Scientific American 18, 28.4.1860
- A patent has lately been taken out by C. H. Williams, of London, for obtaining a new coloring substance suitable for dyeing and calico-printing, from quinine, cinchonine, strychine, or brucine. These substances are mixed with caustic alkali, and distilled, by which operation a liquid of an oily appearance passes over. This liquid is then re-distilled at a temperature of 320° and 350°, and it is divided into two substances, the one passing over at the lower and the other at the higher temperature. The substance obtained at the highest heat is treated with an iodide or sulphate, to which are added water and ammonia in excess, when the mixture is boiled until the liquid assumes a deep purple color. When this liquid is afterwards applied to silk, it colors it a brilliant and permanent purple. The coloring matter is applied to the fabric in an alkaline solution, and as the coloring substance is not readily soluble in water, it is kept for constant use in alcohol. The portion of the distillate which has passed over at the lower heat is mixed with any alcohol radical compound, such as amyl, and is heated in a close vessel up to 250°, when water and the red oxyd of mercury are added; the mixture is then boiled, when the liquid passes through the shades of blue and lilac, and finally becomes a deep purple. The brucine to be used for making this color may be obtained from coal tar, by distillation and subsequent purification by sulphuric acid and alkalies, and it is finally distilled again. The coloring matter obtained as described is always dissolved in alcohol before it is used for dyeing; the fabric is boiled in the solution. For calico-printing the extract is required to be considerably concentrated and mixed with albumen.
Ei kommentteja :
Lähetä kommentti