Most Viewed

- Browns And The Cold Semi-neutral Grays Marrone Is Practically To
- Also Called Scarlet Chrome Is A Bright Chromate Of Lead Of An
- Black Chalk
- Composition Chemical Analysis Has Shown Several Of The Blues To Be
- Burnt Verdigris
- Belong The Dutch And Flemish Schools; The Sensible Which Aims At
- Less Known As English Red Prussian Red And Scarlet Ochre True
- Olive In Dark Green; Russet And Citrine In Dark Orange The
- Known Likewise As Raw Sienna Earth Terra Di Sienna &c Is A
- Root Of The Anchusa Tinctoria Commonly Known As Alkanet A Plant

Least Viewed

- Their Chief Source The Greens Consist Of Yellow Mixed With Copper
- Only That Of Extreme Light Objects Opaque It Follows That White Is To
- To Which The Various Appellations Have Been Given Of Thenard's Blue
- Thallium Orange
- Distilled Verdigris Or More Properly Refined Verdigris The Best Is
- Molybdenum Green
- Red And Blue In The Proportions Of Five Of The Former To Eight Of
- Violet De Mars Purple Ochre Or Mineral Purple Is A Dark Ochre
- Uniform Colour Thus Composed Is The Citrine Colour Of Fruit And
- Also In The Olive Foliage Of The Rose-tree Formed In The Individual

Gold Purple

Purple of Cassius, or Cassius's Purple Precipitate, was discovered in
1683 by Cassius of Leyden. It is a compound of tin and gold, best formed
by mixing aqueous perchloride of iron with aqueous protochloride of tin,
till the colour of the liquid has a shade of green, and then adding this
liquid, drop by drop, to a solution of perchloride of gold, which is
free from nitric acid and very dilute: after twenty-four hours the
purple is deposited. When recently prepared, the colour is brightened by
boiling nitric acid. Not brilliant, but rich and powerful, this purple
varies in hue according to the mode of manufacture from deep crimson to
murrey or dark purple: it also differs in degrees of transparency.
Working well in water, it is an excellent though costly pigment, once
popular in miniatures, but at present rarely, if ever used, as purple
madder is cheaper, and perfectly well supplies its place. Retaining its
colour at a high red heat, it is now confined to enamel and porcelain
painting, and to tinging glass of a fine red. If, whilst in its hydrated
state, it be washed with ammonia, a bright purple liquid results, from
which a violet colour, somewhat less expensive, can be produced, by
combining the gold purple with alumina, and calcining the product in the
same way that is practised with cobalt. This compound may be exposed to
the action of the sun's rays for a year without being sensibly affected.





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Previous: Cobalt Purples

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