Page:Treatise on Soap Making.djvu/59

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it; yet, I believe, there are hundreds in the trade that know nothing at all about it: be that as it will, I say, they ought to know it; nor can any man discover when a soap-ley is totally deprived of its alkali, without its assistance.

It is prepared in the following manner: Take a parcel of the blue flowers of any vegetable, violets, for instance, or the blossom of the mallow; beat them with the edge of a knife, and squeeze the juice of it into a tea-cup; with a small brush, or hair pencil, lay over a sheet of white paper with this juice, and when dry it is fit for use. All alkalis will turn it green, and all acids will turn it of a red colour. A combination of them both to the point of saturation, will not in the smallest degree alter the colour of the test, because they are then said to be neutral, having neither the properties of an a-