This chapter builds on Newton's increasing interest in sulfur, placing his theories in the context of developments within the chymical community of the late seventeenth and early eighteenth centuries. It provides a new look at Newton's developing ideas about affinity and his role in the eighteenth-century development of affinity tables, the graphic representations of selective attractions by materials that cause those with less affinity to precipitate. Newton's attribution of refractive power to the sulfur content of illuminated materials justifies the view that he held a chymical theory of light. Nor did this fact escape his successors. In the years directly before the Chemical Revolution of the late eighteenth century, European chymists tried to push Newton's chymistry of light further by attaching his linkage of refractivity and sulfur to the phlogiston theory championed by Georg Ernst Stahl.