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diately ordered to be made, and in them the contents of a tub, which my servant usually committed to the com mon sewer, were carefully deposited: as washing suc ceeded washing, other pits were dug and filled; so that the whole garden, a small portion only excepted, has in this manner been watered and enriched: that small portion remains a visible demonstration of the uti lity of this manure. There vegetation is still languid; while the residue of the garden, invigorated by the suds only, annually exhibits a luxuriance almost equal to any thing this fertile neighbourhood can produce.

Remarks, by the Rev. T. FALCONER.

1. The above important experiment may perhaps remind the reader of the principal ingredients of the oil compost, suggested by Dr. Hunter of York. In the simple fluid manure we have an animal oil, potash, and water; in the compost are the same oil and the same alkali, but neither of them perhaps in so pure a state as in the manure, with the addition of "fresh horse-dung." The fresh horse-dung is added, in order to produce "heat and fermentation ;" and a delay of "six months" is supposed to be necessary, to make the compost "fit for use." All, however, that seems to be gained by the horse-dung is the animal oil, which may be united to the alkali during the process of fermentation, the straw, which in the fermentation of the compost will bind the mass together, and when decomposed on the ground, will afford a small supply of vegetable matter. If we make the comparison strictly accurate on the other side, we may observe, that in the fluid manure there must be an increased quantity of animal matter in the water, after it has been used for the purpose of washing linen.

The

The experiment then shews what is the advantage of the application of the oil and alkali only, as a manure ; and perhaps the delay of "six months" in preparing the compost would not be compensated by any superior efficacy that may be expected to arise from the combination of the horse-dung.

It also appears from the experiment, that the compost is a more useful discovery than Dr. Hunter himself could justly infer from his own limited experience of its effects.

2. This mixture of an oil and an alkali has been more generally known than adopted, as a remedy against the insects which infest wall fruit-trees. It will dislodge and destroy the insects, which have already formed their nests and bred among the leaves. When used in the early part of the year, it seems to prevent the insects from settling upon them; but whether by rendering the surface of the leaf disagreeable to the bodies of the ani mals, and thus repelling them, or by neutralizing the acid they deposit, and thus preventing the leaf from contracting into a necessary form for their reception, I cannot presume to determine. One of the modes by which this mixture indirectly contributes to the fertility of the ground, may be by its destruction of the insects which prey upon the plants.

It is also, I think, to be preferred to the lime-water, or the wood-ashes and lime, which Mr. Forsyth recommends to be used for the removal of insects. It is preferable to the lime-water and the lime, because lime loses its causticity, and with that its efficacy, by expo. sure to air, and must consequently be frequently applied; · and to the dredging the leaves with the fine dust of woodashes and lime, because the same effect is produced by VOL. XIII.-SECOND SERIES, R

the

the mixture without the same labour, and is obtained

without expense.

Mr. Speechley, in his treatise on the Vine, published in 1796, has used this mixture with great success; but he has applied it awkwardly and wastefully. He directs it to be poured from a ladder out of "a watering-pot over both trees and wall, beginning at the top of the wall, and bringing it on in courses from top to bottom." Page 161. Mr. Speechley is not the first person who has thought of this application of the mixture. It is a fact which has been long known and neglected.

A considerable extent of wall may be washed by means of a common garden-pump in a short time; and this operation should be repeated as often as a supply of the mixture can be procured; or if the water of a washing cannot be had, a quantity of potash of commerce dissolved in water may be substituted. The washing of the trees and wall twice a week for three or four weeks in the spring will be sufficient to secure them from the injuries of these insects.

On the whole, then, this must be considered as a valuable manure, as it can be obtained easily, at small expense, and in large quantities; and when its nature is well understood, will probably be no less esteemed by the farmer than horse-dung. To the gardener, as well as to the former, it is useful, mixed with mould, as a fertilizing compost; or when fluid may be applied to his fruit-walls, as a wash fatal to the noxious brood of predatory insects.

1

Mr. Speechley uses his mixture warm to soak the shreds, and wash the wall more effectually.

The

The Bakerian Lecture, on some new Phenomena of themical Changes produced by Electricity, particularly the Decomposition of the fixed Alkalies, and the Exhibition of the new Substances which constitute their Bases; and on the general Nature of alkaline Bodies.

By HUMPHRY DAVY, Esq. Sec. R. S. M. R. I. A.

From the TRANSACTIONS of the PHILOSOPHICAL SOCIETY of LONDON.

IN

I. Introduction.

N the Bakerian Lecture which I had the honour of presenting to the Royal Society last year, I described a number of decompositions and chemical changes produced in substances of known composition by electricity, and I ventured to conclude, from the general principles on which the phenomena were capable of being explained, that the new methods of investigation promised to lead to a more intimate knowledge than had hitherto been obtained, concerning the true elements of bodies.

This conjecture, then sanctioned only by strong analogies, I am now happy to be able to support by some conclusive facts. In the course of a laborious experimental application of the powers of electro-chemical analysis, to bodies which have appeared simple when examined by common chemical agents, or which at least have never been decomposed, it has been my good fortune to obtain new and singular results.

Such of the series of experiments as are in a tolerably mature state, and capable of being arranged in a connected order, I shall detail in the following sections; particularly those which demonstrate the decomposition and composition of the fixed alkalies, and the production

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of the new and extraordinary bodies which constitute.

their bases.

In speaking of novel methods of investigation, I shall not fear to be minute. When the common means of chemical research have been employed, I shall mention only results. A historical detail of the progress of the investigation, of all the difficulties that occurred, and of the manner in which they were overcome, and of all the manipulations employed, would far exceed the limits assigned to this Lecture. It is proper to state, however, that when general facts are mentioned, they are such only as have been deduced from processes carefully performed, and often repeated.

II. On the Methods used for the Decomposition of the fixed Alkalies.

The researches I had made on the decomposition of acids, and of alkaline and earthy neutral compounds, proved that the powers of electrical decomposition were proportional to the strength of the opposite electricities in the circuit, and to the conducting power and degree of concentration of the materials employed.

In the first attempts that I made on the decomposition of the fixed alkalies, I acted upon aqueous solutions of potash and soda, saturated at common temperatures, by the highest electrical power I could command, and which was produced by a combination of VOLTAIC batteries belonging to the Royal Institution, containing 24 plates of copper and zinc of 12 inches square, 100 plates of 6 inches, and 150 of 4 inches square, charged with solutions of alum and nitrous acid; but in these cases, though there was a high intensity of action, the water of the solutions alone was affected, and hydrogen and ox

ygen

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