On the combinations of fixed oil with nitric acid and the nitrates of mercury

Abstract

In this paper, Mr Reid explores the chemical interactions between fixed oils (notably lard and olive oil), nitric acid, and the various nitrates of mercury. He details the processes by which nitric acid partially decomposes when heated with lard, releasing nitrous gases and producing an oxygenised lard that combines with residual nitric acid to form a compound he terms nitrated lard. When nitrate of mercury is introduced, the reaction yields a yellow ointment—known as ointment of nitrate of mercury—whose properties depend upon the relative proportions of the pernitrate and pronitrate of mercury present.

Reid provides precise experimental observations of acid–base neutralisation, precipitation reactions, and colour changes, using these to infer the chemical composition and behaviour of the resulting ointments under heat and storage. He argues that commonly prepared mercurial ointments often contain uncombined acid and unstable nitrates, which may alter colour and efficacy over time. Reid proposes refined preparation methods—beginning with purified nitrated lard and pernitrate of mercury—to yield a chemically uniform and stable compound devoid of free acid or decomposable salts.

The study demonstrates a sophisticated application of analytical chemistry to pharmaceutical practice, bridging the gap between theoretical chemistry and medicine. It further highlights early efforts to standardise chemical preparations in colonial scientific contexts through experimental rigour and careful observation.