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

Or Coeruleum Under The Name Coelin There Has Of Late Years Been

imported from Germany the cobalt blue with a tin base to which reference
has just been made. This comparatively new pigment--which likewise
contains or is mixed with gypsum, silica, and sometimes magnesia--has
the distinctive property of appearing a pure blue by artificial light,
tending neither to green on the one hand nor to purple on the other.
This advantage, added to its permanence, has conferred a popularity upon
coeruleum which its mere colour would scarcely have gained for it. A
light and pleasing blue, with a greenish-grey cast by day, it possesses
little depth or richness, and is far excelled in beauty by a good
aluminous cobalt. A certain chalkiness, moreover, somewhat detracts from
its transparency, and militates against its use in water. It is in oil,
and as a night colour, that coeruleum becomes of service, as our
present system of lighting picture galleries by gas affects the purity
of blues generally. If those galleries were illuminated by means of the
electric light, we have it on the authority of Chevreul that all colours
and shades would show as well as by day: the same purpose would be
answered by the magnesium light. Some artificial lights are the ruin of
colours; in the soda flame (alcohol and salt) for instance, yellow
chromate of lead appears white, while red ochre and aniline blue appear
black.

Like other blues of cobalt, coeruleum assumes a greenish obscurity in
time, but like them it resists for a lengthened period both the action
of light and impure air, although chemically it is more open to the
influence of the latter, owing to its tin base. In admixture it may
safely be employed, as well as in fresco or enamel. For stage skies,
&c., in high-art scenery, the blue is admirably adapted. Now that there
are so many scene-painters who are artists--and so many artists who are
scene-painters--in bringing Nature to the foot-lights the effect of gas
on colours is of importance.

TTITLE COBALT BLUE,





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