FIRE CONTROL BY PARADOX* Recent discoveries indicate that we still have much to learn abou* so familiar a phenomenon as fire. By way of example, we found in our own laboratory not long ago that the insulation of the wires used on telephone switchboards could be flameproofed by applying a dilute suspension of selenium to the braided wire. Since selenium is closely related to sulfur and is itself combustible, its effectiveness in flame suppression .is extraordinary, and for it no satisfactory explanation has yet been found. We are now conqronted with another paradox in the recent announcement of Thomas and Hochwalt that solutions of such highly oxidizing agents as potassium nitrate (saltpeter), and even the chlorates and perchlorates of potassium, are far more effective in extinguishing fires, and especially oil fires, than water alone. Here, again, the explanation is still lacking, and for want of better understanding the amazing results are attributed to "catalytic" effect. In the investigation of this effect, compounds of practically every element capable of forming a water-soluble salt were studied, hut with one or more minor exceptions only compounds of the alkali metals appear t o possess this "catalytic" effect on combustion. Among these compounds those containing oxygen are the more effective. Comparative tests demonstrate the startling fact that a solution of such a powerful oxidizing agent as potassium perchlorate is five times as effective as one of potassium chloride and nearly twenty-five times as effective as a solution of common salt. These discoveries have already received practical application in a new type of portable fire extinguisher.
* From the Industrial Bulletin of Arthur D. Little, Inc.,July,
1928.
