All of Faraday’s work in the liquefaction of gases, the discovery of new hydrocarbons, the study of the changes of steel through the slight admixture of other metals, the improvement of optical glass, and the long list of results which are to-day represented in millions of tons of products from thousands of factories, were obtained within these four walls. And nothing could better illustrate the earnestness and modesty of the great chemist than a little anecdote which Professor Dewar, standing in the centre of the room, calls to mind. “I never met Faraday,” says he, “but Tyndall told me this story of him. The first time Tyndall entered this laboratory, Faraday led him to this point and said: ‘Tyndall, this is a sacred spot. This is the spot on which Davy separated sodium and potassium.’” The laboratory of to-day, however, looks very little like a scene of chemical industry. It has more the air of a machine shop, equipped with power and mechanical appliances of a very heavy kind. Instead of bottles and multi-colored liquids, all is metal and steam. The room is about thirty feet wide and fifty deep, the north front consisting entirely of glass windows opening on a well-lighted interior court. In the left-hand corner, at the back, is a large steam-engine, while a smaller one occupies the corner diagonally across. Shafts, wheels, and belting run to two large air-pumps and three steel compressors, each about the size and shape of a small travelling trunk, and used respectively for compressing oxygen, nitrous oxide, and ethylene. A fourth compressor, or double compressing chamber, is cylindrical in form, and is wrapped in thick white flannel. This is the source of the liquefied oxygen. The system which Professor Dewar has followed is not novel in its general principles, as he explains. Specifically, however, it contains many new inventions which he does not wish made public. They are mainly in the nature of stop-cocks and valves, which it took long study to invent, and which became perfect only after many failures and costly experiments. To liquefy oxygen, he simply used pressure at low temperatures; but as, up to 1878, both oxygen and nitrogen after repeated trials were looked upon as permanent gases, it may be imagined that the attainment of temperatures low enough was a problem which required an extraordinary command of mechanics as well as of chemistry to practically solve. [Illustration: PROFESSOR DEWAR IN THE LABORATORY OF THE ROYAL INSTITUTION. FROM A PHOTOGRAPH TAKEN FOR M’CLURE’S MAGAZINE BY FRADELLE AND YOUNG, LONDON.]