William Henry (1775-1836), English chemist. Henry was born in Manchester and was apprenticed to the Manchester Infirmary. In 1795 he went to Edinburgh and qualified as an MD in 1807. However, his own ill-health prevented him from practice so he devoted himself to chemistry. In 1803 he showed that the solubility of a gas in a liquid at a given temperature is proportional to the pressure of that gas above the liquid. This is known as Henry's Law. Henry also wrote papers on the analysis of various gases such as fire damp and illuminating gas as well as the composition of hydrochloric acid and ammonia. He was one of the founders of what eventually became the University of Manchester Institute of Science and Technology (UMIST).