Third Prenaration.—The earth, after being thus sub jected to these various manipulations, is now fit to be applied to the lathe. The man, who is employed for this work, ought to heat it well with his hands, taking care to extract the stones, even the smallest which he may meet with, as well as every other foreign body. He then forms it into lumps, which he applies to the lathes .to be made into vases or jars. The alcarrazas may be baked in any kind of turnacc used by potters. Those employed in Spain arc eighteen leet square in the inside, and live feet three inches high. The flame enters by a hole, one loot linir inches in diameter, situ ated in the centre. Such a furnace u ill contain 800 dif ferent pieces of different sizes, including 500 jarras. Pottery of notch greater strength than the alcarrazas may be baked in the sante furnace, if care be taken to keep up the fire for one or two hours longer. The al carrazas, which require to be only half baked, remain there ten or twelve hours, according to the tempera ture of the air, or the greater or less quantity of the fuel employed. Processes are followed in some of the pot teries of Spain, varying in sonic degree from the above routine; but they all depend on the same principles. After the earth has been pounded, it is suffered to ma cerate in a tub for twenty-finir hours; the whole is that mixed with a stick, and it is freed from the straws, or other foreign bodies, that lloat on the surface ; the stones and coarser parts of the earth fall to the bottom of the vessel, and the finer is drawn off by a hole four inches above it. The earth is then left to dry to a requisite degree, and is afterwards deposited in a moist place, to be employed as may be found necessary. In other ma nufactories, the earth, when dry, is ground below a rol ler, after which it is sifted, and the proper quantity of salt and water being added, it is then kneaded. The proportion of salt is not every where the same. In some places, the same quantity of earth requires a half less of salt. Care is always taken to choose earth of a proper quality, without ever having occasion to add to it a mix ture of sand. The same earth is employed also for com mon pottery ; the only difference is, that salt is added to the clay used for the alcarrazas, and that they are only half baked.
The Arabs were the first who introduced the manu facture and use of these vessels into Spain, where they arc now manufactured in several different places. They
are made, as we have seen, of different forms and various sizes, and arc generally of a grayish-white colour. The most celebrated place for this species of potter y, and that from which all the vessels of this kind, used at Madrid, are brought, is Anduxar, in Andalusia. The banks of a rivulet, called Pamusoro, which is situated at the distance of a quarter of a league from the above town, abounds with earth for making them.
There is not a single family in Madrid, and scarcely a house in all Spain, where alcarrazas are not in constant use. A kind of red vessel, called .buccaros, employed likewise to cool water, is also made at a place called Salvatierra, in Estremadura; but the earth being less porous, it is not so proper for the intended purpose. Besides, these vases communicate to the water a disa greeable argillaceous taste ; in which they differ little from the effect of the common filtering basins, or stones, used in England. Among the ladies of Madrid, these buccaros arc in great request, some of whom pound fragments of them, and mix the powder with snuff. Young girls have a particular fondness for this kind of pottery, and eat it when they are troubled with the chlorosis Vases of a similar kind to those above described, are employed in Portugal for moistening snuff. They are plunged into water, after being filled with that article, and the liquid, filtering insensibly through them, com municates to the ingredient enclosed, after a few hours are expired, the necessary degree of humidity.
The editor of the Journal ele Physique is or opinion, that the mixture of fossil meal with eonimon potter's earth might afford an useful substitute, both for the al carrazas and the filtering stones. The f).ysil meal is that of which the floating bricks of Tuscany are made, and which, according to the testimony of Pliny and Strati°, was anciently found in great plenty both in Asia and Spain. To the proposed use, however, of this sub stitute, the earthy flavour, which it would communicate to the water, has been thought a radical objection ; but this, we have seen, is an effect attending also the filter ing stones of England. See CootEit, Egyptian; Er A PORATION ; HYGROMETER. (E)