Turbid water is cleared to some extent by placing a piece of common alum in it. A lump the size of a common nutmeg will be found sufficient to throw down a heavy sediment from a pailful of foul water. In India a species of nut or seed is made use of in the same way, and appears to act much in the same manner, although from different chemical affinities. In speaking of this water-clearing nut, the late Sir Emerson Tennent, in his admirable work on Ceylon, says: “To correct the impurity of the tank water when intended for their own use, the natives employ a horny seed (the production of a species of ‘strychnos’) about the size of a coffee bean, called by the Tamils ‘tettan kotta,’ and by the Singhalese ‘ingini’ (Strychnos potatorum). This they rub round the inside of the unglazed earthen chatty in which the muddy water is held till about one-half the seed is ground off, which, mingling with the water, forms with it a delicate mucilage. In the course of a few minutes the impure particles, being seized by this, descend, and, on their subsidence, form an apparently viscid sediment at the bottom, whilst the clear fluid remains at the top; and, although not altogether bright, is sufficiently pure for ordinary purposes. The curious and valuable plant S. potatorum, or the ‘clearing nut bush’ is abundant in the woods and mountains of the East Indies. It bears a shining fruit, which becomes black as it ripens. The trinal name is derived from the use which is made of the seeds, which, when dried, are sold by the native dealers in the bazaars expressly for the purpose of purifying turbid water.” This plant (Strychnos St. Ignatii, or St. Ignatius’s bean) is a climbing shrub without tendrils, bearing long drooping white flowers, which have the perfume of jasmine. The species is identical with the Ignatia amara of Linnæus. It is a native of Cochin-China and the Philippines, as well as of India proper.
Patent filter.
We, a short time since, invented and patented a small portable filter, which can be carried either in the breast pocket or holster. Its mode of use will be understood on reference to the [illustration]. Place the end of the tube (A) firmly in the pipe (B); fix the cover securely on the cup, and then thrust it with the hand beneath the surface of the foul water. Hold the mouthpiece (C) between the lips, and draw the air by sucking from the interior of the flask until the water flows freely into the mouth. If a draught of water is required for immediate use, the cover may be now removed, when the cup will be found full. If a larger quantity of water is needed, one or more flasks may be placed in an erect position in a tub or pail of water, set in action as before directed, and allowed to run until the water in the tub has reached the level of the flasks, which will not require holding under water when once filled by exhausting the air contained in them. To renew or cleanse the packing, which may consist of sponge, woollen cloth, flannel, wild cotton, or fine moss, unscrew the cover of the packing box within the cover, when it can be easily withdrawn and replaced. The tube, when not in use, is carried, coiled up, within the flask, which, on an emergency, may be made use of for boiling water, tea, soup, eggs, or meat. We have had the honour of exhibiting this simple but useful contrivance at meetings of the members of both the Royal United Service Institution and the Royal Society.
We have now applied the same principle to stoppers for bottles, or any other vessels, so that a common beer or sodawater bottle can be instantly converted into a syphon filter, as shown in the annexed illustration.
By the use of our invention we effectually get rid of the ova and larvæ of water insects, and the thousand and one living and dead impurities which are so abundant in the lakes, streams, and ponds of tropical countries. To get into the water contained in the flask or bottle, they would first have to pass through metal grating No. 1; then through the pores of closely-impacted sponge, woollen, or fine fibrous matter; and, lastly, through another grating, or strainer No. 2.
There is scarcely any possibility of foreign substances of any kind passing through the stuffing box, so that water, unless chemically tainted or poisoned by mineral solutions, can be rendered fit for use in two or three minutes by the use of either the metal flask or stopper.