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BS-AC VIDA NG Uae E: a4

amined by the procefs defcribed§ 13, p- 508, it will remain untouched by the acid, and be found inthe filtre, after the calcareous earth diffolved in the acid thall have pafied through it, forming a part of the refiduum.

Take this refduum, therefore,—add to it nearly its weight of fixed alkali* previoufly diffolved in a confiderable quantity of wa- ter, and filtered;—digeft it ina warm bath, or even boil it for fome hours;—pour the whole into a filtre, while yet warm;—as the fluid paffes through the filtre, pour up- on it more boiling water;—as that pafles off, continue to add more water, till it comes through the filtre quite infipid and pure, and then let it run off entirely.

By this procefs, the vitriolic acid leaves the calcareous earth to unite with the fixed alkali(to which it has a ftronger affinity) and with it forms a vitriolated tartar:—this vitriolated tartar, and the fuperfluous alkali, are diffolved by the water, and carried through the. filtre along with it; fo that what remains behind is the earthy part of the gyp/um, and the heterogeneous matters contained in the original lime-ftone.—By

* Potatfh.

Vor, I. Pp pouring