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Known Likewise As Raw Sienna Earth Terra Di Sienna &c Is A








ferruginous native pigment, firm in substance, of a glossy fracture, and
very absorbent. It is of rather an impure yellow colour, and much used
in landscape, being very serviceable both in distance and foreground.
Unless proper skill is exercised in its preparation, the sienna has the
objection of being somewhat pasty in working. Being little liable to
change by the action of either light, time, or impure air, it may safely
be employed according to its powers, in oil, water, and other modes of
practice. It possesses more body and transparency than the ochres; and
by burning becomes deeper, orange-russet, as well as more transparent
and drying.

Raw sienna compounded with cobalt, indigo, or Prussian blue, and a very
little bistre, yields good sea greens, that with indigo being the most
fugitive. Alone, it is adapted for shipping, sails, baskets, decayed
leaves, brooks and running streams.

TTITLE STRONTIAN YELLOW,

To justify its name, should be a chromate of strontia, a compound very
slightly soluble in water, and not more stable than the zinc chromate.
The pigment, however, now sold as strontian yellow is usually formed by
admixture, and contains no strontia whatever. Its absence cannot be
considered a disadvantage, for the substitute possesses a durability to
which the original could lay no claim. Other things being equal, we
prefer an original pigment to one compounded, but a good mixture is
decidedly better than a bad original. A light primrose, clear and
delicate.

* * * * *

The foregoing comprise those yellows more generally employed, advisedly
or not, as the case may be. The following are for the most part not
commercially obtainable, a remark that will apply in ensuing chapters to
all numbered colours printed in italics. As a rule, these have become
obsolete as pigments, or have never been introduced as such. The former
could not well be omitted in a work of this kind, and the latter deserve
notice as being at least suggestive. At present, many of them must be
regarded as mere curiosities, being obtainable only from materials of
excessive rarity. In time, however, the sources whence they are derived
may possibly be found in greater abundance, and these now fancy products
prove of value to the palette. The new metal indium, for instance,
furnishes a bright yellow sulphide, like that of cadmium. The colour
could not be affected by foul air, and might possess other advantages
which would render indium yellow a desirable pigment. With regard to
those compounds available for artistic use, but which have not to our
knowledge been adopted, several are quite ineligible. It may be thought
that they are needlessly referred to, but they are mentioned as a
warning and a guide. Strange preparations have been offered as pigments,
and sometimes accepted, witness turbith mineral, iodine yellow, &c. In
these days of chemistry there is less chance for them, but they are
continually submitted to one's notice, their merits being enlarged upon
in proportion to their worthlessness. Through an exceptional ignorance
they may still gain a place, and it has been deemed, therefore, not
superfluous to allude to them. At the same time we do not pretend to
exhaust the list, any more than we claim to note all substances
possessing colour, but yet not admissible as pigments. Some there are
which do not retain that colour on drying; others, whose preparation
involves processes too nice, complicated, or expensive, for
manufacturing purposes. There are many colours, again, which exist only
on paper. We have too often found the imaginations of chemical writers
far more vivid than the colours they describe. Gorgeous yellows turn
out dingy drabs; dazzling scarlets dirty reds; and brilliant blues dusky
slates. As respects colours, most books of science need revising.





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