Diagram, experimental equipment by J J [Joseph John] Thomson and R [Richard] Threlfall A diagram in black ink, with parts labelled A-H, showing the experimental equipment used by Thomson and Threlfall in their experiments on the production of ozone. The experimental setup is described in the paper as thus: 'ABC is a box made of flat pieces of glass about 1/16th of an inch thick, fastened together with paraffin; into the box two glass tubes, G and H, are inserted, the air entering the box through G, and leaving it through H. Against one side of the box a glass bottle, D, with flat sides, is placed and filled with water containing a little sulphuric acid, this serves as one electrode; the other electrode is a blackened tin plate, E, placed against the opposite side of the box, the distance between the electrodes being an inch and a half [...] The air entered the box through the tube G, having previously passed through a series of tubes and bottles filled respectively with phosphorous pentoxide, pumice moistened with sulphuric acid, and caustic potash; it was also freed from dust by passing through a tube containing a plug of cotton-wool. After passing through the box it bubbled through a test-tube, F, containing an iodide of potassium and starch solution, pieces of filter-paper moistened with this solution were also fastened to the sides of the box.' Subject: Physics / Electricity / Scientific apparatus and equipment A print of this diagram was published in volume 40 of the Proceedings of the Royal Society alongside the paper 'Some experiments on the production of ozone'. 1886