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hue. The best way of comparison is, by placing samplesof the dyed pieces flat, against a full light, that is, withtheir edges towards the light, and then going back alittle, so as to look partly down upon them, and partlyover the surface : this is the way in which the dyers judgeof colours. On viewing in this manner several samples ofblacks dyed on blue cloth maddered and unmaddered, Icould not perceive that they differed greatly from oneanother, but was convinced, that if the maddered onesare not inferior to the others, they certainly have noadvantage above them. In some of the old receipts,madder is directed as an ingredient in the black dye itself,along with the vitriol and galls ; but here it is evidentlysuperfluous, its colour not fixing itself in the cloth.Among the reasons alledged for the use of maddering thecloth, there is only one which appears to have any plau-sibility, viz. that it prevents the black cloth from stainingthe skin or linen; but all that the madder can do in thisrespect, as Mr. Hellot justly observes, is, to discharge thesuperfluous blue, and this not in virtue of the madderitself, but of the boiling with alum and tartar preparatoryto the madder dye. The same advantage may be ob-tained by sufficiently showering the cloth in the fullingmill after the dye. This is evident from the superfinecloths dyed by our dyers, among whom the injudiciousand unfrugal practice of maddering, from such informa-tion as I have received, appears to be unknown. Theyhave indeed a colour called madder black, dyed on baize,(a kind of coarse cloth stuff) fox Portugal and Spain;but this depends on' another principle, as will. appear here-after.

7. Logwood, which as we have seen in the foregoingsection is a very useful ingredient in writing ink, is stillmore so in the black dye. Vitriol and galls, in whatever

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