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290 5. Wherefore, Fifthly, I conclude (as the most probable opinion) that the use of Allum is to be a Vinculum between the Cloth and the Colour, as clammy Oyls and Gum-waters are in Painting and Limning; Allum being such a thing, whose particles and Aculei dissolved with hot Liquors will stick to the Stuffs, and pitch themselves into their Pores; and such also, as on which the particles of the dying Drugs will also catch hold, as we see the particles of Copperas and other chrystallizing materials, do of Boughs and Twigs in the Vessel, where such Chrystallization is made. A second use I imagine of Allum in Dying, to be the extracting or drying up of some such particles, as could not consist with the Colour to be superinduced; for we see Allum is used in the dressing of Alutas or white Leather, the which it dryeth, as the Salt of Hen-dung doth in Ox-hides, and as common Salt doth in preservation of Flesh-meats; for we know, a Sheep-skin newly flayed could not be colour'd as Brasils are, unless it were first dressed into Leather with Allum, &c. which is necessary to the Colour, even although the Allum be, as it is, cleared out of the Leather again, before the said Colouration, with Bran, Yolks of Eggs, &c. Wherefore as Allum, as it were by accident, makes a wet raw Skin to take a bright Colour, by extracting some impedimental particles out of it; so doth it also out of other materials, though perhaps less discernably.

Another use I suppose of Allum, which is to brighten a Colour: For as we see the finest and most glassy materials to make the most orient Colours, as Feathers, Flowers, &c. so certainly if by boyling Cloth in Allum, it become Rh