Paper, 'Experiments made upon metals with the Duke of Orleans his burning-glasse' by M [Claude Joseph] Geoffroy Paper by Geoffroy regarding experiments conducted using the Duke of Orleans' burning glass to examine the effect of heat on various metals, including iron, copper, tin, and lead. Geoffroy's conclusions were that the four metals were composed of a sulphur or oily substance and a metallic earth capable of vitrification. Subject: Chemistry Published in Philosophical Transactions as 'Experiments upon metals, made with the Burning-glass of the Duke of Orleans'. Read to the Royal Society on 2 November 1709. [1709]