One of the founders of modern chemistry, born in Paris; to prosecute his researches accepted the post of farmer-general in 1769, introduced in 1776 improvements in manufacturing gunpowder, discovered the composition of the air and the nature of oxygen, applied the principles of chemistry to agriculture, and indicated the presence and action of these principles in various other domains of scientific inquiry; called to account for his actions as farmer-general, one in particular "putting water in the tobacco," and condemned to the guillotine; he in vain begged for a fortnight's respite to finish some experiments, "the axe must do its work" (1742-1794).