These are all the varieties of cafes that can occur. When you fet about this kind of hunting, it is best to make all the openings you think neceffary at once; after that, by walking gently among them, you will catch them one by one, as they commence their operations.

Memoirs of the Society of Agriculture of Paris.

On the uses that may be made of Coutchouc, Elaftic Gum, or Indian Rubber, in Arts and Manufactures, with an account of the manner of obtaining and manufac

THE fubftance which forms the object of our present difquifition is called Coutchouc, by the natives of the country where it is fpontaneously produced. It is denominated elaftic gum, or elastic refin, by philofophers in Europe; but it is now generally known in the fhops by the name of Indian rubber; a substance that few of our readers are not acquainted with. It is a firm, tough, pliable fubftance, greatly refembling fome kinds of leather; but it poffeffes a degree of elasticity that cannot be equalled by any known fubftance in nature. It admits of being ftretched out in every direction to an astonishing degree; and when the diftending power is removed, it recovers its former shape and appearance. It neither can be diffolved in water, in ardent spirits, in acids, nor alkaline liquors, in the ordinary state of our atmosphere. Oils, in fome measure, act upon it; but the vitriolic æther is the only complete folvent of it that is as yet known. It is inflammable, and burns with a clear fteady flame, emitting then a flight smell, not at all difagreeable. When expofed to a cold air, it is more hard and rigid than under a milder temperature, but it neither becomes fluid, nor lofes its elasticity, till it be expofed to a much more

intenfe degree of heat than is ever experienced in any climate on the globe. It may, however, be melted by a very intenfe degree of heat; and then it affumes a thick vifcid appearance, like fome kinds of femi-fluid oils. And having once been reduced to that state, it cannot be again nade to acquire its former confiftence

or elasticity.

This substance is now well known to be the infpiffated juice of a tree. The natives in those regions where this tree abounds, extract the juice by making longitudinal incifions in the bark. It bleeds freely, and the juice, in a thick ftate of femi-fluidity, is collected into veffels placed to receive it at the bottom of the tree. It is then, by means of a brufh, fpread upon moulds prepared for the purpose, and fuffered to dry in the fun, or before a fire, which, by evaporating the moisture, foon brings it to the ftate in which it is fent over to us. By adding fucceffive layers above each other, it may be brought to any degree of thickness wanted; and by varying the form of the mould, it may be made to affume any shape or appearance you incline; which fhape, as has been said, it will ever afterwards retain, if no diftending force be applied to alter it.

From this fimple detail of facts, it is eafy to fee, that the uses to which this fubftance might be applied in arts and manufactures are innumerable, and fuch as can be effected by no other known substance in nature. Yet fo blind have mankind hitherto been to these advantages, that no attempts have been made in any acceffible region where extenfive manufactures could be established, either to cultivate the tree that produces it, or to induce the natives to fend the juice in its fluid ftate to Europe, where it could be properly manufactured. All that has been done is, to fuffer the natives to mould it into the form of a small kind of bottles, which is found to answer fome purpose among themselves; and thefe, when brought to Europe, are applied to fcarcely any other ufe than being cut to pieces for the

purpose of effacing marks made upon paper by a black lead pencil, or that of idly amufing children by ftretching it out, and obferving how perfectly it again recov. ers its priftine form, after having been diftended to a great length in any direction. We amufe ourselves with the phenomena without profiting by it, as children used to be amufed with the attraction of amber, before the phenomena of electricity were explained.

It is now time, that we should begin to make fome ufe of this very valuable fubstance, which, probably, a hundred years hence, will adminifter in a variety of ways to the accommodation of our defcendants. With that view, I shall here venture to point out a few of the ufeful purposes it may be made to answer; not doubting but the invention of men, whenever they can get the materials in their hands in abundance, will difcover a variety of other important purposes it will serve, that have not as yet been dreamt of.

For

ift. This fubftance fo much refembles leather, that it naturally occurs, that it might be employed for the purpose of making boots. Thefe would not only admit of being made of the neatest shape that could be imagined, but alfo, by being impervious to water, or the other corrofive liquors above named, would be fufficient to protect men from wet, though standing in water. feamen, fishermen and others, who are by their business obliged to wade in water, fuch boots would be of the greatest utility. The feet and legs might thus be protected from the action of even acids or alkaline subftances themfelves, wherever that fhould become neceffary.

ad. Gloves of this fubftance would be fo foft and pliable, as to allow the fingers perfect freedom of action, and in those kinds of bufineffes, that require artificers to put their hands among acids or corrofive liquors, they may become highly convenient.

3d. Caps. The ufes that might be made of this fubnce for defending the head from wet, are infinitely

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various, and might prove highly beneficial. A thin covering of this substance might be made for travelling hats, which, without adding any fenfible weight, would be perfectly impermeable by wet of any kind. Every other kind of covering for the head, might be thus rendered water tight, merely by giving them a flight coat of coutchouc, which would in no fenfible degree alter their other qualities. Bathing caps in particular, could thus be made extremely commodious, and at a fmall expence. This could be done, by covering with a coat of coutchouc an elaftic ftocking cap, which, merely by being pulled tight over the head, would embrace every part of it all round, fo as to prevent the entrance of water. The stocking and the covering being equally elaftic, they would contract and expand together without any fort of difficulty.

4th. Umbrellas.-Neck-pieces of filk, or other materials, cloaks or travelling coats of any sort, that should be judged proper, could thus be rendered perfectly water tight, without deftroying their pliability in the fmallest degree. It would only be neceffary to cover them with a coat of this foft varnish after they were made, fo as to close up the feams. Buckets too, all of canvas, or any other cheap fubftance, might be made water tight and incorruptible, by merely covering them with this matter. Veffels alfo for holding water and other liquors, that would not be liable to breakage, might thus be made of any fize or shape at a small expence. In short, it would take too much room to attempt to enumerate half the uses that might be made of it in the houshold way.

5th. In the army and navy, its ufes would be ftill more numerous and important. Tents are an article of very great expence: The canvas for them must be of the very best quality and clofeft texture; and after all, they are feldom proof against continued rain. At any rate, the viciffitudes of weather foon rot the canvas, and make a new supply in a short time be neceffary.

Were these tents covered with a coat of this fubftance, the entrance of rain through it would not only be altogether precluded, but alfo, the very wetting of the canvas itself would be prevented, and of courfe its durability be augmented to a tenfold degree. On the fame principle, the fails of a fhip would not only be made to hold the wind in the most complete manner, but by being covered by a thin coat of it on both fides, the failcloth itself could never be wetted, and of course, its durability be augmented, while its flexibility would not be diminished. Other ufes to which it could be applied in the army and navy, are fo numerous, as not to admit of being here fpecified. It is only neceflary barely to mention, that on a military expedition, to have a veffel capable of containing fluids, which, when empty, admits of being wrapped up like a handkerchief and put into the pocket, might on fome occafions be of inestimable value; and the fame at fea.

6th. Aeroftation is now nearly at a stand; but it is wonderful that no one ever perceived the ufe that might have been made of this fubftance for that purpose. No kind of filk, or other light fubftance could ever be found, that poffeffed the smallesft degree of elasticity; by confequence, when they afcended into the higher regions, the expanfion of the gas was in danger of bursting the globe; it was therefore neceffary to leave it open below to guard against that accident. A globe of coutchouc would have poffeffed the quality here wanted; it would have expanded as the circumftances of the cafe required; and while it was perfectly tight, to prevent the involuntary escape of the fmalleft quantity, it would have adapted itself in fize to every variation of circumstances. It is true, the retentive power of this fubftance, when very thin, has never yet been afcertained by experience; but there is reafon to believe it is very great.

7th. As this fubftance is inflamable, and burns with a bright flame without requiring any wick, it might be

VOL II.