nigre

chemistry

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July 1, 2026

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The term "nigre" refers to a dark, impure solution of soap formed during soap manufacturing as it settles from the neat soap. This term is distinct from "Nigrosine," which describes a group of azine dyes. Nigrosine dyes are typically bluish-black and are used in various applications such as coloring waxes, shoe polish, plastics, lacquers, and as wood stains. They can be oil-soluble, alcohol-soluble, or water-soluble depending on their specific form.12

Chemistry, as a science, explores the properties, composition, and structure of substances, which are made of chemical elements. These elements are composed of atoms, the fundamental building blocks of matter. Chemical reactions involve the rearrangement of atoms to form new substances.345

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soap and detergent
Boiling process
…percent water); the lower, called nigre, varies in soap content from 15 percent to 40 percent. Since colouring matter, dirt, salt, alkali, and metal soaps are soluble in nigre but relatively insoluble in neat soap, and since most of the impurities are dense and tend to settle, the nigre layer…
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…percent water); the lower, called nigre, varies in soap content from 15 percent to 40 percent. Since colouring matter, dirt, salt, alkali, and metal soaps are soluble in nigre but relatively insoluble in neat soap, and since most of the impurities are dense and tend to settle, the nigre layer…
Read More