Red of Sorgho.

The Scientific American 21, 1865

Messrs. Editors: — Some papers give, as a new discovery the fabrication of a red coloring matter obtained from the stalks of the sorgho. This fact is not new, as the process to obtain it was described by Mr. Winter in the Bulletin de la Sicueté d'Encouragement, June, 1860, and I reproduced it in the Industrial Chemist, June, 1862, page 12. As it must interest many of your readers to know how to prepare it I send you a copy ot the article in question:—

"It is a fact long known that the sorgho contains a red coloring matter. The following in the process used by Mr. Winter to extract it: The trunks of the sorgho are stripped of their leaves and reduced to pulp in a rolling mill, and well pressed to extract the juice from them. This juice is used to make sugar or alcohol. The ligneous tissue is left some time to itself; it begins to ferment rapidly. Care must be taken that the fermentation is not too active, because by an elevation of temperature it will undergo putrid fermentation. When the operation has proceeded well, the mass, after fifteen days, has acquired a red or red-brown color. Stop the fermentation in drying well, and grind the matter to divide it.

"To isolate the coloring matter, infuse the powder in cold water, which dissolves a little coloring matter. Press the maw very strongly, and put it to macerate in a weak caustic lye. Filter, press and saturate the alkali by sulphuric acid; the coloring matter is separated in red flakes, which are collected on a filter, washed and dried. That color is nearly pure, very soluble in alcohol, alkalies, weak acids, etc.

"To dye wool and silk with it, use the ordinary tin mordant. The dyes made with that will resist the action of the light and a bath of soap moderately warm. The extraction and uses of that coloring matter are known and practiced in China, where the culture of the sorgho is carried on on a large scale."

Hoping this information will lead to the use of this coloring matter in industry, I remain, gentlemen, yours truly,
- H. Dussauce.

New Lebanon, N. Y., May 8, 1865.