> Imagine my pleasant surprise, when reading an old large format book I have, > I see an interesting image of a "breaking boule" and the photo credit was > Andrew Davidhazy. Salute! So, what is a breaking boule? Gregory, The book was View Camera Technique by Les Stroebel. A veritable "giant" in photographic education and my teacher and friend. A boule in the context of that application is a volume of liquid that floats on superheated liquid from which the bouls is made by catching the evaporating gas, condensing it and returning it just above the surface of the hot liquid. "Miraculously" the returning condensate, instead of merging with the bulk material often forms a thin vapor layer between the two and starts to float on it. As more and more condensed material is added to the small drop that started to float the volume gets bigger and bigger, sometimes approaching 50 cc or more, but eventually the thin vapor layer separating the two is compromised and the floating "boule" merges quite rapidly with the superheated bulk liquid. My task at the time was to try to learn as much about the behavior of boules and particularly to try to determine where the breakdown of the vapor layer preferentially started. I did this work in the late 1960s and much of what I did for the Distillation Research Lab directed by Dr. KCD Hickman (another fantastic person and to whom I owe a lot) was published in several issues of the Journal of the Society of Photographic Scientists and Engineers. Thanks for asking. It brought back happy memories. cheerio, andy
