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

Ochre Browns

The slight affinity of sulphur for yellow ochre, with its merely
temporary effect thereon, was observed in the eighth chapter, where
allusion was made to the action of sulphuretted hydrogen and sulphide of
ammonium on the earth. Sulphur alone, and in the dry state, ignited with
yellow or other native ochres converts them into browns, varying in hue,
and of greater or less durability. Those browns, however, which we have
made by this process, although standing well in a book, have not
withstood exposure to light and air. They have all become pale, whitish,
or of a drab cast, evidently through the oxidation of the sulphur, or
rather the sulphide of iron formed during the calcination. Practically,
therefore, ochres have an antipathy to sulphur, moist or dry, by itself
or in combination; and are, so to speak, the disinfectants of the
palette. Ever waging war against sulphurous vapours, the native earths
serve to protect a picture from the damaging influence of impure air,
whether they be used alone, or employed in admixture with such pigments
as are injured thereby.





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