A few years ago Massachusetts Institute of Technology (M.LT.) startled with the announcement that calcium chloride will disperse fog. The chemical is a well-known drying agent. As it is sprayed through air enough water is abstracted to clear the fog. Thus a corridor can be formed from 100 to 200 feet wide, 50 to 100 feet high and roughly a mile in length, so that with modern radio controls an aeroplane can be steered and landed in it. An experimental volume of 1,000 yards long, 100 feet wide and 200 feet high contains about thirty tons of water. It is enough to extract half a ton in the form of liquid droplets to clear the air. It costs about U.8.$5 a minute to keep a corridor clear.
What M. I. T. has been doing in fog research since this memorable announcement was made, Dr. Karl T. Compton revealed in an address delivered recently before the General Electric Science Forum.
"The first requirement was to find out a good deal more about what fog really is and how it behaves than had previously been known," remarked Dr. Compton. So what he calls a "fog microscope" was invented to study the distribution of sizes of fog droplets. In other words, it was necessary to discover how much water is in the form of liquid droplets and how much in the form of invisible vapour. Also to establish the chemical nature of fog droplets, since each is condensed around some nucleus of foreign matter. It turned out that foggy air contains far more invisible vapour than Visible droplets. "In an average New England fog," says Dr. Compton, "there is about sixty times as much water in the form of invisible vapour as there is in the form of droplets of water."
Text read from the printed page and cleaned; old type leaves the occasional error.