Bologna stone

Bologneser, tn. Bolognese, Bologna. — — Flasche, Bologna flask. — — Spat, Bologna stone. 

Strahl-antrieb, m. jet propulsion, -apparat, m. jet apparatus (as steam-jet injector, pump, or blower), -asbest, m. plumose asbestos, -baryt, m. radiated barite, Bologna stone, -blende, /. a variety of sphalerite. -dUse, /. jet nozzle. 

Alchemists in the early Middle Ages knew about some barium minerals. Smooth round pebble-like stones found in Bologna, Italy, were known as Bologna stones. When these odd stones were exposed to sunlight, or even a primitive reading lamp, they would continue to glow for several years. This characteristic made them attractive to witches as well as the alchemists. These stones are actually the mineral barite, barium sulfide (BaSO ), which today is a major source of barium metal. 

Barite is a barium sulfate, BaS04, with orthorhombic structure 2jm2jm2jm) where the sulfur is situated in tetrahedral coordination with oxygen, and barium in twelve-fold coordination with oxygen. The mineral barite is one of the first luminescent materials from which the famous Bologna stone was obtained. Nevertheless, up to today understanding of natural barite luminescence... 

Early in the seventeenth century Vincenzo Casciarolo, a shoemaker and alchemist in Bologna, noticed that when heavy spar is mixed with a combustible substance and heated to redness, the resulting mixture, which became known as the "Bologna stone, emits a phosphorescent glow. 

Father Athanasius Kircher said that the phosphorus was made by pulverizing the Bologna stone, mixing it with white of egg or linseed oil, and calcining it in a special furnace. He found specimens in the alum mines at Tolfa (59). Biographical sketches of Father Kircher were published in The Hormone in 1934. (109) and in the Journal of Chemical Education in 1955 (139). 

The Abbe Jean-Antoine Nollet, in his Legons de physique experi-mentale, mentioned the cold fight of the Bologna stone and the sulphurous odor which the flame imparted to it. The odor that the Bologna stone acquires on passing through the flame, said he, gives sufficient evidence that these natural sulphurs have been liberated from the terres-... 

J. W. von Goethe collected specimens of the Bologna stone at Paterno in 1786, took them back to Weimar, made many experiments with them, and in 1792 discovered that only the violet end of the spectrum caused the phosphorescence. Goethe said that in Bologna the little phosphorescent cakes prepared from the Bologna stone were called fosfori (94). The modem name of the Bologna stone is barite, barium sulfate. 

Johann Sigismund Elsholtz, 1623-1688. Scientific authority at the court of the Elector of Brandenburg. A pamphlet which he had printed at Berlin in 1676 is the earliest publication concerning elementary phosphorus and also contains descriptions of the previously known phosphors Bologna stone, Baldwin s phosphor, and emerald phosphor (green fluorspar). See also ref. (113). 

The first mention of barium compounds goes back to the early 17th century. Early records mention a Bologna stone, named for the city of Bologna, Italy. The Bologna stone glowed in the dark. 

For more than 100 years, researchers labored without being able to identify the elements in the stone. In 1774, Scheele announced the presence of a new element in the Bologna stone. Today, scientists know that the stone was a form of barite. Five years later, Scheele demonstrated that barite was also present in heavy spar. This dense transparent mineral closely resembles ordinary spar, a compound of calcium. 

A variety of baryte (. v.) used as a source of material for pigment production. Terry (1893), in a discussion of Baryta white, for example, says at Bologna, a nodular variety is foimd, called Bologna stone, which is notable for its phosphorescent powers when heated . The Bolognese shoemaker Vincenzo Casciorolus (1602), who discovered phosphorescence in the mineral baryte, is undoubtedly the cause of this phrase being used although he himself appHed the term lapis Solaris. 

Synonym for baryte q.v.) common in the mineralogical htera-ture. Undoubtedly also related to the term Bologna stone. 

---