Either together or successively he held the offices of inspector of mines, professor at the School of Mines and at the Polytechnic School, assayer of gold and silver articles, professor of chemistry in the College de France and at the Jardin des Plantes, member of the Council of Industry and Commerce, commissioner on the pharmacy laws, and finally professor of chemistry to the Medical Faculty, to which he succeeded on Fourcroy's death in 1809.
William Speer was supervisor and chief assayer of spirits in the port of Dublin.
He had been a member of the consultative committee on arts and manufactures since 1805; he was attached to the "administration des poudres et salpetres" in 1818, and in 1829 he received the lucrative post of assayer to the mint.
Prismatic borax is found widely distributed as a natural product (see below, Mineralogy) in Tibet, and in Canada, Peru and Transylvania, while the bed of Borax Lake, near Clear Lake in California, is occupied by a large mass of crystallized borax, which is fit for use by the assayer without undergoing any preliminary purification.
To simplify calculation and to enable the assayer to use the metric system of weights employed in all chemical calculations, the "assay ton" ("A.T."