Chemistry is a science of analysis and synthesis. This simple statement characterizes chemistry as an art that breaks down the ‘nature out there’ and puts it back together in a form convenient to our use. It hides the fact that chemical substances are products of the analytic and synthetic methods invented at particular places and times in history. Objects of chemical inquiry are not a random collection of natural and artificial substances but are constituted by the stable laboratory procedures that shape chemical worlds. Recent concession to the historical contingency of chemical theories falls short of acknowledging this material contingency of chemical realities. To the latter end, this paper highlights how French chemists consolidated the analytic-synthetic ideal of chemical species... by making their evolving analytic methods compatible to each other through a series of theoretical moments and thereby stabilized their objects of inquiry, theory domains (composition, affinity, and constitution) and disciplinary terrain. Stabilizing chemical substances has always required normalizing the methods of identifying them and a comprehensive classification that naturalizes them.