‎"WILSON, C.T.R. - THE WILSON ""CLOUD-CHAMBER"".‎
‎On the Condension Nuclei produced in Gases by the Action of Röntgen Rays, Uranium Rays, Ultra-violet Light, and other Agents. Received October 29, - Read November 24, 1898.‎

‎(London, Harrison and Sons, 1899). 4to. No wrappers as extracted from ""Philosophical Transactions"", Vol. 192 - Series A. Pp. 403-453. Textillustrations. Clean and fine.‎

Reference : 42793

‎First printing of Wilson's second importent paper describing his further experiments with his ""Cloud Chamber"".""To the period 1895-1912 belongs the development of an instrument which to my mind is the most original and wonderful in scientific history.I refer to the cloud or expansion chamber of C.T.R. Wilson...It was a wonderful advance to be able to se, so to speak, the details of the adventures of these particles in their flight through the gas....""(Lord Rutherford).""C.T.R. Wilson had been developing his cloud-chamber, which was to provide the most powerfull of all methods of investigation in atomic physics. In moist air, if a certain degree of supersaturation is exceeded this can be secured by a sudden expansion of the air) condensation takes place on dust-nuclei, when any are present: if by preliminary operations condensation is made to take place on the dust-nuclei, and the resulting droplets are allowed to settle, the air in the chamber is thereby freed from dust. If now X-rays or radiation from a radioactive substance are passed into the chamber, and if the degree of supersaturation is sufficient, condensation again takes place: this is due to the production of ions by the radiation. Thus the tracks of ionising radiations can be made visible by the sudden expansion of a moist gas, each ion becoming the centre of a visible globule of water. Wilson showed that the ions produced by uranium radiation were identical with those produced by X-rays."" (Whittaker in ""A History of the Theories of Aether and Electricity."" II, p. 4).‎