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

Murexide

The red obtained from this substance created a great deal of interest
among printers and dyers on its introduction in 1857, or thereabouts.
For purity and brilliancy of shade it was not excelled by any other
colour, but not being able to stand the effects of air and light, its
employment was limited. We are not aware that murexide has yet been
brought forward as a pigment, and judging from its character as a dye,
it would scarcely enrich the palette. Dyes and pigments have much in
common, and a fugitive dye cannot be expected to furnish a permanent
pigment.

Murexide is produced by the action of ammonia on alloxan, which is
itself derived from the uric acid of guano by treatment with nitric
acid, and was known nearly forty years back to stain the fingers and
nails red. The first murexide sent into the market was a reddish-purple
powder, dissolving in water with a fine purple tint, leaving a little
residue undissolved. Owing to improvements in manufacture, it is now
capable of being prepared almost chemically pure, and with that green
metallic reflection peculiar to several coal-tar salts and the wings of
certain insects. When sulphuretted hydrogen is passed through a
concentrated solution of murexide, it is immediately decoloured; a fact
which renders it likely that murexide pigments would be as liable to
suffer from an impure atmosphere, as from exposure to light and air.

When an alkaline solution of murexide is precipitated by an acid, a
light shining powder results, called purpuric acid. This dissolves in
alkalies, and combines with metalline bases to form various coloured





Next: Compounds Termed Purpurates Among Them May Be Mentioned A Red
Previous: Manganese Red

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