LIQUID MANURES CHEMICALLY APPLIED 
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comparison with the well-defined proportional alliances of ordinary chemical com- 
pounds. But independently of purely organic structure, plants endowed with life 
introsuscept a great number and variety of purely chemical, inorganic salts, and 
those chiefly from the soil. 
The earths proper — of metallic origin— are also to a certain extent absorbed and 
deposited in certain specific conditions, varying according to the peculiar tempera- 
ment of the vegetable subject. 
If, then, any liquid manure is found to produce a marked effect upon a plant, 
that effect must depend chiefly, if not entirely, upon the salts which it holds in a 
state of aqueous solution ; therefore, in order to understand the mode in which any 
given solution can act, we must submit it to correct analytic experiment. Let us 
take for the type that compound fluid which results from a portion of the best and 
purest Bolivian guano ; for there we detect nearly all the elements which are 
traceable in the saline product of organised vegetable life. The soluble salts of 
such guano are sulphates of potass, of soda, and of ammonia ; muriate or chlorides of 
soda and ammonia ; phosphates of ammonia, &c. ; and also a quantity of free urea. 
We do not pretend to determine the proportions or exact quantities of those salts, 
the variableness of guano being proverbial ; but that they all, or most of them, are 
present, in certain proportions, may be considered an admitted general fact. The in- 
soluble components of good guano consist chiefly of the bone phosphate from fish, 
reduced to a state of division so minute as to defy comparison — of urate of ammonia 
— of ammonio -phosphate of magnesia — and of some other minor ingredients, 
among which we have detected an oxide of iron, and a quantity of organic matter, 
that represents, as nearly as may be, the compound which of late has been termed 
humus, since it is destructive by fire, excepting that small portion of siliceous sand 
which most samples of guano are found to contain. 
If, then, guano be employed as liquid manure, it is plain that every plant must 
be injured, unless it be constitutionally inclined to imbibe and receive nutriment from 
the salts contained ; and even then the solution should be exceedingly weak, and be 
used with discretion. 
Potter's guano appears to combine sulphate of ammonia as its chief active in- 
gredient, common salt in smaller proportion, a quantity of powdered chalk (these 
two susceptible of mutual attraction), a little vegetable alkali, and much bone-dust. 
It is not guano, but a very useful dress for the farm, — and the liquid will contain the 
salts named, with the addition of some free ammonia, owing to the action of the 
potash upon the sulphate. 
If steeped manures — as sheep-dung, horse-droppings, cow's, deer's, or pigeon's - 
dungs — be used, in a state of fermentation, a peculiar saline matter may be present, 
which, in all probability, will be most correctly called humate of ammonia, a 
compound that claims the strictest attention, and which we shall now attempt to 
describe. 
This salt of ammonia is produced by the attraction or chemical affinity which 
