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A sinall pith-ball, suspended I believe with a single thread of a silkworm, vibrated between two fixed pith-balls, one of which was connected with the apparatus, the other communicated with the table.
23rd Oct. A coated jar had a slight charge given to it with one of the electric rods. When the zinc pole charged the inside of the jar, that side gave signs of a minus state (as it is called), and the outside a plus state. This was shown by an electrometer, the leaves of which diverged when excited amber was holden near it, after it had received electricity from the inside, and converged when electrified from the outside of the bottle. From the usual effects of galvanism the contrary might have been expected; that is, that the zinc end of the column would have produced the plus state, and the silver end the minus
24th Oct. With three rods combined, a small brass ball suspended by silk between two bells vibrated between them, causing them to ring: the bells were suspended from the ends of the apparatus. The next day, 25th Oct. (the jubilee day), having fixed on glass pillars two bells, and hung by silk a brass ball from the upper part of a piece of wire, I placed the bells in connexion with the ends of the combined apparatus, by means of bent wires laid on them : the apparatus and bells were left for near an hour, during which time the bells kept ringing, at times stopping for a short interval, then ringing again; the clapper sometimes was seen to rest against one of them, then appeared to be disengaged by a person moving in the room. Whether the disengagement was always owing to some slight shaking of the table, or whether it was sometimes in consequence of the ball having acquired electricity, and then being repelled, I am not quite clear. It appears not improbable but that the weight of the clapper may be so adapted to the power of the apparatus, as to cause small bells to continue ringing for several years without intermission; if so, we shall have a machine which, by those who do not consider the subject philosophically, will be called a perpetual motion. How long the column will continue to produce the electric fluid cannot at present (or perhaps ever) be determined. The principal difficulty to be overcome, in order to keep the clapper in continual motion throughout the different seasons of the year, appears to be the want of a very accurate insulation of the apparatus ; for, if the glass tubes or pillars which support them are damp, the current of the electric fluid will not pass along in the proper direction for the experiment.
29th Nov. Five rods, each of five bundred series, were combined; with these, two small bells kept ringing on and off for more than four hours, part of which tinie I was not in the room, so cannot tell how often they might have stopped: the ringing sometimes began again evidently not from any shake, but I imagine from the clapper having become electrified, and then being (as it is usually called) repelled from the bell against which it rested. I placed three rods of five hundred series (insulated), in a box, and brought wires from the ends of this combined apparatus, which I made communicate
with two bells. I placed, on Tuesday, 27th February, 1810, this apparatus in a closet, where I left it until Sunday, 11th March, the bells continuing to ring (as far as my observations went), from the time they were put into the closet until that day; when they ceased. What was the cause of their stopping I do not know, but imagine it was owing to dampness. I cannot ascertain that they rang the whole time without stopping, but have no reason to believe otherwise, I intended some months ago to have sent you the description of the above-mentioned apparatus with experiments, but deferred sending it on account of Mr. De Luc's paper not being published, which he sent to the Royal Society, in March, last year, and which contains a description of the electric colunin and its properties. He hopes soon to publish it himself. In the mean time he has permitted me to communicate my account to you. I consider the invention of this column as the most important discovery in the science of electricity since that of the voltaic pile, and do not doubt but that when Mr. De Luc gives his paper to the public, it will prove extremely interesting, and I have reason to believe it may lead to further discoveries which will be considered as very important in this branch of science.
On Wednesday night, 14th March, I put into a closet a couple of bells, communicating with the three rods above mentioned in a box ; they then began to ring, and are now ringing :-how long they will continue so I cannot say, perhaps some change in the weather may soon occasion the clapper to cease vibrating.
I remain, &c.,
B. M. FORSTER. Walthamstow, Essex, 20th March, 1810.
On the Chemical Statics of Organized Beings. By M. Dumas.*
(Continued from page 293). III. Let a seed be thrown into the earth, and be left to germinate and develope itself; let the new plant be watched until it has borne flowers and seeds in its turn, and we shall see, by suitable analyses, that the primitive seed, in producing the new being, has fixed carbon, hydrogen, oxygen, azote, and ashes.
Carbon.—The carbon originates essentially in carbonic acid, whether it be borrowed from the carbonic acid of the air, or proceed from that other portion of carbonic acid which the spontaneous decomposition of manures continually gives out in contact with the roots.
But it is from the air especially that plants most frequently derive their carbon. How could it be otherwise, when we see the enormous quantity of carbon which aged trees, for example, have appropriated to themselves, and yet the very limited space within which their
• “ London and Edinburgh Philosophical Magazine.”
roots can extend ? Certainly, when a hundred years ago the acorn germinated which has produced the oak that we now admire, the soil on which it fell did not contain the millionth part of the carbon that the oak itself now contains. It is the carbonic acid of the air which has supplied the rest, that is to say, nearly the whole.
But what can be clearer and more conclusive than the experiment of M. Boussingault, in which peas, sown in sand, watered with distilled water, and having no aliment but air, have found in that air all the carbon necessary for development, flowering, and fructification ?
All plants fix carbon, all borrow it from carbonic acid; whether this be taken directly from the air by the leaves, whether the roots imbibe within the ground the rain water impregnated with carbonic acid, or whether the manures, whilst decomposing in the soil, supply carbonic acid, which the roots also take possession of to transmit it to the leaves.
All these results may be proved without difficulty. M. Boussingault observed that vine leaves which were enclosed in a globe took all the carbonic acid from the air directed across the vessel, however rapid the current. M. Boucherie also observed enormous quantities of carbonic acid escape from the divided trunk of trees in full sap, evidently drawn by the roots from the soil.
But if the roots imbibe this carbonic acid within the earth, if this passes into the stalk and thence into the leaves, it ends by being exhaled into the atmosphere, without alteration, when no new force intervenes.
Such is the case with plants vegetating in the shade or at night. The carbonic acid of the earth filters through their tissues, and diffuses itself into the air. We say that plants produce carbonic acid during the night: we should say, in such a case, that plants transmit the carbonic acid borrowed from the soil.
But let this carbonic acid, proceeding from the soil, or taken from the atmosphere, come into contact with the leaves or the green parts, and let the solar light, moreover, intervene, then the scene all at once changes.
The carbonic acid disappears; bubbles of free oxygen arise on all the parts of the leaf, and the carbon fixes itself in the tissues of the plant.
It is a circumstance well worthy of interest, that these green parts of plants, the only ones which up to this time manifest this admirable phenomena of the decomposition of carbonic acid, are also endowed with another property not less peculiar, or less mysterious.
In fact, if their image were to be transferred into the apparatus of M. Daguerre, these green parts are not found to be reproduced there ; as if all the chemical rays, essential to the Daguerrian phenomena, had disappeared in the leaf, absorbed and retained by it.
The chemical rays of light disappear, therefore, entirely in the green parts of plants ; an extraordinary absorption, doubtless, but which explains, without difficulty, the enormous expense of chemical force necessary for the decomposition of a body so stable as carbonic acid.
What, moreover, is the fixed function of this carbon in the plant ? for what is it destined ? For the greater part, without doubt, it combines with water or with its elements, thus giving birth to matters of the highest importance for the vegetable.
If twelve molecules of carbonic acid are decomposed and abandon their oxygen, the result will be twelve molecules of carbon ; which, with ten molecules of water, may constitute either the cellular tissue of plants, or their ligneous tissue, or the starch and the dextrine which are produced from them.
Thus, in any plant whatever, nearly the entire mass of the structure (charpente), formed as it is of cellular tissue, of ligneous tissue, of starch, or of gummy matters, will be represented by twelve molecules of carbon united to ten molecules of water.
The ligneous part which is insoluble in water, the starch, which gelatinizes (l'amidon, qui fait empois) in boiling water, and the dextrine which dissolves so easily in water cold or hot, constitute, therefore, as M. Payen has so well proved, three bodies possessing exactly the same composition, but diversified by a different molecular arrangement.
Thus, with the same elements, in the same proportions, vegetable nature produces the insoluble walls of the cells of cellular tissue and of the vessels, or the starch which she accumulates as nourishment around buds and embryos, or the soluble dextrine which the sap can convey from one place to another for the wants of the plant.
How admirable is this fecundity, which out of the same body can make three different ones, and which allows of their being changed one into the other with the slightest expense of force every time occasion requires it!
It is also by means of carbon, united with water, that the saccharine matters so frequently deposited in the organs of plants for peculiar purposes, which we shall shortly mention, are produced. Twelve molecules of carbon and eleven molecules of water form the cane sugar. Twelve molecules of carbon and fifteen molecules of water make the sugar of the grape.
These ligneous, amylaceous, gummy, and saccharine matters, which carbon, taken in its nascent state, can produce by uniting with water, play so large a part in the life of plants, that, when they are taken into consideration, it is no longer difficult to understand the important part that the decomposition of carbonic acid performs in plants.
Hydrogen.-In the same manner that plants decompose carbonic acid for the appropriation of its carbon, and in order to form together with it all the neutral bodies which compose nearly their entire mass, in the same way, and for certain products which they form in less abundance, plants decompose water and fix its hydrogen. This appears clearly from M. Boussingault's experiments on the vegetation of peas in closed vessels. It is still more evident from the production of fat or volatile oils so frequent in certain parts of plants, and always so rich in hydrogen. This can only come from water, for the plant receives no other hydrogenated product than the water itself.
These hydrogenated bodies, to which the fixation of the hydrogen borrowed from the water gives birth, are employed by plants for accessory uses. They form, indeed, the volatile oils which serve for defence against the ravages of insects ; fat oils or fats, which surround the seed, and which serve to develope heat by oxidation (en se brûlent) at the moment of germination ; waxes with which leaves and fruits are covered so as to become impermeable to water.
But all these uses constitute some accidents only in the life of plants ; thus the hydrogenated products are much less necessary, much less common in the vegetable kingdom, than the neutral products formed of carbon and water.
Azote.-During its life every plant fixes azote, whether it borrows the azote from the atmosphere or takes it from the manure. In either case it is probable that the azote enters the plant, and acts its part there, only under the form of ammonia or of nitric acid.
M. Boussingault's experiments have proved that certain plants, such as Jerusalem artichokes, borrow a great quantity of azote from the air: that others, such as wheat, are, on the contrary, obliged to derive all theirs from manure : a valuable distinction for agriculture ; for it is evident that all cultivation should begin by producing vegetables which assimilate azote from air, to rear by their aid the cattle which will furnish manure, and employ this latter for the cultivation of certain plants which can take azote from the manures only.
One of the most interesting problems of agriculture consists, then, in the art of procuring azote at a cheap rate. As for carbon, no trouble need be taken about it; nature has provided for it; the air and rain water suffice for it; but the azote of the air, that which the water dissolves and brings with it, the ammoniacal salts which rain water itself contains, are not always sufficient. With regard to most plants the cultivation of which is important, their roots should also be surrounded with azotated manure, a permanent source of ammonia or of nitric acid, which the plant appropriates as they are produced. This, as we know, is one of the great expenses of agriculture, one of its great obstacles, for it possesses only the manure which is of its own production. But chemistry is so far advanced in this respect, that the problem of the production of a purely chemical azotated manure cannot be long in being resolved.
M. Schattenman, the skilful director of the manufactories of Bouxvilliers in Alsace, M. Boussingault, and M. Liebig have turned their attention to the functions of ammonia in azotated manures. Recent trials show that the nitric acid of the nitrates also merit particular attention.