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growing plants. The leaves which trees annually shed, and thesoft unripened shoots of a season, partake of the qualities of an-nual plants.
Herbaceous plants are such as spring from the ground, andarrive at maturity in the course of one season. Their existenceis either terminated by the course of nature, or they are' cutdown before the natural period of their existence arrives. A se-paration of the principles of which they are compounded is thenready to commence. The former, however, being more hardenedin the air, resist dissolution more than the latter. The processby which organized substances are decomposed and fitted againto enter into the composition of new plants, is called Fermenta-tion. This process has perhaps been less attended to than itsimportance demands: but as it is highly interesting in treatingof manures, and can be best traced in its operation on vegeta-bles, it may be proper here to take as distinct a view of die stepsby which it proceeds, as our imperfect knowledge will admit, toenable us to judge of the best mode of preparing the substancesdestined for manure.
Fermentation does not operate on frozen bodies, or when thetemperature is below the freezing point. After the natural juiceis evaporated, and vegetables become dry, they do not fermenttill they have imbibed water to moisten them : and though Four-croy found fermentable substances decompose in a vacuum, freeaccess to the air is acknowledged to be necessary to active fermen-tation. Thus, heat, water, and oxygen, are said to be the threeagents of fermentation. The sweet juices of ripe fruit or anyliquid vegetable extract, containing sugary matter, undergo threedistinct stages of fermentation ; the vinous, the acetous or hot,and the putrid. When the first commences, some oxj'gen is ab-sorbed from the surrounding air, sensible heat is diffused, carbon-ic acid gas is copiously formed and emitted, by which the carbonand oxygen of the subject is diminished, and the sugary matterconvened into spirit: In the next step of the process, oxygen iscopiously absorbed, the heat is considerably increased, hydrogenand carbon escape in carbonated hydrogen gas, the spirit is de-composed, and the acetous acid is formed. During the last orputrid stage, ammonia is formed, carbonic acid and carbonatedhydrogen gas escape, and the acid is decomposed ; gases stillcontinue to escape, till all the principles capable of assuming agaseous form are dissipated in air, and nothing remains but somerefractory carbon, a little earth and salts,
A short account of the process of fermentation on vegetablesubstances in a liquid state, to which philosophers have paidWost attention, is here given, to enable the reader to form someidea of the same process, as it operates on entire vegetables in asolid state, from the faint traces which follow ; this having beenE tlll less, attended to. As the substances destined for manure