ing, between its interstices or pores, the solid matters contained in suspensio in the water.

Mild and strong clays were found by Dr Hassall to possess remarkab purifying properties. Urine passed through a filter of clay was found clear and free from smell as the purest water. The researches of Profess Way, chemist of the Royal Agricultural Society of England, have been strumental in proving that "clays and loams have powers of chemical acti for the removal of organic and inorganic matters from water to an exta never before suspected." As a representative of pure natural clay, the P fessor used what is called "plastic clay" for his experiments-better kno as "pipeclay."

Filters are not only exceedingly useful for purifying water from organ impurities, but also, as we have seen, from various chemical gases and so tions. Their use in freeing water containing lead is remarkable. Thus very simple practical means for separating lead wherever it contamina water was discovered.

Having now noticed the process of filtration as briefly as the importa nature of the subject has admitted, we proceed to the description of vario kinds of filters for use.

In fig. 54 we give a sketch of a simple filtering cistern, adapted for r water, or where an intermittent supply is derived from a pump.

narrow division at one end of t large cisteru, made by a partiti a b, as in the dra ing. This partit

must not qu reach the botto

but a space bel through which t water can pass from the large division to the small one. The water to filtered is admitted to the large division first, and passes through aperture above noted, up through the filtering medium g and into e e, fr whence it is withdrawn through the pipe f. As the water is drawn fr e e, that in a a, from its tendency to find its level, will pass through: aperture b, and up through g as before. The filtering medium may be ranged as follows: First, in the bottom place a layer of clean round pebbl

Fig. 55.

b

and pieces of broken earthenware; above th small clean gravel, then coarsely pound charcoal, a second layer of gravel, and last clean sharp sand. A good filtering media may be made by placing a layer of gravel bottom; above this a layer of coarse wool, the a layer of finer wool, and above these one gravel. In place of having the position of filtering medium as in the last, it may be si ated in a box b b, fig. 55, with a perfora bottom cc, the water being admitted to through the pipe d; passing through the fil ing medium, it will be delivered to the body of the cistern, from which

α

a

Fig. 56.

d

α

may be drawn free from impurities in the usual way. If a portable filter 3 required for spring, burn, or rain water, one made as in fig. 56 will be effective. A water-tight box, a a, should have a stop-cock, b, to withdraw its contents at the bottom; it should be supported by legs, c c, sufficiently long to raise the box so as to allow a vessel to be placed underneath the stop-cock b, to receive the filtered water. Provide a zinc box, d d, or one made of wood, lined with gutta percha, similar to that in fig. 57. This box should have a perforated bottom, and a bead, bb, at the upper edge, or other contrivance so as to prevent it from going into the box a a farther than requisite; the box may have handles, c c, to lift it out and in. The filtering edium should be arranged in the bottom of this box as in the sketch; the

Fig. 57.

с

water admitted to it passes through the filter and into the part e e of the outer box; nearly the whole of the box a a may be made available water-space by placing the bead or ledge of the filtering-box near the bottom, which will keep it farther up in the box a a. By adopting the plan sketched in fig. 58, a still more simple and inexpensive water-filter may be made. A large flower-pot, a a, is provided ith a plug c, or stop-cock, by which the filtered water may be drawn off;

Fig. 58.

J

a

a circular frame of wood, d d, of a little larger diameter than the diameter of the pot a a, should lie on the top ledge. This frame has a hole or aperture in the centre, of size sufficient to allow a smaller flower-pot, e e, to pass down into the interior of the large one, yet to hang by its ledge or rim, as in the drawing. The whole apparatus is supported on legs, b b. The filtering medium is placed in the small pot, and the water passes through this from ƒ, and is delivered to the interior of the large pot, from whence it is withdrawn by the plug or stop-cock c.

The Reverend Mr W. Law, of Marston Rectory, Welford, has designed a filter for domestic use,

b which is very simple in its construction, and, we believe, most effective—the filtering media being arranged that their interstices are not liable to be clogged up. For the accompanying diagrams and description, we are indebted to the ges of the Domestic Economist.

"A chimney-pot made of burnt clay, and procurable at almost any brickrd, free from flaws, and waterproof at the sides, is provided with five or angular openings, about 5 or 6 inches broad, at the base, as in the sketch .59.

A circular piece of oak board an inch thick, with a central opening suffintly large to admit of its being fitted close to the outside of the chimneyt, is placed at the distance of 6 inches from its base. This board is

C

Fig. 59.

1

pierced with a number of holes, and should have a projecting width of inches. The chimney-pot and its appendag stand in a cylindrical tub, or barrel, the interna diameter of which corresponds with the circul oak-board. A white metal tap is fixed into th barrel, about 10 or 12 inches above the perforat board. The filtering medium which rests up the circular wooden strainer is composed, fir of a 2-inch layer of fine well-washed grave upon this is placed a 4-inch layer of coarsel pounded charcoal, then from 3 to 6 inches well-washed river sand (the thickness of which stratum must depend upon its coarseness). The filter would now be complete, were it not fu the tendency of the water, with which the inner cylinder is filled, to displace, by the force of it ascent (always proportionate to the height of the water in the inner cylinder), the last stratum To obviate this, I lay upon the sand a piece coarse linen cloth of double thickness, and upon this a 2-inch stratum gravel, similar to the first layer. The height of the chimney-pot I use i about 5 feet; but there are various sizes. I conceive a cylindrical vesse made of good Roman cement, would answer the purpose equally well The operation of this filter is too manifest to require further description." We have now to take into consideration the next department unde this head-namely, the "Softening of Hard Water." In many districts the only supplies of water available are what are termed hard. We have alread shown how important it is, so far as regards health and economy, to hav soft water for domestic purposes. A knowledge, then, of the method rendering hard water soft is desirable, where these requisites are considere worth attending to.

The hardness of water is generally tested or recognised by the difficult there is in making a soap-lather with its aid. In the great majority of case the hardness of water is caused by the presence of chalk in solution. D Clark has patented a method of freeing water from this impurity by method as simple as it is efficacious. It is now the universally received method of softening hard waters.

As this process is patented for Great Britain, it cannot be carried out on a large scale for public purposes without incurring the risk of a prosecution for "infringement;" but it can be imitated in the colonies on a small scale for family use, by using lime water. About a gallon of strong lime wate may be kept in a well stoppered bottle, to be used when required: this quantity will soften a large amount of water. The following are the ad vantages claimed by Dr Clark, which will on trial be fully borne out:

"1st, The water will be much softened, and to such a degree that, in lies of from 24 to 32 ounces of the best curd soap being required to form a com plete lather, with 100 gallons of the water supplied by the London Com panies, a similar lather may be produced by about one-third of the soap with 100 gallons of the same water purified by the trial process. 2d, The new process will prevent fur in boiling. 3d, It will separate vegetating and colouring matter. 4th, It will destroy insects. 5th, It is remarkable

a chemical process for merely withdrawing matter from solution in water parting none.”

The following is the method recommended by Mr Holland for using the ne water: Two jugs are to be provided, one holding thirteen times as much the other. Fill the smaller one with a saturated solution of quick-lime me water); put this quantity into the larger one, and fill it up with the ater to be purified, and mix the two together. The chalk is slowly desited, and the clear water filtered for use.

CISTERNS.

In fig. 53 we have given a plan suggestive of a method of constructing a stern, forming part of the outhouse, and in fig. 54 another sketch of a tering cistern. We now offer an arrangement recommended by Mr ephens in the Book of the Farm, to which we are indebted for the descripon and illustration.

"Let a b c b, fig. 60, be a cistern of stone or wood, placed at a convenient ot of the steading or farm-house, for the reception of rain water. I have

Fig. 60.

k

•

n

g

C

m

found that such a cistern, of the capacity of 12 cubic feet, holds a sufficient quantity of rain water for the domestic purposes of an ordinary family. A cistern of 2 feet square at the base, and 3 feet in height, will just contain that quantity; but, as the size of an ordinary wash-tub is 2 feet in diameter, the space between d and d must be made 2 feet 6 inches at least, and the height of the cistern b would be 2 feet; but if more water is required than 12 cubic feet, then the height should be 3 feet, which gives a capacity to the cistern of 18 cubic feet. Suppose the cistern represented in the figure to contain 18 cubic feet, then the area of a will be 2 feet square, and 3 feet in height, supported on two upright stones, d d, of the breadth of the cistern, and 2 feet high. The cistern may either be made of a block of freestone hewn out to the dimensions, or of flags, of which the sides are let into grooves in the bottom and into each other, and imbedded in white lead, and fastened together with iron clamps, having a ne movable cover c; or it may be formed of a box of wood, securely tened at the corners to be water-tight, with a cover of wood, and resting the stone supports d d. Stone, being more durable, is, of course, preable to wood for a cistern that stands out in the open air. A hollow per cylinder g is fastened perpendicularly into the bottom a, having its

d

p

lower end projecting 1 inch below, and its upper 3 inches above, the respectiv surfaces of the bottom. The upper end of the copper cylinder is formed to r ceive a ground truncated cone of copper h, called a plug or stopper, which moved up and down with a lever k, by means of the copper rod i. The p h must be made water-tight with grease, the rod of which passes through hole in the cover, to be connected with the lever k, whose support or f crum is fixed on the cover. These parts are all made of copper, to wit stand rusting from the water, with the exception of the lever, which ma be of iron, painted. The rain water is supplied to the cistern by the pi e, which descends from the rain-water conductor, and is let through a he in the cover. The water is represented standing as high as 7; but in a it should rise to overflow, it can pass off by the lead waste-pipe ƒ, which secured and movable at pleasure in a ground-washer n, whose upper is made flush with the upper surface of the bottom a. After the water entered the cistern, it gets leave to settle its sediment, which it may do the height of the upper end of g. The sediment is represented by m, a when it accumulates to h, the cover c should be taken off, and the wast pipe ƒ removed, and the cistern cleaned completely out by the washer The waste water runs away through the air-trap o, and along the drain It is more convenient to have two small than one large cistern-as, wh the water is rising in the one, that in the other gets leave to settle. T cost of such a cistern, with droved stones, and to contain 18 cubic feet, wi the proper mountings, may be about £5. I think it right to say, in co mendation of this form of water-cistern, that in no case have I known th water about the plug to be frozen, in consequence, perhaps, of the non-c ducting power of the mud in the bottom of the cistern. The rod i has som times become fast to the ice on the top of the water at 7, but a little boilin water poured down by the side of the rod through the hole in the cover, means of a funnel, soon freed it from restraint."

A barrel will form a very excellent water-cistern. It should be sligh charred in the inside: this will prevent the wood from rapidly decaying and it tends to keep the water sweet. The charring will be easily effect by burning a few chips and shavings in the interior. The water can withdrawn from the cistern by means of a simple cock, or even more simp by withdrawing a plug driven into an aperture in the side of the cister about 6 inches above the bottom level-(See IRONMONGERY).