Pyrophorus
Encyclopedia
The term pyrophorus refers to a substance which spontaneously inflames on contact with the air; one of yellow color and blue fluorescence
. In early use, the term was applied specifically to Homberg
's pyrophorus, a substance made by heating alum
with lampblack, flour
, starch
, or sugar
.
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
. In early use, the term was applied specifically to Homberg
Homberg
-In Germany:*Homberg , administrative seat of Schwalm-Eder-Kreis, Hesse*Homberg , in the district of Vogelsbergkreis, Hesse*Homberg, Westerwaldkreis, in the district of Westerwaldkreis, Rhineland-Palatinate...
's pyrophorus, a substance made by heating alum
Alum
Alum is both a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated potassium aluminium sulfate with the formula KAl2.12H2O. The wider class of compounds known as alums have the related empirical formula, AB2.12H2O.-Chemical properties:Alums are...
with lampblack, flour
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...
, starch
Starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
, or sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
.