October 15, 1929
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
233
Device for Maintaining a Constant Rate of Flow of Liquids' John D. Sullivan SOUTHWEST
EXPERIMENT STATIOX, U. S. BUREAUO F MINGS,TUCSON-,ARIL
URIKG the courhe of leaching experiments that were being performed a t the Southwest Experiment Station of the U. S. Bureau of Mines in cooperation with the Department of Mining and Metallurgy, University of Arizona, it became necessary to devise means of maintaining a constant rate of supply of leaching solution. The ores were being leached by the open-drainage principle and required a supply of leaching liquor t h a t would keep the mass saturated and a t the same time not cause a flooding of the surface. A simple apparatus was developed which met all the requirements. It is especially valuable if a drop-by-drop rather than a continuous flow is desired. The construction of the apparatus is very simple, and the figure showing it is practically self-explanatory. A is a beaker, jar, crock, or other containing vessel of whatever size needed; B is a piece of wood cut in a circular 1 Received July 3, 1929. Published by permission of the Director, U S Bureau of Mines (Not subject to copyright )
form of diameter slightly less than that of the container, A; C is a cork which fits into a hole bored in the float, B; D, a piece of glass tubing bent so as to act as a siphon, passes through cork C and down into the solution in A . The size of the bore of D depends upon the size of drop desired. The siphon can be raised or lowered by moving the glass in C so that any desired solution head may be maintained. If a very slow drip is desired, the end of the tube, E, may be constricted. The constriction is at the end that is under solution rather than the outside end because otherwise the crystallization of salts might seal off the end. When a small container is used and the weight of D is so great that B is tilted from the horizontal, lead or other heavy material may be placed on the side opposite C. For this purpose a hole, F , may be bored part way through the float on the side opposite the cork and the amount of lead shot required to balance may be added. Once the desired rate of flow or drop is obtained by choosing a tube of the proper bore and by manipulating D to secure the required hydrostatic head, this rate can be maintained indefinitely. As the solution level drops, the float drops the same distance and the same hydrostatic head is maintained; likewise the same hydrostatic head is maintained when solution is added to the container. When the temperature changes, the viscosity of the solution changes, and the rate of siphoning is thereby influenced, but under ordinary room or laboratory conditions the temperature variations are not great enough to have much effect.
Buret Clamp and Holder' Marion Hollingsworth T ~ r OHIO i STATEUNIVERSITY, COLUMBUS,OHIO
'r
HE eonvenience of having bottles of standard solutions with burets attached to the bottles has led to the
development of the clamp and holder shown in the accompanying drawing. The part A is of wood 11 X 27 mm. (0.43 X 1.06 iiches) in cross section and somewhat longer than the scale on the buret which it is designed to support. The edges are slightly beveled towards the front so that A will remain rigid in the holder. The block B is of spring brass and wood. The cross section of the brass is 7 X 11 mm. (0.25 X 0.43 inch) and it is bent as shown in the detail drawing. The whole is made to slide easily on A and yet is held a t any position quite securely by the spring being reentrant a t C. The block D is similar to B but is fastened firmly to the end of A . All brass jaws are covered with rubber tubing. The holder is of wood 25 mm. (1 inch) thick, It must be long enough to carry the clamp past the sides of the bottle and wide enough to fit over the neck. It has been found better to make the neck opening quite large and then line it with cork to the proper size. One 6-mm. (0.25-inch) b& wikh wing nut is sufficient t o hold both holdw and Recd~dFebruary BE, 1029.
clamp in position. However, the holder is more rigid during adjustments if a small dowel pin is inserted in the end back of the bottle neck. The advantages of this clamp and holder are: (1) The entire buret scale is always free. (2) The buret may be removed or inserted with one hand. (3) The clamp may be used either end up, and when made long the buret may be placed in any elevation r e 1a t i v e t o the bottle-opposite, above, or below. (4) The buret is held so rigid that the upper end of the supply tube may be drawn to small bore and the end inserted through a grooved cork, set opposite the zero mark on the buret. This gives zero adjustment when the buret is filled and the pressure within the bottle is released.
