This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Smoke. All flash-powders produce some smoke and in making more than one flash the greatest care should be taken to see that the room is cleared of the smoke before making the second exposure, otherwise under-timed negatives will result. Always open the windows at the top as the smoke rises to the ceiling and will soon work its way out.
Development. In developing negatives made in accordance with the above instruction, there will be practically no difference between the development of the daylight and the flashlight exposures. Full instructions regarding the development is given in Vol. II. There is one caution which may be given, however: As there is a tendency toward under-exposure in flashlight work, it is advisable to start development with a diluted solution, carrying the negative in this solution until you have ascertained whether or not the negative was correctly exposed. The contrasty lighting produced when working without a diffusing screen, will make it particularly necessary to use a diluted developer, which will soften the contrast.