What highly toxic substance was used in the manufacture of the popular Victorian colouring material Scheele's Green?
Carl Wilhelm Scheele Carl Wilhelm Scheele Carl Wilhelm Scheele (, ; 9 December 1742 – 21 May 1786) was a Swedish Pomeranian and German pharmaceutical chemist. Isaac Asimov called him "hard-luck Scheele" because he made a number of chemical discoveries before others who are generally given the credit. For example, Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, hydrogen, and chlorine before Humphry Davy, among others. Scheele discovered organic acids tartaric, oxalic, uric, lactic, and citric, as well as hydrofluoric, hydrocyanic, and arsenic acids. He preferred speaking German to Swedish his whole life, as German was
Hand-colouring of photographs to recreate the appearance and effects of hand-colouring. Colourisation is now available to the amateur photographer using image manipulation software such as Adobe Photoshop. Basic dyes are used in the hand-colouring of photographs. Dyes are soluble colour substance, either natural or synthetic, in an aqueous solution, as opposed to pigments which are generally insoluble colour substance in an aqueous suspension. Aniline dyes, the first synthetically produced dyes originally used for the dyeing of textiles, were first used to dye albumen prints and glass transparency photographs in Germany in the 1860s. When hand-colouring with dyes, a weak solution of dye in