| Description | This volume is similar in purpose and content to volume A4 and consists almost entirely of ideas for future experiments and of personal written thinking about condensation phenomena. Its period of writing is coincident with the period of experimental work for which the laboratory records are contained in volumes A6 and A7 referred to above. The subject matter almost entirely concerned with the effects of ultra-violet light and of metals. There are frequent posings of problems, some of critical importance, thus on 7 July 1898, the question is asked- 'Are there any ions in normal air (permanently) or when exposed to sunlight?', the beginning of the recognition of cosmic ray ionization as responsible for the existence of condensation at the critical limits in the absence of applied ionizing agencies. From June 1898 to June 1899 there are about fifty pages of a fascinating consideration of a mixture of wide range of topics, such as the influence of ultra-violet light, electrification by freezing, by cleavage, by splashing, etc., together with numerous imagined devices for possible experiments. It must be admitted that much of this work never achieved the precise clarification which was obtained in connexion with Wilson's work upon natural condensation and upon condensation under the influence of X-rays and radioactive substances, but it is nevertheless of great interest as illustrating the flexibility of his mind, his habits of attempts at clarification by written summaries and questions, and his ingenuity in devising apparatus for experiments to test the possibilities which he imagined. In this section the possibility of maintaining a continuous supersaturation by mixing of jets is put forward. |