IRE extinguishmen"t by means of "man-made fog" is described in the current number (vol. 7, no. 3) of Mechanical Topics (International Nickel Company, 67 Wall St., New York City).
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From No.9 of the same volume we quote the following account of water-softening methods: "Geographers tell us that h"t(l-thirds of the earth's surface is covered with water and we have no reason to doubt their word. It is curious that we humans find such a commonplace material so alluring that, given a few days leisure, we gravitate toward a body of water as though in response to some physical law. And how we love to splash in it, to ride upon its surface, or to merely sit beside it and watch for hours, entranced by its changeless but ever-changing beau ty.
Two articles of real chemical interest are found in the current number (September, 1944) of The Monsanto Magazine (Monsanto Chemical Company, St. Louis, Missouri), generally considered one of the best of the trade journals. One of these, "The Gunga Dins of today," deals with the difficulties of supplying fresh water to our troops in the Asiatic theaters; the other, "Science and a tissue topcoat," concerns the use of paper impregnated with diphenyl for the protection of citrus and other fruits against spoilage.
"For all of its charm, however, we have learned that most waters are unsafe for internal enjoyment until they have been purified by mechanical and chemical means. Coarse, suspended solids can be removed by sedimentation or filtration; finely divided particles which do not settle may be eliminated by chemical coagulation processes; aeration removes dissolved gases some of which affect taste and odor; color is corrected by alum or carbon black; bacteria are killed by chlorination. Excessive hardness can be corrected by a number of chemical means including base-exchange methods.
In the fall Number of Research Today (Eli Lilly and 'Company, Indianapolis, Indiana) some of the recent chemical and clinical research on malaria is discussed, with some attractive illustrations.
"All waters, of course, do not receive full treatment. Many are by nature of such high quality that very little is necessary to render them potable. Others, unfortunately, really need more treatment than the taxpayer feels able to support. Softening of very hard waters, for instance, is commonly neglected.
In view of the concern over the rapid use of our oil supplies methods for the prospecting of new wells should be of great interest. Some of the old-fashioned (and modern!) contraptions for such prospecting, known as "doodlebugs," are described in the September, 1944, Shell News (Shell Oil Company, 50 West 50th St., New York City). The relation of petroleum to the production of synthetic rubber is being described and discussed everywhere-among other places in the July-August, 1944, Power Specialist (Johns-Manville Company, 22 East 40th St., New York City). Taken from a short article entitled "Gases in sunken ships" in the July-August number of What's New (Abbott Laboratories, North Chicago, Illinois): "The raising of sunken ships is a common task ill peacetime, but far more frequent and important during wars. All the technical jobs connected with this work have their hazards, but one which might not readily come to mind faces every member of the salvage crew who enters a compartment long filled with water or long sealed away from access to fresh air. Fermentations of many and varied kinds go on in sea water, especially in warm tropical seas and under conditions where an abundance of organic matter is present in a compartment firmly sealed against thc outside air."
Elsewhere in this issue is described the use of paper in the rocket-launching tubes of fighter planes. Another material used for this same purpose is magnesium alloy. The production of such tubes is the subject .of an article, "Boom-whish!!" in the September Dow Diamond (Dow Chemical Company, Midland, Michigan). In Silicate P's and Q's, vol. 24, no. 6 (Philadelphia Quartz Company, 121 S. Third St., Philadelphia, Pennsylvania), can be found an interesting account of the Pidgeon Process for production of magnesium.
"The chemical treatment of waters has a long history. One of the earliest cases is recorded in Exodus wherein is related the wanderings of the Israelites in the wilderness and how, after three days without water, they came to Marah but could not drink of its waters because of its bitterness. 'And the Lord showed him (M.oses) a tree, which, when he had cast into the water, the waters were made sweet.' Whether it was the tannic acid or some other t.:hemical which corrected the difficulty, we can still appreciate the sense of something miraculous which those poor sufferers must have felt when the,water was made potable, and a miracle, as the Archbishop of Rheims said to the 'Chamberlain in St. Joan" 'is an event which creates faith.' "Since those ancient days the purification of water has become a science, which, fortunately, continues to advance. One of the most interesting present-day treatments is that in which chemical solutions are added to raw water for the purpose of creating large fluffy floes which will settle slowly and, in so doing, carry down with them the tiny suspended particles which would otherwise leave the water slightly cloudy. Of the many materials such as sodium aluminate, ferric chloride, or aluminum sulfate which may be used for such a purpose it is the last, usually referred to simply as 'alum,' which is most commonly used. Only very small amounts are needed-as little as one or two ounces to a thousand gallons are often sufficient. Curiously, a very muddy water carrying large dirt particles will sometimes be clarified by less coagulant than a clearer \vater carrying suspended particles of very sl11all size. "Although the coagulant is added as a nea.rly clear solution, in alkaline waters it dissociates and coalescence of the molecules takes place rapidly to form gelatinous particles in which mud and bacteria are enmeshed. Gentle agitation is maintained for an hour, more or less, permitting the particles to grow into sizable floes before they settle to the bottom. "Sometimes the alum is inadequate for a particular type of water and then coagulant aids are called for. Certain clays may be useful on the theory that they. like the particles of suspended dirt, are negatively charged and are thus effective in neutralizing the positive colloids produced by alum in solution. The negatively charged silica sols are very much better for this purpose."
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