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- Browns And The Cold Semi-neutral Grays Marrone Is Practically To
- Black Chalk
- Composition Chemical Analysis Has Shown Several Of The Blues To Be
- Also Called Scarlet Chrome Is A Bright Chromate Of Lead Of An
- Burnt Verdigris
- Less Known As English Red Prussian Red And Scarlet Ochre True
- Belong The Dutch And Flemish Schools; The Sensible Which Aims At
- 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

- Of Those Pigments Would Do The Rich Yellowness Entirely Disappearing
- &c As Well As Of The Semi-neutral Gray &c: It Therefore Is Changed
- Orange De Mars Is A Subdued Orange Of The Burnt Sienna Class But
- Green Ultramarine
- Yellow Is A Chief Constituent: Hence Brown Is In Some Measure To Shade
- Sensible Perfection It Attained Harmony Of Colouring And Effect In
- Tertiary Colours Are Three Only Citrine Russet And Olive
- Together Instead Of Blending Them On The Palette May Be Attributed
- With Regard To Colours Individually It Is A General Law Of Their
- Are The Negative Powers Or Neutrals Of Colours And The Extremes Of

Pitch And [greek: Kallos] Ornament The Blue Is Named Pittacal

The mode of separating pittacal has not been clearly described. Dumas
states, that when precipitated in a flocculent state from its solutions,
or obtained by evaporation, it closely resembles indigo, and, like it,
acquires a coppery hue when rubbed. It is inodorous, tasteless, and not
volatile; and is abundantly soluble in acetic acid, forming a red
liquid, which, when saturated by an alkali, becomes of a bright blue. It
is represented as a more delicate test of acid and alkalis than litmus.
With acetate of lead, protochloride of tin, ammonio-sulphate of copper,
and acetate of alumina, it yields a fine blue colour with a tint of
violet, said not to be affected by air or light, and therefore
recommended for dyeing.

Like indigo, pittacal is believed to contain nitrogen, but its ultimate
composition has not been accurately determined. Dumas considers it
identical with a blue product obtained in 1827 from coal-tar by MM.
Barthe and Laurent. If this be the case, its greater stability over
coal-tar blues and colours generally admits of doubt. That, however, has
yet to be ascertained. Our object in noticing this blue has been
two-fold: first, to direct attention to wood-tar as a possible source of
colour; and secondly, to point to pittacal as a possible substitute for
indigo, possessing greater durability.





Next: Zinc-cobalt Blue
Previous: Wood-tar Blue

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