Page:Treatise on Soap Making.djvu/61

45, such as oil, tallow, or grease of any kind, so as to convert them into a soap. For the sole purpose, therefore, of extracting the fixed air from the leys, do soapmakers use quicklime. Depriving the mild alkali of its fixed air, renders it caustic, or of a burning, corroding quality, and of that peculiar nature that instantly attach themselves to all greasy substances, and converts them into soap.

The common vulgar notion, of using quicklime for its heat, is a mistaken idea, although I know it to be entertained by many soap-makers. Our most celebrated professors of chemistry, when preparing a soap-ley, generally slake and sift their lime; consequently, banish entirely all regard for heat in the lime; using warm water rather.