By the late eighteenth century, scientists had discovered certain types of gas, such as 'fixed air' (carbon dioxide), but their composition was little understood. Relatively few investigations into gases had taken place, and so the polymath Joseph Priestley (1733–1804) was able to make major breakthroughs in the field using a range of experimental techniques. While living near a brewery, he found that it was possible to outline the shape of the gas above fermenting beer with smoke, and that fire would burn with varying strength depending on the composition of the air. This three-volume collection first appeared between 1774 and 1777. Priestley acknowledges that Volume 3 (1777) would more greatly interest those with technical training in the physical sciences as compared with general scholars. It also highlights some new and important inferences, notably on the function of blood in respiration.
