March 15, 1934
INDUSTRIAL AND ENGINEERING CHEMISTRY
the amount of glass passing through the heat chamber and also the speed as it was carried along by the wind stream. The apparatus was run in half-hour periods and the glass spheres were collected from the black paper lining where they had settled. The larger balls were, of course, nearer the heat chamber, while the smaller were a t the farther end of the box. Some were even on the sides and top inside of the box, where they had floated on the air stream. Examination under the microscope gave the size range from 0.01 to 0.00001 inch. There were about 95 per cent perfect spheres, about 4 per cent egg-shaped particles, and about 1 per cent deformed particles among the larger sizes. The percentage of perfect spheres increased in the finer sizes, until the very smallest were all perfectly spherical in shape. From any given section of the settling chamber the particle size varied very little. A re-run of the larger sizes would probably bring the percentage of perfect spheres nearer 100. USES OF SPHERES Aside from the uses mentioned above, the following have been suggested : 1. In the preparation of porous plugs or filters for use in a study of such problems as (a) the recovery of petroleum from underground sand deposits by displacement with water, aqueous solutions, gases, etc. (1); (b) diffusion of gases in long columns where major eddy currents could be prevented
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FIGURE 2. SETTLING UNIT
and longer heat chamber would lengthen the time of heating and permit incompletely converted particles to be converted to spheres. The wind turbine mixer and the glass-air jet could be redesigned for greater efficiency. Continued experimentation would determine the optimum conditions and apparatus.
PHOTOGRAPHIC DATA The illustrations for this article were made on Press 2000 plates, triple emulsion, the exposures running from 15 to 30 seconds with a 60-watt source of light brought to a focus with a plane mirror and a s u b s t a g e condenser. The plates were deieloped under red light in Eastman D11 contrast developer for 7 minutes, fixed, and washed. The p o s i t i v e s were printed on Azo paper with D72 developer. Because of t h e i n a d e q u a c y of photographic apparatus and technic, it was impossible to photomicrograph the very small particles, some of which were a small fraction of the size of that shown in Figure 3.
ACKNOWLEDGMENT The apparatus was collected and the experiments were done in the labora1 Partial conversion. Poor conversion from 2, Diffractlon pattern Conclusive evidence of tory at Nichols Chemistry Building at spherical shape of particle. Diffraction pattern g r o h d t o spherical glass takes place when the New York University, where the reand outer edge are both perfectly circular under particles are shot a t too high speed through heat chamber. Close examination will reveal very tiny the microscope. This particle presented a beautisearch was done under the direction of particles in close contact with spheres. These ful display of colored rings, unreproducible in particles are not round and seem to adhere through . Close examination will reveal two H. J. Masson, t o whom t h e a u t h o r and possibly a third in the dark band. electrical charge. They can be removed by carefeels greatly indebted. ful manipulation with a glass hair under the mi(5418 diameters. Original 0.00066 cm.) croscope. (1323 diameters) The author is especially indebted FIGURE 3. PHOTOMICROGRAPHS OF GLASSSPHERES to Arthur Liebers for assistance in editing this article, to C. C. Clark for by a packing of uniformly small spheres; ( c ) the filtration of the loan of apparatus which made possible the illustrations, liquids, destructive to ordinary filtering media; (d) filtration and to Robert Irving Langer for the sketches of the apparatus. problems where filter cakes of material having a known uniLITERATURE CITED form size are desired, etc. 2. In studies of sedimentation phenomena such as rate of (1) Bur. Mines, Circ. 6737,27 (1933). settling, settling equilibria, Brownian movement, etc., or where uniformly sized spherical particles would be an ad- RH~CEIVED August 2,1933. junct to lecture demonstration or instruction. 3. I n studies of certain adsorption phenomena where FLEXIBLE GLASS. A flexible form of plate glass, produced by large surfaces of known value are desired. secret process in one of the largest glass factories in Great 4. studies of fluid flow where stab]e suspensions of aBritain, is claimed to be meeting with considerable success, acsolid spherical particles having a different index of refraction cording to a reportmade public by the commerce Department. from the fluid under consideration would permit fluid moveThe new glass is flexible to a remarkable degree, and capable of withstanding enormous pressure. In a recent demonstration, ment to be observed, etc. a Plate of the glass measuring 3 feetin length was raised on two With a large enough settling chamber so arranged that eddy narrow boards. Pressure was then applied, causing the glass to currents were eliminated, no trouble should be entertained in curve, but upon removal of the pressure the glass resumed its obtaining a size separation of particles by settling. A wider normal straightness.
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