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If a trace of furfural were present the turbidity had a brownish tinge, which is characteristic of the behavior of the reagent with aldehydes. According to Gross (6),alcohols higher in the series than methanol and secondary alcohols will also form a precipitate. TESTFOR FURFURAL Because of the volatility of furfural in steam (8) and the danger of its being carried over in the end portions, a specific test for this aldehyde was desirable. When 6 to 8 drops of the distillate were added to 0.25 cc. of an aniline acetate solution (3 cc. of freshly distilled aniline in 2 cc. of glacial acetic acid) a pink color occurred if furfural were present. The test‘wasfound to be sensitive to o*oool per cent Of Mueller (10) states that the test is accurate to 0.0005 per cent.
LITERATURE CITED Bates, Mullaly, and Hartley, J. Chern. SOC.,123, 401 (1923). Bergstrom, Svensk Kern. Tid., 34, 81 (1922); Chern, A h . , 17, 1181 (1923). Davis, IND. ENG.CHEM.,Anal. Ed., 1, 61 (1929). Friedrichs, Chern.-Ztg., 32, 890 (1908). Gross, Ann. fals., 18, 39 (1925). Hartley and Raikes, J . Chem. SOC.,127, 524 (1925). Jones and Amstell, Ibid., 1930, 131%. Menzies, Ibid., 121, 2787 (1922). Meunier, Mat. grasses, 9, 4516 (1916) ; Ellis, “Synthetio Resins and Their Plastics,” p. 218, Chemical Catalog, 1923. Mueller, J . Pharrn. chirn., 24, 224 (1921). Scott, Cook, and Brickwedde, Bur. Standurch J. Research, 7, 935 (1931). RECEIVED October 19, 1933. Contribution 100 from the Research Laboratory of Organic Chemistry, Massachusetts Institute of Technology.
Preparation of Microscopic Glass Spheres SAMUEL SKLAREW, Einson-Freeman Co., Inc., Long Island City, N. Y.
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N CERTAIN physico-chemical researches, as in the study of rates of diffusion of gases and liquids and of solids in gases or liquids, it is desirable to have per-
powdered glass. Gas from the main was fed to the other inlet of the burner. This blast lamp was placed at one end of a claygraphite cylinder, C, 6 inches in diameter, 3 feet long, and 1 fect spherical particles of known size and weight. Calcula- inch thick. Two blast lamps entered tangentially, facing tions are simplified since spheres are regular-shaped bodies, forward at a slight angle, so that their flame would swirl and whose physical constants are readily determined, and will a t the same time shoot forward down the cylinder. This kept pack in a regular geometric pattern leaving interstices whose the flames from one burner impinging on the second. Gas for dimensions are calculable. Glass lends itself readily to the these two burners was supplied by interposing a blower bepurpose. A given glass is uniform in composition. Its tween the gas main and the burner outlets. A Y-tube specific gravity and hence its weight may be determined if its supplied the necessary connections. Following the heat chamber was the settling chamber size can be measured. After a careful analysis of the problem, a procedure for the (D,Figure a), consisting of a horizontal metal pipe 3 feet in preparation of microscopic glass spheres suggested itself, diameter and 10 feet long, open a t both ends, fitted on the far I t was necessary to subject each fine particle of glass, in- end into a cardboard box 6 feet square, E. The box had sulated from every other particle, to a temperature sufficiently small holes punched in the top to allow the escape of air. high to insure its becoming a free-flowing liquid. At the The bottom of the pipe and box were lined with black paper same time the particle had to be kept in free suspension, in order that the glass spheres might be discernible after they until i t became solid enough not to change its shape on con- had settled. The pipe had a door fastened on the side to tact with other bodies. Air would insulate the particles allow easy access, and the box was so arranged that a flap from each other, and at the same time permit them to be could be opened to get inside. The heat chamber exit was heated until they were free-flowing. It would keep them in placed near the top of the settling chamber entrance in order suspension, if i t were moving rapidly enough, and allow that the molten glass particles might travel further before settling them to cool to rigidity before touching anything. After assembling the apparatus, a run was made. The APPARATUS gas cocks were opened to lamps 2 and 3 and the blower The apparatus designed by the author utilized such mate- started. The compressed air was turned on and the burners rials as were available and could be constructed at the mini- adjusted for maximum temperature and optimum position. T h e h e a t chamber was mum cost and effort. warmed to white heat. A system was constructed The wind turbine was then ( A , Figure l), utilizing a set in motion and adwind turbine with a hollow justed to maximum speed. shaft to churn the powdered The gas was turned on in glass while a powerful b u r n e r 1, a n d t h e comstream of compressed air pressed air released down descended the shaft and was the hollow turbine shaft. forced to pick up the glass The air s u p p l y was carepowder which was inclosed fully adjusted so that little in a bottle having t h e glass powder was picked up turbine sealed in it. A glass and carried into the heat tube led from the bottle to chamber. the next piece of apparatus, By v a r y i n g t h e speed B, consisting of a blast lamp, of the turbine and the air the air side of which conpressure down the shaft, nected to the outlet from the it was possible to control bottle containing the FIGURE1. DETAILOF APPARATUS
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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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153
w
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/
BLACK PAPER LlNiNG
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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