A new metal, discovered by Sir H. Davy amongst crude platina; specific gravity, 11.. It unites easily with every metal with which it has been tried, except mercury: with gold or silver it forms a very malleable alloy, not oxidated by a high degree of heat, but becomes encrusted with a black oxide when slowly cooled; one-sixth of it does not perceptibly alter the colour of gold, but renders it much less fusible.
RlCE. A hard, white, farinaceous, and very nutritive grain, which grows in the East and West Indies, and other warm climates; it grows to the height of about 2 1/2 feet, with a stalk not unlike that of wheat, but fuller of joints, and with leaves resembling those of the leek. It branches out into several stems, at the top of which the grain grows in clusters, and each of them is terminated with an ear or beard, enclosed in a yellow rough husk. When stripped of this rough coat and a thin under-skin, the grain is shown to be of an oval form, and of a beautiful white colour. The native mode of shelling rice (or paddy, as it is called in the rough state) in India, is by placing it in a large hollow stone or mortar, and striking the loose grain with a conical stone or pestle, by which it is constantly forcibly pressed and disturbed; and thus, by persevering efforts, the husks are rubbed off. This process is, however, a very tedious and laborious one, and to remedy it, a variety of inventions have been successfully introduced and improved upon. The general practice, of late years, has been to employ millstones for depriving the paddy of the outer shell, the stones being set at such a distance apart as will detach the shell, without crushing the interior grain.
The stones are covered by a hoop or case, which entirely encloses them, leaving a space all round between the stone and the hoop of about two inches. In one side of this hoop is a hole, through which the busked rice runs out upon a fine sieve, kept agitated by the mills; in passing over this, the dust and sand are separated; it then falls into the winnowing machine, which separates the busk from the rice. There is one of these machines to each pair of stones, to separate the rice from the husk, in its passage from the stones to the bin.
The rice in this stage of the operation is more or less red, nothing more being done than the separation of the husk; after this, it is taken to the whitening machine, where the inside cuticle, or red skin, is detached. This machine consists of a stone of coarse grit, fixed on a spindle like a grinding-stone; the stone is.enclosed in a case made nearly to fit, leaving a space all round of about an inch between the stone and the inside of the case: this case is made of plate iron, and punched full of small holes, like a grater, with the rough side inwards; it is so contrived, that the case may go round with the stone, or it may remain still while the stone is turning. The rice is put in between the case and the stone at a sliding door, or opening in the rim; the space is about two thirds filled; the stone is then put in very rapid motion, making at least 250 revolutions a minute, by a strap. The case is allowed to turn very slowly; this changes the position of the rice, and every grain in succession comes into contact with the stone, and, rubbing hard against each other, an accumulation of heat (which produces an enlargement of the grain, and consequently splits the red skin) is produced, which serves to loosen the skin; and this, forming a red dust, finds its way out of the holes in the case, and leaves the rice perfectly white.
The cleansing of rice in this country is of modern introduction, and, from its apparently growing importance, we shall add some account of the processes recently patented for that purpose.
Mr. Ewbank's patent of 1819 informs us that the paddy is'first cleansed from foreign matter by passing it over a screen, which, detaining the rice, allow the impurities to pass through. The paddy in this state is taken to millstones, set at a proper distance apart to rub off the external shells or husks; the husks are next blown away by a fanning machine; the rice, thus partially cleaned, is then deposited in mortars, where it is beaten and triturated for depriving it of the thin red skin; and when the trituration has been carried far enough, the contents of the mortars are sifted upon a "sloping and revolving screen," which is composed of three distinct wire-cloths, of different degrees of fineness. The finest under cloth allows the dust or flour to pass through, but detains the broken rice; the second or middle cloth separates the broken, and detains the whole rice, while the coarsest upper cloth allows only the whole rice, or husked grains to pass through, and detains theunhusked, which is taken back to the millstones to be operated upon again.
The rice, still but imperfectly clean, is afterwards taken to the polishing and whitening machine, which consists of two cylinders placed concentrically; the exterior cylinder is fixed or stationary, and the interior one, which is made to revolve, is covered with sheep-skins with the wool on the outside. Between these two cylinders the rice is put, and the inner cylinder being made to revolve, the rice is brushed by the constant friction of the wool, and thereby polished and whitened.
A second patent granted in May, 1827, to Messrs, Lucas and Ewbank, relates to an improved method of treating the rice, that is, after it has been husked. For the purpose of depriving or getting rid of the red pellicle, which is united to the rice by a gummy substance, they employed in succession two or more sets of mortars. When, by the trituration of the pestles, the gummy or glutinous matter begins to disengage itself (which is immediately manifested by the rice moving sluggishly under the pestles), it is to be taken out of the first set of mortars, and carried to a second set, wherein is to be mixed with the rice a quantity of the external husks well dried, in the proportion of one fourth or two-fifths in bulk to that of the rice. The triturating and beating process is then renewed upon this mixture, the dry husks greatly assisting in cleaning and whitening the grain. After this the mass is to be fanned and screened, to separate the refuse; when the rice is taken to the polishing machine, as before described, which terminates the process.
In the month following the date last mentioned, Mr. Melvil Wilson, a merchant of London, took out a patent for an .improvement in husking rice, in which the operation was conducted simply by the collision of the grains of paddy against each other.
The apparatus consists of a long hollow cylinder, around the interior surface of which are fixed a series of angular bars, projecting towards the axis of the cylinder; this cylinder revolves loosely on a central shaft, which passes through it, and is provided with a similar number of bars, pointing radially from the centre to the circumference, and passing alternately between the bars in the cylinder, so as to leave an inch free space between them. Thus disposed the cylinder is placed in an inclined position; the rice is allowed to enter it at the top, while the cylinder is made to revolve with a "slow motion" in one direction, the axis moving at the same time at "a high speed," and in a contrary direction; consequently, as the rice passes through the cylinder, it will be considerably agitated and turned about; and the husk will, it is said, be rubbed off before passing at the lower end of the cylinder.
Fig. 1 represents a plan of the cap of the cylinder, not fixed thereto, nor to the axis, which passes through it, but to the framing which supports the hopper; it serves to guide the grain into the cylinder, and to keep out adventitious substances.
Fig. 2 is called, in the specification, "a socket wheel;" it is fixed directly under the cap to the cylinder, and the axis passes through the socket, whichserves, therefore, as a bearing for both the axis and the cylinder, permitting them to revolve freely in contrary directions. For the convenience of removal, this wheel is made to divide into two parts, which are bolted together when in use.
Fig. 3 gives a transverse section of the cylinder and axis, each of which being shown as provided with four bars, that number being fixed in each parallel circle, and alternately as respects those on the cylinder, and those on the axis. This section likewise shows the cylinder to be composed of eight distinct pieces or segments; on each of the eight segments is fixed a longitudinal row of similar bars, though only four (the number in one circle) are brought into view, to prevent confusion.
Fig. 4 is a transverse section of one of the before-mentioned bars, showing that they are of the figure of a quadrangular prism, that shape being preferred by the patentee for the purpose in question.
Fig. 5 is a plan of the bottom of the cylinder; it is formed in part like the socket wheel, described in Fig. 2, but the spaces between the spokes are closed; in each of these compartments a large aperture is made for the egression of the grain, which is regulated at pleasure, by sliding doors to each, as represented.
Mr. Wilson took out a second patent in 1830 for "an improved method of preparing and cleansing paddy or rough rice," which may be briefly described as consisting of a series of mortars with solid bottom and sieve sides; the latter being made of wire gauze, or perforated metal plates, strengthened by ribs of strong wire. These mortars are placed in a row, and their contents operated upon by a series of pestles suspended to a revolving crank shaft above, the pestle rods being guided in their action by a suitable frame underneath, sliding between upright standards which support the crank shaft. The intention of the "sieve sides" to the mortars is, that the rice may pass through as soon as it is cleaned, so as not to be heated by the subsequent operation of the pestles.
We shall mention one more patent, which was recently granted to Mr. Shiels, of Liverpool, for the same object. Instead of a pair of millstones for the first operation of shelling, the specification of this patentee directs the employment of one mill-stone, and what we will take leave to call one mill-wood (of precisely similar figure to the stone), and between these two substances the paddy is to be milled in the same manner as between two stones. The second operation of taking off the thin pellicle is to be performed by rubbing the grain between the flat surfaces of two wooden runners, which are covered with sheep-skin with the wool on. But Mr. Shiel's mode of applying the sheepskin is different to Mr. Ewbank's before described; the wool being placed by Mr. Shiel next to the surface of the runners, so that the rice is operated upon by the flesh sides of the skins, and owing to the springiness of the wool underneath, the grain receives an elastic pressure.