corundum, properties.3, history.1, gems, Arabic mineralogy

A historical study by Henry Carrington Bolton of the twelfth-century Arabic scientific treatise The Book of the Balance of Wisdom (Kitāb Mīzān al-Ḥikma), attributed to al-Khāzinī. Bolton examines the work’s treatment of the balance, hydrostatic weighing and the determination of specific gravity, drawing on the Arabic text and earlier translations and studies. Of particular gemological interest are the tables and discussions of the specific gravities of precious stones and minerals, including such materials as emerald, rock crystal, cornelian, lapis lazuli and pearl. Bolton emphasizes the sophistication and accuracy of medieval Islamic experimental methods and shows that the treatise represents an important early contribution to quantitative mineralogy and the measurement of density. The paper was subsequently reprinted in expanded form as The Book of the Balance of Wisdom: An Essay on Determinations of Specific Gravity by the Arabians of the XIIth Century.