Page:Treatise on Soap Making.djvu/60

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cid, or an alkali; but add a few drops more, of either the one or the other, the effect will be evident. If alkali is added, the test will be green; if acid, it will be red.

An intimate acquaintance with every particular relative to the leys, is the one thing needful for a soap-boiler, being as it were the ground-work of the whole operation, and materially essential to be well understood, before any attempt ought to be made at soap-making.

We come now, of course, to examine the leys already prepared, and to determine by experiment whether they are, or are not, fit for soap-making; that is, whether they are caustic and fit, or in a mild state, consequently unfit for the purpose.

Unless a soap-ley be rendered caustic, or deprived of its fixed air, it can have no natural attraction for vegetable or animal sub-

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