Scientific American 25, 17.12.1859
A. Winter, of Austria, has discovered a carmine-coloring matter in most parts of the Chinese sorgho, especially in the expressed stem, and has obtained a patent in Austria, Baden and other States. The process is as follors: The sorgho is pressed in the usual manner, and the empty cane piled up under cover in regular heaps, several feet high, and the dermentation which immediately sets in is so directed by more or less access of air as to prevent it from becoming patrid. After two weeks the whole mass is of a reddish brown or red color, when the fermentation is interrupted by drying. When dry, the mass is ground sufficiently fine, for the extraction of the coloring matter. It is covered in the proper vessels with cold soft water, and allowed to stand for 12 hours; but little of the pigment dissolves during that time. It is then drained and afterwards treated with a weak caustic soda or potash ley until this no longer extracts anything. This solution is carefully neutralized with sulphuric acid, thus precipitating the coloring matter in red flakes, which after settling is washed with water, collected on filters, and dried. This color dissolves in alcohol, alkaline leys, dilute neids, &c., and is employed for the dying of silks and woolens with the common tin mordants. The colors produced from it are said to be unchanged by light or by washing with warm soap-suds.
- Druggist's Circular