SAFETY FIRST IN STORING CHEMICALS1 H. F. DAvrsoN. BROWN UNIVERSITY, PROVIDENCE. R. I. "Chemicals should be treated with a great deal of respect." This statement which we hear so often and which is so obviously true, will bear repeating many more times, for the careless handling of chemical substances can produce serious consequences. When a disastrous fire occurs in a school building i t is very frequently traced to the chemical laboratory and the general verdict is "spontaneous combustion." It occurred to the writer that it might be interesting to investigate which of the substances generally found on stock-room shelves were likely to cause fires by their improper storage. Several combinations, not generally mentioned, that could easily have caused a wooden building to be burned, were met with, and they are here set down for the benefit of those who may not have happened to think of them in this connection. Such dangerous combinations as are well known, like sodium or potassium and water, considerable quantities of quick lime and water, concentrated nitric acid and turpentine (or wood), rags or waste covered with linseed oil, phosphorus and air, need not be spoken of a t length. Sufficei t to say that great care should be exercised in their storage and use. Phosphorus should be kept in a glass container which is placed in another container of metal, as the metal is less likely to be broken than the glass. Before leaving for any extended time (as for the summer vacation), the phosphorus in the double container should be set into as tone crock, covered completely with water and plwed in the sink. The crock should be covered to prevent evaporation. One will rest easier should a fire occur, if he knows he has taken these precautions. To demonstrate to yourself or to your students how a chance breaking of two bottles containing apparently innocuous substances, in combination with a leaky roof, might set fire to the laboratory, try the following experiment: On a sheet of asbestos spread a layer of dried ammonium nitrate (granular) making a flat disk of it about five cm. in diameter and five mm. thick. On this spread a smooth layer of zinc dust (also dried). .Make a cavity in the center of the layer so that the white crystals of the ammonium nitrate show through the layer of zinc. Now with a long rod or tube put one drop of water in the depression you made and await results. In a similar manner you can start a fire with equal parts by volume of powdered iodine and fine aluminium powder. These must be mixed dry by shaking in a bottle and will ignite with beautiful effect when slightly moistened. A mixture of equal parts by volume of sodium peroxide powder and fine 1
Paper read before the New England Association of Chemistry Teachers at Brown
Univ., Mar. 14, 1925.
VOL. 2, No. 9
SAFETYFIRST IN STORING CHEMICALS
783
shavings or fine planer chips will also ignite with great violence on addition of a drop of water. This shows the danger of dispensing sodium peroxide on filter paper, and the danger of stowing it away in wooden lockers where it may get wet. A pile made similarly will be set on fire by the stream of sulfur dioxide from a tank of this gas. It is a crime, I am told, punishable by fine of $30.00, in a certain laboratory to put a piece of charcoal into a locker. This is a wise and necessary precaution on the part of those in charge for nothing holds the heat like charcoal and it is nearly impossible to tell when the fire is all extinguished on it. Carbon disulfide is so easily inflamed that on one occasion we had a can of it take fire as i t was being siphoned through a rubber tube. No flames were near and the only explanation we have is that i t became electrified and a spark jumped into the vapor. Such a substance as zinc ethyl which is spontaneously inflammable should by all means be kept where, if it lights, it can do no harm and only small lots of it should ever be on hand. There is probably no new chemistry here for any who will read it, but possibly the thought of safety in storage will be quickened by those who try out some of the demonstrations here recorded.
X-Rays Will Speed Laboratory Analyses. Rapid anal&s of materials in the labaratory by the use of X-rays in a much shorter time than required by the older chemical methods, is promised by Prof. Urhain, of the Minero-Chemical Laboratory a t the ~ o h o n n e . With the assistance of Eugene Delaunay, he has just completed a series of tests of the X-ray method. The apparatus used is composed of an X-ray tube; a lead screen in which a small slot has been pierced; a "selector" of tantalum, as a filter for the rays; a stand to hold the ~ i e c to e be studied: and a detector t o measure the intensity of the radiation received -the inrcnsity I,emg indir:$ted by the diq,laremmt of :an i l l u r n i n ~ t d..pot The rnntrrial to he an;dyrrd is placed in the henm, and whcn it is in good condition, the spat of light remains stationary; but if a fault in the material appears, the electrometer registers promptly. By recognized laws of physics, the deviation is proportionate t o the amount of the fault in the matter. By this method, the smallest faults can be detected. For actual quantitative work, the movable holder for the material is replaced by a small basin. By using, for example, distilled water as a base, and placing this first in the basin to set the "zero starting point," other solutions containing salts can be analyzed by straight calculations. For more than one salt in solution, more than one wave length can be used. The great advantages of this would be first for the speed of analysis, and second that a constant watch and check can be kept on the material used in manufacturing. M. Delaunay, who did the actual work, also says t h a t there is no risk of error, which greater accuracy should prove invaluable.-Science Senice
