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Constant-Rate Dropping Funnel
HEMISTS are often annoyed to
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GILBERT ASHBURN AND ROBERT L. FRANK, Noyor Chemical Laboratory, University of Illinois, Urbana, Ill.
find. after c*refuUv adiustine a dropping funnel to deliver a liquid dropwise into a reaction mixture, that within a short time the flow of drops has either stopped entirely or greatly diminished. A combination of two factors may be held largely responsible for this: the diminishing hydrostatic pressure as the liquid Itvel falls, and t h e gradual tendency for the stopcock to close during the flow of the liquid. This conclusion o m be readily verified by experiment. A simple modification eliminates both these factors from an ordinary dropping funnel. "
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funnel. When liquid is allowed t o flow out, rir enters tube B and eseitlles at D. The pressure in t h e air space. C. then chanEes
of the Meriotte flmk ( 1 ) . The gradusl tendency of t h e st,opcock t o close may be obviated by restrict.ing the entrance of air into B and then opening stopcock G completely. The air flow can be controlled either by means of a capillary tube attached t o R or, 8 8 illustrated, H, by a screw clamp on a short piece of ruhher tubing into which hss been inserted a small wire, I: If the openinp- at F is of large diameter, it is sometimes neoessary t o draw out, the tube in order t o prevent air from entering at this point. Dropping funnels equipped in- this way have been found useful in this lahoboratory for the dropwise delivery of liquids into reaction mixtures. Although a slight decrease in rate can be noticed during the iime of delivery, the flow is constant enough for most purposes.
.. The modification. as shown i n the accompanying di+am, chiefly cow sists in placing tightly in the top of the funnel a one-hale s t m w r -4 ~, in which is inseke2 a glass tube, B, reaching nearly to the bottom of the ~
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LITERATURE CITED
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(1) ~ M u e l l e IND. ~, ENG.CHEX.,ANAL.Eo., 12, 171 (1940)
NEW EQUIPMENT S U l f U Ir
Train to 2 p.s.i.. then passes through an mtivsted charcoal lower m d into the air-purification furnace containing 8 heated stainless steel P t u b e 1 inch in diameter and approximately 4 feet long. filled with quartz ohipe. Air leaving the furnace is cooled to approximately room temperature by passing through a water-jacketed copper-coil oondenser 8t. the furnace outlet. It then passe8 sucoessively through watec. sodium hypobromite. and sodium hydroxide scrubbers, then through B eonstant-pressure regulator, into a moisture trap fitted into a vacuum bottle. and finally into a distribution manifold servina the suliur lamps. For the determination of sulfur in gaes, the spparatus ineludes eight Dureiumin weighing bombs of 35-ml. cepaeity. for mnnertinp to the sulfur I
Numbered smmg improved aprAratus acoelevated by the war program is a sulfur train. originated by the Universal Oil Products Co.
and built by the Precision Scientific Co.. 1736 North Springfield Am.. Chicago. The method, identified as U.O.P. Method H-201-43-A, determines 0,0002 to 0.05% of sulfur in oombustible liquids and gases. The samples are burned in a stream of purified sir and the product8 of oombustion absorbed in a solution of sodium hypobromite. The ' sulfur is then determined as sulfate by turbidimetric measurement of oolloidsl barium sulfate. The appeiretus consists of an air-pressure regulator and filter presm r e gage, air-purification furnsee. cooling tank, gas scrubbers. water regulator, moisture trap. and bank of eight A.S.T.M. sulfur lamps. Compressed air controlled by pressure-reducing valve is reduced
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