[ 39 ] SECTION IV. Examination of the Add of Spur, when feparaied from its bafts. 25, THIS acid cannot be diftinguifhed by the jfmell from the muriatic acid-, but it differs however materiady from it ; becaufe, when united with a calcareous earth, its common bafis, it forms a folid fubdance ; whereas the muriatic acid of fea-falt, when combined with fuch a calcareous earth, remains always fluid. 26. This acid may be reAified by diftillation, in a very gentle heat. That part of it which came over laft was by much the ftrongeft, and formed a hard cruft on the furface of that which came over firft. The veffels employed in the opera tion were corroded. The redtification being again repeated, the fame appearances happened; from whence it may be concluded, that the whole acid may be converted, by the addition of water, into flex. SECTION V. Acid of Spar, when treated with Alkali. 27. THIS acid being mixed with oil of tartar, formed a gelatinous fubftance, which did not cryftallize. This being infpiflated to drynefs, a faline mafs was left, which was about a fixth part of the alkali originally employed. The fyrup of violets did not change colour from this mix ture. Lime-water being added to it, a precipi tation