gems, Arabic mineralogy, early lapidaries

Ruska presents a German translation, with extensive introduction and commentary, of al-Rāzī’s important alchemical work Kitāb al-Asrār (Book of Secrets), which Ruska published under the title Geheimnis der Geheimnisse. The work is notable for its practical and systematic treatment of laboratory chemistry rather than the allegorical approach characteristic of much later alchemical literature. Al-Rāzī classifies the substances employed by the alchemist, including metals, minerals and ores, stones, salts, vitriols, boraxes, sulphur and arsenic compounds, describing their appearance, properties and suitability for particular operations. He separately discusses laboratory apparatus and furnaces and gives detailed accounts of such procedures as distillation, sublimation, calcination, solution, evaporation, filtration, melting and amalgamation. Of particular mineralogical interest are descriptions and classifications of naturally occurring substances based on observable physical characteristics; these include several varieties of sulphur and manganese minerals. The text provides important evidence for the sophisticated practical chemical knowledge of the Islamic world around the turn of the tenth century and for al-Rāzī’s attempt to organize this knowledge systematically. Ruska’s introduction and notes examine the Arabic manuscript tradition, terminology and relationship of the work to other writings attributed to al-Rāzī. Modern scholarship distinguishes the Kitāb al-Asrār translated here from a shorter supplementary work actually entitled Sirr al-Asrār (Secret of Secrets); Ruska’s title consequently contributed to the subsequent confusion between the two works.