ing food; and which appear from his experiments to be nauseous, bitter, and cathartic salts, with earthy bases. And, as the mode of purifying salt by dissolution in water, and precipitation of the earthy matters with fossil alkali, is not only too tedious, but also too expensive for common use, Lord D. proceeds on the fact, that hot water, when saturated with sea-salt, will still dissolve some portion of bitter salts. He, therefore, directs the small end of a funnel, or similar vessel, which is perforated, to be placed downwards; filled with sea-salt, and kept in a moderate heat. One 20th part of such salt is now to be dissolved in the smallest possible quantity of boiling water, which must be poured into the cone, that contains the remaining 19 parts. The boiling water, being thus saturated, will not take up any more salt, but liquefy a considerable part of the bitter, earthy, or saline particles, which consequently will ooze out at the hole. When this solution ceases to drop, the process must be repeated, by using fresh portions of the same parcel of salt thus partially refined, till the requisite degree of purity be obtained. Lord Dundonald is of opinion, that three washings will render the British salt much purer than that obtained from any other country:—the superiority of such salt is evident both to the taste, and for its effects in preserving animal food and butter. This is an object of the greatest importance, and from the simplicity, facility, and cheapness of the above stated process, we trust it will shortly be introduced into more general practice.—Various other, though more complicated attempts, have lately been made by private individuals, to expedite and improve the preparation of salt, as well as to decompose it with a view to extract the soda: among these, we shall mention only the following patents: namely, Mr. George Hodson's, obtained in August, 1792, for his new method of separating fossil alkali from common salt; and also of separating the same substance from kelp; his second patent, granted in February, 1797, for an improved mode of effecting the same object; and likewise of extracting the mineral alkali from the muriatic acid, contained in rock-salt, common salt, brine, &c.;—Mr. James Manley's patent, dated July, 1801, for various improvements in the process of manufacturing salt. As, however, these different processes would not be generally interesting, and could be understood only by the aid of engravings, the inquisitive reader will consult the 2d, 10th, and 15th volumes of the Repertory of Arts, &c.
Uses: The value of salt for culinary purposes is well knpwn: it is likewise of peculiar service in preserving the health of cattle (see vol. i. p. 466-7), and particularly in preventing that most fatal disorder in sheep, the rot (see vol. iii. p. 510-11). Besides, salt is an excellent manure; as it is equally destructive to weeds and vermin: the most accurate proportion appears to be sixteen bushels per acre; but, if that quantity be exceeded, or doubled, it will produce effects diametrically opposite to those intended, and completely check vegetation.
With respect to its medicinal properties, common salt, when taken in small quantities, promotes the appetite and digestion; but, if
given
