Minium Or Saturnine Red Is An Ancient Pigment By Some Old Writers





confounded with cinnabar, and termed Sinoper or Synoper. It is an oxide

of uncertain composition, prepared by subjecting massicot to the heat of

a furnace with an expanded surface and free accession of air. Of a

scarlet colour and fine hue, it is warmer than common vermilion, whose

body and opacity it possesses, and with which it was once customary to

mix it. Bright, but not so vivid as the iodide of mercury, it is more

durable, although far less so than vermilion. When pure and alone, light

does not affect its colour, which soon flies, however, on being mixed

with white lead or any preparation of that metal. By impure air, red

lead is blackened and ultimately metallized.



On account of its extreme fugacity when compounded with white lead, this

red cannot be used in tints; but employed, unmixed with other pigments,

in simple varnish or oil not rendered drying by any metallic oxide, it

may stand a long time under favourable circumstances. It is an excellent

dryer in oil, and has often been used as a siccative with other colours,

but it cannot safely be so employed except with the ochres, earths, and

blacks in general. Oils, varnishes, and, in some measure, strong

mucilages, are preventive of chemical action in the compounding of

colours, by intervening and clothing the particles of pigments; and

hence heterogeneous and injudicious tints and mixtures have sometimes

stood well, but are not to be relied upon in practice. Altogether, red

lead is a dangerous pigment in any but skilled hands, and has naturally

had a variable character for permanence. It is frequently adulterated

with earthy substances, such as brickdust, red ochre, and colcotha.





TTITLE VERMILIONS.





Mineralogique Of Paris Are Two Splendid Specimens Of The Stone In Mixing Colours With Colours He Produces Compound Colours Or Hues facebooktwittergoogle_plusredditpinterestlinkedinmail

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