text: William Clark Still (born 1946) is an American organic chemist.  As a distinguished professor at Columbia University, Clark Still made significant contributions to the field of organic chemistry, particularly in the areas of natural product synthesis, reaction development, conformational analysis, macrocyclic stereocontrol, and computational chemistry.  Still and coworkers also developed the purification technique known as flash column chromatography which is widely used for the purification of organic compounds.