He answered, that he had seen some of the juice at the Royal Institution, where it had been brought from Mexico to be analysed; but that, in general, caoutchouc was imported in a solid state. “A cheap method,” he continued, “of dissolving it was discovered by Mr. Mackintosh; and his mode of applying it to cloth, linen, silk, or any materials of that kind, was equally ingenious and useful. When reduced to a fluid state, a sufficient coat of it is laid upon the cloth, and another piece being then spread over it and pressed together, they become permanently united as well as water-proof; but as the outside and the inside need not be similar, you may have the one of cloth, and the other of velvet; or a camlet cloak lined with silk, or any other combination you please.
“There are many other purposes to which this contrivance has been applied. Hoses for conveying the water from fire-engines, when made of canvas and caoutchouc, and without seam, are much stronger, more durable, and more flexible than those made of leather. I have been told by a naval officer that a hose of this sort affords an excellent mode of filling the casks in a boat, from a well or stream near the shore, when a heavy surf prevents their being landed; for it is obvious that such a hose may pass through the sea, without the possibility of the fresh water it conducts being tainted by the salt. It is also well adapted to tilts for waggons and hayricks; it would make admirable military tents; and you may imagine what a comfort water-proof bags must have been in Captain Franklin’s expedition to the Polar Sea, in keeping the men’s clothes dry, notwithstanding the dismal weather to which they were so often exposed.
“There is only one more use which I will now mention. Any substance that is carefully coated with this gum is as impervious to air as to water: bags therefore made in the shape of cushions or pillows, which can be folded up and carried in the pocket, may be in a few moments inflated with the breath, by means of a small pipe; and even beds, which when empty would occupy but little room in a portmanteau, would often preserve the health, and greatly add to the comfort of travellers in certain countries, where a dry, clean, and soft bed is an unattainable luxury.”
Miss Perceval told us that in some of the forests of Guiana, a substance, called dapicho by the Indians, is found in large masses under ground; and which, having all the properties of the recent gum, was long known by the name of fossil caoutchouc. But the indefatigable Humboldt, having at last succeeded in finding some of it undisturbed in the ground, at once perceived that it had oozed out of the roots of caoutchouc trees which were so old that the interior had begun to decay. It is white and brittle, till exposed to a strong heat; and when sufficiently beaten with a heavy club it acquires great elasticity. The Indians make their famous tennis balls of it; it is also cut into corks, which are very superior to those made of the cork tree; and it is worked up into enormous drum-sticks—the drum being merely a hollow cylinder of wood about two feet long.
“There is, however,” my uncle observed, “a species of fossil caoutchouc. It is, in fact, a bitumen, but flexible and elastic; and, as it has the property of cleaning off pencil-marks in the same manner as Indian rubber, it has been named mineral caoutchouc.”
I asked him if it might not be some of the dapicho, which had lain buried in the ground, long since the trees, from which it oozed, had perished?
“I have but two reasons, Bertha, to oppose to your theory. It is only found near Castletown in Derbyshire, and you know the English climate is not very well suited to those trees—and secondly, it is in the deep recesses of a lead mine, surrounded by spar and limestone.”
June 1st.—You may remember, mamma, how much I was interested, last year, by my uncle’s illustrations of the Mirage and the Fata Morgana. The subject was often afterwards alluded to in conversation; and my aunt having incidentally mentioned it to her charming correspondent in Upper Canada, I was this afternoon agreeably surprised by her reading aloud the following passage in a letter which she had just opened:—
“Your young friend Bertha will be pleased to hear that last June I witnessed something very like that curious phenomenon which you say interested her so much. One morning I awoke just at the break of day, and accidentally directing my eyes to the window, which has a southern aspect, I was astonished to see—instead of the black monotonous forest by which we are surrounded—a wide, magnificent sheet of water, connected with a spacious river winding to a great distance, and confined by gentle slopes and grassy banks; and all this so distinct that the bright fresh green of the young leaves was beautifully contrasted with the dark foliage of the pine woods.
“I rubbed my eyes, and looked again—for it appeared to be exactly our lake near Peterborough, with the Otanabee River winding towards Rice Lake, except that the whole view was reversed. I wondered how all this could be seen over our lofty trees, and I went to the window and leaned out to look for objects which I knew—but nothing was to be seen except my beautiful and inexplicable landscape. I lay down—and still saw it from my pillow;—but my eyes gradually closed—and, when I again wakened, heavy mists had risen with the sun—and my fairy prospect had vanished.