cachou de laval

Century Dictionary and Cyclopedia

1. n. An artificial dyestuff, first prepared in 1873 by fusing various vegetable and animal products, such as sawdust, bran, blood, and horn, with sodium sulphid. It dyes unmordanted cotton brown in a salt bath, and the color is fixed by an after treatment in a warm solution of some acid, as sulphuric, or a metallic salt, as copper sulphate or potassium bichromate. Various shades of a fast brown are produced, depending in character upon the after treatment. It is of interest as being the first of that important class of dyestuffs known as the sulphid colors.