Things being thus arranged, and every precaution to obtain accuracy observed, the charcoal in the furnace was lighted, and such a fire maintained in another furnace under the retort, as sufficed to keep the water therein contained, continually boiling, and thus to force the steam into the tube that passed through the burning charcoal.

"After the operation, we find," says Lavoisier, -" nothing but a few atoms of ashes remaining in the tube, the 28 grains of charcoal having entirely disappeared."

The products of the experiment were two gases, of a nature totally different from one another. The charcoal, situated as it was, that is-within the glass tube surrounded by fire, had decomposed the aqueous vapor which was conveyed through it; and uniting with one of the constituents of the vapor, passed into a receiver, and was found to consist of 144 cubical inches of carbonic acid gas, weighing 100 grains. This heavy gas had before been proved to be composed of carbon and oxygen; therefore, oxygen was found to be one of the constituents of water.

The other gas was observed to take fire, "when in contact with the air, by the approach of a lighted body;"-it occupied 380 cubical inches, but weighing only thirteen and seven-tenths grains. This was found to be hydrogen gas, and therefore, it was determined that water was composed of oxygen and hydrogen. The water expended in steam was eighty-five and seven-tenths grains: it had been proved by preceding experiments that, carbonic acid contained seventy-two grains of oxygen in every one hundred grains; therefore, as the carbonic acid gas produced (being one hundred grains), had taken seventy-two grains from the water, and as the hydrogen gas weighed thirteen and seven-tenths grains, the eighty-five and seventenths grains of water evaporated from the retort were accounted for, and the important chemical fact established that eighty-five and seven-tenths grains of water "are composed of seventy-two grains of oxygen, combined with thirteen and seven-tenths grains of a gas susceptible of combustion." This gas was subsequently named hydrogen gas, for the reason assigned in the introductory article, page 436, Vol. II. of the Horticultural Register. In the present state of widely diffused chemical knowledge, it will scarcely be needful for me to state that a variety of experiments by Lavoisier and his contemporaries, and by numberless chemists since his decease,wherein many different substances were made to act upon water, have proved, beyond a doubt, that the analyses of the fluid have invariably led to the same conclusion. It was also found that electricity excited by the common machine, was capable of separating the two

constituents; and the decomposition of water by voltaic or galvanic electricity forms one of the most beautiful and decisive proofs of its compound nature, and also of the general correctness of Lavoisier's deductions. If any doubt could by possibility have remained, it was removed by the converse of these experiments; that is, by the recombination of the constituents, and the reproduction of the fluid "element." I shall quote the substance of one of the most simple, and yet striking operations, the accuracy of which I can vouch, by the result of mine own experience.

Into a large crystal balloon, or globular glass, a certain given portion of carefully purified oxygen gas was admitted. A reservoir of the same purified gas was also at hand, from which the balloon might be re-supplied. This vessel was exhausted of its air, by an air pump, previously to the admission of the oxygen gas; and finally, by means of pressure, a small stream of hydrogen gas was made to pass into the balloon, which gas was immediately ignited by an electric spark. As the combustion proceeded, globules of water were deposited upon the inner surface of the globe, and these, enlarging into drops, ran down to the bottom of the vessel. I refer the reader to vol. I., page 144 of Lavoisier's Elements, for the particulars; suffice it to say that it required eighty-five parts by weight of oxygen, united to fifteen parts of hydrogen, to compose one hundred parts of water. "We exerted" says the philosopher-"on that occasion, the most scrupulous attention to accuracy; and have reason to believe that the above proportions cannot vary a two hundredth part from absolute truth."

The compound decomposable nature of water cannot be a question of doubt; the nature also, and proportion of its elements are understood, as far as our limited knowledge will authorise this assertion; but there are depths and mysteries in all these phænomena which are at present unfathomable and incomprehensible. How are the two gases held in union, and condensed into the form of liquid? By the abstraction, say the chemists, of their gaseous caloric which had previously kept them in a state of minute division! But can this be the fact? It is true that in the slow combustion of hydrogen, in an atmosphere of oxygen gas, a great volume of heat is developed; and in the case of the rapid combustion of a certain volume of the two gases blended together, a most violent explosion takes place. But then, light, as well as heat, is manifested, and what is light? How is that produced from two invisible, aëriform fluids, unless it previously exist therein.

I shall not here anticipate what I must refer to at large in a future paper. I shall only observe that, in order to produce light, heat,

and water, from the union of the two gases, the electric spark, or actual fire must be applied to them; otherwise, as I have seen, the gases may be blended in a vessel, and become wholly inactive and uninflammable, in a very short space of time.

The facts already ascertained lead to the following conclusions:

First. Water, by a variety of agencies can be decomposed; it can also be re-produced by the re-union and deflagration of the two actual products of the previous decomposition, and that, to a nice degree of accuracy in respect to quantities and calculation; of these facts there is no question or doubt whatsoever.

Second. As analysis and synthesis tend to establish the nature of water, the proofs deduced from the experiment are irrefragable and decisive: the theory is therefore legitimate and not to be impugned.

Third. Though we can trace effects, we are still lost as to causes. One point however, is pretty nearly confirmed, namely, the universality of the distribution of light, of that all-pervading body, fluid, or essence, which is the source of that manifestation which chemists style caloric. To it we must look for the solution of all those mighty phænomena which astonish the mind when it dwells upon the multiform transitions of water and its elements, when it reflects that, the bland, cooling fluid, which forms the basis of so many of our enjoyments, may be modified into steam, a floating vapour, rather lighter than air, or congealed into a solid mass of rock, hard as adamant, and equally capable of emitting flashes of etherial fire. Again, that this fluid, which, properly applied, will extinguish fire and flame, may, with the utmost facility, be converted into gases capable of producing combustion, the light of which, shall vie with that of the sun; while the heat shall surpass in intensity, any that the uninformed human mind could have the faintest conception of.*

I must now hasten to the consideration of the agency exerted by water in the processes of vegetable growth and developement. This must be most important, for it is impossible that a body so susceptible of decomposition, and whose elements are endowed with powers of such extraordinary energy, could remain torpid or inactive. But one experiment of analysis remains to be noticed, because it will tend to introduce the subject of the agency mutally exerted between plants and water, and also to prove that the decomposition of that fluid must be perpetually, and without intermission, proceeding during the progress of vegetable vital action.

Let a glass globe be filled with water, and a sprig or two of mint, or the green leaves of almost any tree, or a growing entire plant, be then introduced. The globe is next to be inverted, and placed in a vessel of water with its neck downward, so that no air may enter, nor water escape.

The plant or leaves are thus immersed; and in this situation, the vessel being exposed to the direct light of the sun, the foliage is acted upon by the rays of light passing through the media of glass and water. Bubbles of air are formed on the leaves, which increase in bulk, till they rise to the top of the globe, and displace some of the water. The gas thus developed, is found to be oxygen, for it supports combustion in a very eminent degree. Chemists say that the hydrogen of the water combines with the plant; they consider that it contributes to its nourishment; and that, in proportion as the hydrogen is taken up by the leaves, the oxygen gas is liberated.

The fact is decisive of the agency of light upon vegetables; but I am apt to doubt the accuracy of the deduction. I think it quite as probable that the water is taken up by the vegetable, and the decomposition effected within the cells, by the agency of the solar light, the gas set free, being propelled through the oscular pores of the leaves, as that the leaves merely attract the hydrogen, and thus cause the liberation of the other component. Be this as it may, the result is one of great interest; and it is connected with another, which will be noticed in a future paper, on the course of the vegetable fluids.

Every one knows that water is essential to the life and growth of plants; but a real mystery is involved in the consideration of the mode in which it acts upon them. Is water taken up in its simple, entire state, into the vegetable vessels; or is it decomposed in the soil, and assumed under the form of gas? Does it act simply as a solvent of the nutritive matters contained in the soil, thus enabling the processes of the roots to take up the essential qualities of those matters which otherwise could not find a passage through orifices of such infinite minuteness as those with which the rootlets are furnished?

These enquiries lead to the consideration of the following facts :Many plants will strike root very freely in water, whether that be pure from the clouds, or the more compound fluid from rivers and wells, which usually contains vegetable matter, and some chemical solution of chalk. These rooted plants will live for a considerable

time in the water, but do not appear to increase in any great degree; unless we except certain bulbous speces, which develope leaves and flowers in tolerable perfection.

Plants, or rather rooted cuttings, so formed, do not appear to take up much of the colouring matter of simple infusions. In fact, as I stated in a paper of the 7th Vol. of the Gardener's Magazine, young balsams, when dissected, gave no evidence of the presence of the colour from a strong infusion of logwood, in which they had been kept for many days; but these rooted cuttings have the marvellous property of preserving water from putridity for a very long period. It is known that flowers kept in water speedily cause it to become fetid, and full of animalcule. Now, I have by me at this instant, a portion of the water in which I struck a melon cutting, during the month of August. It remained clear, bright, and untainted, so long as the plant continued in it. I poured off a portion into a phial, about a mouth since, and it appears to be sweet and colourless to this day.

The energy exerted by the vital principle, is astonishing, and beyond the ken of mortal understanding. It appears to me that water is the pabulum of vegetable life, as perhaps, it was originally the source of all created matter; but that it undergoes some inexplicable change when in contact with the roots of plants, and blended with the soil. Probably it is decomposed by the nutritive matters in the soil, and becomes the simple sap of the plant, in consequence of this peculiar decomposition; during which process, as I have argued elsewhere, "electric agencies are develope!, which constitute the ascending current that propels and carries forward the prepared aliment, and deposits it in the vessels appropriated to the purposes of assimilation and distribution."

A plant in a pot will live and thrive in pure sandy-loam, when no manuring substance whatever is added to the soil, provided it be supplied with a sufficiency of water. It has been found that little or no waste of the substance of the soil has taken place during a very long period, but experience also proves, that plants, with very few exceptious, grow better when the soil has certain portions of vegetable matters in it. Now these matters remain comparatively inactive and unchanged, however frequently the soil be watered, provided no plant be growing among them; but if the roots of a living vegetable be there, the matters become changed, inore water is consumed, and the soil will require a renewal of the decomposable substances, or a change of the plant that it supports, in order to keep it in heart.

In concluding this article upon water, I conceive the conjecture