation the 
iiseous and fluid products have been interchangeably attracted and re-formed into 
)W chemical combinations : thus, the urea has developed ammonia during the 
L’st active stage of heat, the chief part of which passed into the air ; a portion 
jOwever, as the mass cools, would sink into the lower parts of the heap or be 
jirried down by rain, and become united with the black, carbonised substance 
Ihich is termed humic acid, and gradually ooze through the bulk, forming that 
frown fluid which is seen in the waste drains and puddles of farm-yards. 
II The chemical elements disturbed during the fermentation of a manure-heap 
re numerous : the oxygen and hydrogen combine to produce water ; other 
ortions uniting with carbon yield acetic acid ; and certain saline and hydro- 
irbonaceous substances filtrate away ; leaving a cold, blackened mass, which 
institutes the spit-dung of the gardener ; a substance composed chiefly of carbon 
nd humus, in a condition fitted to evolve a considerable quantity of carbonic acid. 
8 The liquid drainage is then a weak compound of salts of potash, soda, and 
fmmonia ; the last being united with so much of the humus as to give a deep 
rown tint to the whole. To appreciate the operation of this liquid, the chemical 
ieader should test a variety of decayed vegetable matters; such, for instance, as old 
|3af-mould, very black humous manure, and the brown peat of moors and bogs, 
y 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, 
ittle colour will, in general, be extracted ; but upon adding, drop by drop, some 
trong caustic ammonia^ stirring with a strip of glass after each addition, the fluid 
vill gradually become of a deep full brown ; the pungent odour of the ammonia 
•eing destroyed till it be added to saturation. 
Again, a very little of the brown heath-soil from some parts of Surrey, being 
0 treated, will give intense colour to an ounce or two of water. Pearl-ash and 
