No. X. 



On Manure. 



299 



Tlie liquid drainage is then a weak com- 

 pound of salts of potash, soda, and ammonia; 

 the last being united with so much of the 

 hiimus as to give a deep brown tint to the 

 whole. To appreciate the operation of this 

 liquid, the chemical reader should test a va- 

 riety 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- 

 Vi'ater more tlian sufficient to cover the ma- 

 terial, little colour will, in general, be ex- 

 tracted ; 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 odor of the ammonia being de- 

 stroyed 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 color to an ounce 

 or two of water. I'earl-ash and soda will 

 produce similar effects, but ammonia is to 

 be preferred. Persons are apt to conclude, 

 that to this brov/n coloring matter we must 

 ascribe the nutritive qualities of liquid ma- 

 nures: whereas, in fact, it is quite certain 

 that not one particle of the color can enter 

 the spongioid of sound, undislurbed roots. 



Now, if manure-water be weighed, and 

 then gradually evaporated at a gentle heat, 

 to dryness, the weight of coloring matter 

 will be found to be very trifling; and yet 

 gardeners are in the habit of adding much 

 water to this liquid, considering it too strong 

 for plants growing in pots. Having thus, 

 by dilution, reduced the tint to that of pale 

 malt liquor, what activity can be expected 

 from it] Or if such liquid manure be of 

 any avail at all, to what material can we 

 refer its nutritive effects, since it is admit- 

 ted that the particles of color, minute as 

 they must be, are still too gross to enter the 

 pores of the roots] 



To answer these queries by farther expe- 

 riment, and thus gain a littie more light 

 upon the subject, — let a few grains of pow- 

 dered quicklime be stirred into the colored 

 fluid and suffered to subside; after a few 

 minutes it will be seen that the color of the 

 liquid is lost; that it has become quite pale; 

 while the sediment itself has acquired a 

 dingy brown tinge and a flocculent texture. 

 As a converse of this experiment, let brown 

 peat or black manure be worked up with 

 one-third the quantity of quicklime, and di- 

 luted with hot water sufficient to allow of 

 free subsidence. After stirring from time 

 to time, the compound matter will subside, 

 leaving the super-natant liquor nearly de- 



void of color : — and now caustic ammonia 

 may be added to excess, witliout effecting 

 any change of tint, the lime acting by more 

 powerful affinity, and fixing tlic humic ex- 

 tractive in the tbrm of an insoluble humate 

 of lime. 



In this way it is that lime acts as the spe- 

 cific reclaimer of waste and barren peat- 

 bogs, renriering them fertile by the ahslrac' 

 tion and fixation of that inert and deleteri- 

 ous vegetable matter which is an antagonist 

 to vegetation. And thus, by an induction 

 from undeniable cliemical facts, we begin to 

 perceive that we have long been misled by 

 crude theories and empirical practice. 



Liquid 7nanures therefore act by the salts 

 which they contain, not by the coloring so- 

 lution of humus; and thus, also, we may be 

 permitted to sanction the cautious applica- 

 tion of artificially prepared fluids, as for in- 

 stance " Potter's Liquid Guano," " Hum- 

 phreys' Inodorous Compound," and other 

 fertilizers, which are neither more nor less 

 than solutions of chemical salts; among the 

 safest and most effectual of which are the 

 sulphate of ammonia, nitrate of potassa 

 (salt-petre,) and sulphate of soda. 



Lime is the interpreter of this new and 

 most intelligible theory; for by it the im- 

 portant fact has been ascertained, that, for 

 all the poisonous vegetable extract in peat- 

 bogs, in old pastures, in gardens and soils 

 over-glutted with manure, it exerts the most 

 powerful affinity, attracting the humic acid, 

 not only from alkaline solutions, but from 

 the body of the soil itself, fixing it in a con- 

 dition of absolute insolubility, and thereby 

 rendering the poison quite innocuous. 



Let us not be misunderstood, however ; 

 for when pure turfy loam without dry ma- 

 nure is used in pot-culture, the slight tinge 

 of color in the liquid superadded cannot be 

 productive of injury. What we wish to 

 combat, is the false notion, that the coloring 

 matter is the manure. 'The truth must pre- 

 vail, in proportion as science and faithful 

 analysis extend their influence ; yet, while 

 we assert that the chemical salts of steeped 

 manures are the fertilizers, and that if the 

 coloring matter of drainage from the mixen 

 were perfectly discharged by lime not used 

 in excess, the clear fluid would retain its 

 efficiency, we still give the preference to 

 tliese agents, the products of natural fer- 

 mentation, over any salts prepared by art in 

 the laboratory. 



As an analogy, we would cite the well- 

 authenticated facts of the rapid germination 

 of seeds which have passed through the 

 viscera of birds. The Pimento trees which 

 furnish the allspice of commerce, are quickly 

 raised by berries, thus impregnated by animal 



