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dark brow n, or black colour. /;/, or rather through thisthin inky ground, the outlines were traced with a firmbut pliant fiyle, which they called Ceft rum ; if thetraced line happened to be incorreCt or wrong, it wasgently eftaced with the finger or with a fponge, andcafily replaced by a frefh one. When the whole defignwas fettled, and no farther alteration intended, it wasiuftered to dry, was covered, to make it permanent,with a brown encauftic varnifh, the lights were workedover again, and rendered more brilliant with a point ftiltmore delicate, according to the gradual advance frommere outlines to fome indications, and at laft to mafiesof light and fhade, and from thofe to the fuperinduc-tion of different colours, or the invention of the Poly-chrome which by the addition of the pencil to the ftyle,raifed the mezzotinto or ftained drawing to a legitimatepicture, and at length produced that vaunted harmony^the magic fcale of Grecian colour [ft).

If this conjecture, for it is not more, on the procefsof linear painting, formed on the evidence and com-parifon of paflages always unconnected, and frequentlycontradictory, be founded in faCt , the rapturous aftonifh- ment at the fuppofed momentaneous production of the

Hercu-

(b) This account is founded on the conjectures of Mr. Rian, in his Treatife ondit Maltrey der Alien, or the Painting of the Ancients, 4to. Berlin, 1787-