INDUSTRIAL AND ENGINEERING CHEMISTRY
532
Summary Improved methods of determining and recovering gold and silver from dilute solutions are presented. As little as 0.01 mg. of gold or 1.0 mg. of silver is recoverable from solution in 40 liters of water, which is recovery of one part of gold in four billion and one part of silver in forty million parts of water. Gold and silver are quantitatively recoverable from COllOidal solution by the procedure outlined. to making determinations Of A procedure is silver-ion concentrations as used in water sterilization. Gold
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content of sea water, mine water, and certain ore leach solumay be estimated by methods described*
Literature Cited ( l ) Brandesf c,H.* 26r 962 (2) Kirkpatrick, Chem. & Met. Eng., 41, 373 (1934). (3) Scheibler, c., Ber., 2, 295 (1869), (4) Yasuda, M., J. Chem. floc. Japan, 2, 321 (1927). R E C B I V ~July D 6, 1937. Presented before the Division of Physical and I n organic Chemistry a t the 90th Meeting of the American Chemical society, San Francisco, Calif., August 19 to 23, 1935.
A Noncorrodible Circulating Device KENNETH A. FREEMAN AND P. J. THOMPSON Naval Stores Research Laboratory, University of Florida, Gainesville, Fla.
D
URING the progress of work in this laboratory a noncorrodible device that would circulate a liquid was needed. The apparatus shown in Figure 1 meets the requirements. It is made of glass and operates as described here :
s
7-25 I +1.7cm
52.Scm.
3.5cm.
175cm.
FIQURE 1. DIAGRAM OF APPARATUS
The lower end of tube A is placed in the liquid to be circulated and the suction from an ordinary laboratory water aspirator is applied a t B. The outlet tubes, H and J , are closed readily by placing the fingers over the ends or by stopcocks. Thus the apparatus is partially evacuated and the liquid rises in tube A until it reaches the air inlet, C, where the solid column of liquid is broken. The alternate bubbles of air and liquid empty into reservoir D. The liquid then passes down through stopcock E and tube F into well G. When the level rises above the lower end of F , H and J are opened. The liquid continues to rise in G and then flows out at H. When reservoir D becomes full, the excess liquid flows out the top into the large tube, I , which in turn empties into G. This prevents the liquid from rising high enough to be drawn out of suction tube B. However, the suction must remain moderate, so that the rate of inflow will not exceed the combined rates of outflow. The rate of flow from H may be regulated either by the amount of suction applied or by stopcock E. When the suction is regulated so that the flow becomes steady, the lift requires no further adjustment. A stopcock or piece of rubber tubing with a screw clamp, placed on delivery tube H , may be used to regulate the outflow. In this case it is necessary to provide overflow J in such a position that the liquid will return to the original container. The air inlet C may be readily adjusted if the tubes at this point make a ground joint. It is entirely satisfactory to insert a T-tube at this point and regulate the air flow by means of an attached piece of rubber tubing and screw clamp. The dimensions of the apparatus may be varied t o meet any particular need. The following limits of.operation can be obtained with the apparatus of the dimensions in Figure 1: The pressure difference a t B may vary between 7 and 31 mm. The rate of delivery a t H may be as high as 215 ml. of water per minute when the air inlet, C, is 1.5 mm. above the level of the liquid being raised. Water can be raised from a level 30 cm. below C. For raising liquids a greater distance, it is necessary to lower the position of C. Best results are obtained when C is close to the liquid surface. The use of this apparatus with some modification of the well, G, as a sampling device for solutions or suspensions is suggested. By altering the shape and dimensions of D as indicated by the dotted lines, a filter medium can be inserted. This would make i t possible to remove suspended material from the liquor. The device has been used in this laboratory to circulate the electrolyte through a n electrolytic cell. The height of the main reservoir gave sufficient head to keep a steady flow of liquid at all times, and the safety outlet permitted the setup to be left for hours at a time without attention. RECEIYED August 9, 1937
