Читать книгу The Practical Ostrich Feather Dyer - Alexander Bartlett Paul - Страница 13

It is prepared by treating aniline oils successively with nitrous acid and arsenic acid, and one of an alkaline nitrate at about 212° Fah., for a short time. The product is extracted with boiling water, neutralized with an alkali filtered, and the color precipitated with common salt.

Pure hydrochloride forms thin reddish crystals, which are soluble in water and in alcohol, yielding a yellowish red solution. The most characteristic reaction of safranine is that when concentrated sulphuric acid is gradually added to its solution, the color changes to violet, then to blue, dark green and light green. Then, on diluting the solution with water, the same changes of color take place, only in the reverse order.

In feather dyeing safranine is used chiefly in making light colors of a pinkish hue; such as pink, terra cotta, and to give a tint to ecru, beige and such colors.