Uranium Red
:
ON THE PRIMARY, RED.
By treating the yellow sulphite of uranium with a prolonged current of
sulphuretted hydrogen, and saturating gradually with ammonia, a red
finally results. This colour is insoluble in water, and it has the
objection of remaining partially suspended for an almost indefinite
time, colouring the liquid light red. The product is brighter and more
beautiful while moist; when dried and powdered, its tone--slightly
approaching vermilion--is duller. The colour may be obtained of several
degrees of brilliancy, but, apart from the question of expense, it would
be inadmissible in oil, the red gradually altering by contact therewith.
The most persistent tint at length resembles burnt Sienna.