MARGGRAF, ANDREAS SIGISMUND.

Experiences qui concernant la Régéneration de L'Alun de sa propre Terre, l'apres avoir séparé par L'Acide vitriolique, avec quelques Compositions artificielle de L'Alun par le moyen d'autres Terres, et dudit acide. Traduit de l'Allemand. (+) Experiences faites sur la Terre D'Alun. Traduit de l'Allemand. (+) Continuation des Travaux sur la Terre D'Alun. Traduit e l'Allemand. (3 papers).

(Berlin, Haude et Spener, 1756). 4to. No wrappers, as issued in "Memoires de Academie Royale des Sciences et Belles-Lettres", Annee 1754, tome X, pp. 31-40 a. pp. 41-50 a. pp. 51-68.

First printing of 3 historical chemical papers.
"Stahlregarded alum as a compound of vitriolic acid and lime. Marggraf (1754) found that these substances produce only selenite (gypsum), whic is a salt, not an earth. To obtain alum he treated clay with sulphuric acid, but found that crystals were formed only when potash or ammonia was added, so that alum contains these alkalis. The 'earth of alum' (Alaun-Erde) is a peculiar one, present in combination with silica in clay. It is precipitated by alcali from Alum solution and, after drying in air, is soluble in acids, and is hence an 'alkaline earth'..."(Partington II, p. 727).

Order-nr.: 42710