Photograph, 'The apparatus employed' by W H Pendlebury and Margaret Seward A photograph showing the equipment used by Pendlebury and Seward in their investigations into the interaction of hydrogen chloride and chlorate in presence of potassium iodide. The photograph is annotated and a diagram of a thermometer is drawn below it. Subject: Chemistry / Scientific apparatus and instruments A print of this photograph was published in volume 45 of the Proceedings of the Royal Society alongside the paper 'An investigation of a case of gradual chemical change: the interaction of hydrogen chloride and chlorate in presence of potassium iodide'. 1888