4. Preliminary Note “On a New Method of obtaining very perfect Vacua.”

• Published in: Proceedings of the Royal Society of Edinburgh
• Main Authors: Tait, P. G., Dewar, James
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1875
• Subjects: General Engineering; Carbonic acid
• Online Access: http://dx.doi.org/10.1017/s0370164600029734; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0370164600029734

Professor Andrews, in the “Philosophical Magazine” for 1852, recalled the attention of physicists to the method originally devised by Davy of making a vacuum so perfect, that the residual gas exercised no appreciable pressure as registered by the depression of a barometric column. This he effected by filling the vessel to be exhausted with carbonic acid gas, having previously inserted a cup containing a concentrated solution of caustic potash. On rapidly exhausting with an air-pump, and leaving time for the absorption of the residual carbonic acid by the caustic potash, he obtained a vacuum as perfect as a Torricellian. Andrews' method was afterwards employed by Gassiot in his well-known investigations on the passage of electricity through attenuated media.