Circular Bath and Shaking Mechanism for Manometric Microapparati IIENRY A. LARDY, W. E. GILSON, JAMES HIPPL University of K’isconsin, Madison, V i s .
A circular bath and shaking mechanism for conventional Barcroft-Warburg miommanometers are described. The apparatus permits greater speed and ease of operation, because the manometers are rotated to the operator for reading. The shaking motion is such that manometers can easily be read while flasks are being shaken. The ciroular apparatus accommodates more nianorneteis than the conventional rectangular bath, :-et occupies much less floor space.
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ANOMETRIC techniques were first used to determine the rate of metabolic reactions in surviving tissucs by do Saussure (4. Based on the principlos of E. Warburg, Haldsnc, and Barcroft, these manometric procedures for studying tissue metabolism were placed an B practical working basis by Barcroft and 0. Warburg (1, S). Adaptations and variations of the original vessels and manometers have been made by Dickens and Simer, Dixon and Keilin, Summersan, and others (1, g), hut tho basic mechanism for shaking the vessels and the original eumhersome rectangular bath have remained essentially unchanged through the past 25 gears.
other pieces of equipment. It occupies much less floor space than the conventional roctangular model which must have free working space on three sides. The circular unit is much more compact and can accommodate more manometers than the rectangular bath because the entire periphery of the tank is used. Baths 22 inches (55 em.) in diamet,er accommodate 18 manometers. An addit.i.ional manometer may ho addcd for each diametor increment of 1.25 inches, as eaah manometer requires nearly 4 inches of space on the bath periphery. ‘ The apparatus will accommodate nine Summerson manomcters, and special holders for thcse have been devised. Tw-o types of shaking mechanisms which permit manometer readings to he made while the flasks are in motion have proved satisfactory during more than 3 years of heavy use in research and advanced laboratory classes. The mechanical parts of the apparatus are of rugged, simple construction and all working parts arc readily accessible. Thc two types of apparatus me shown in Figures 1 and 2.
Figure 1. Model I
A circular bath and shaking mechanism of new design offering several advantages over older models have now been devised for use with standard type mafiometers. The new apparatus excels particularly in its ease and speed of operation. The manometer carriage i., rotated to bring the manometers to the operator as they are read without interrupting the shaking. Current is Supplied to the shaking motor through slip rings which allow the manometer carriage t o he rotated freely. Because the operator need approach the apparatus from one side only, the bath m y he placed in a corner of the laboratory or along a wall between
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V O L U M E 20, N O . 11, N O V E M B E R 1 9 4 8
1101 heater and for the connection between thermoregulator and electronic relay. If i t is desired to gas manometers while they are in the bath, a tube carrying gas to a. gassing manifold may also he brought up through this opening. SHAKING MECHANISM
The conventional rocking type of motion is employed in model I (Figuro 1). A motor (series wound, 1/20 h.p.) with builtin l 5 / l gem reducer and eocentric is mounted on the main supportwith respect to ing a r m (Figu the lower set 'he manomoter
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Figure 3. Shaking Meohanism on Model I SUPPORTING STRUCTURE
I n both types of apparatus the main supporting structure is a cast iron base into which is inserted a 4.5-inch steel pipe. In model I (Figures 1, 3, and 4) the lower half of the steel pipe is machined t o fit two additional castings which support the msr nometer mounts and the shaker arms, respectively. The larger of these two castings is fitted with 18 spokelike steel arms which support the manometers (Figure 3). A plate 0.125 inch thick holding a series of ball bearings provides a low-friction bearing surface for these ratstable parts. The smaller casting is likewise fitted with a steel arm to each of the 18manometer carriage units. I n model I1 (Figures 2 and 5 ) the main casting is machined to fit the two flanged plate supports. Ball hearings are used a t both bearing surfaces. I n addition to supporting the tank, the central pipe serves as a conduit for the wires supplying current to the two motors and
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Lircular Ulatn ana anakmg.Apparatus tor
Micromanometry
supports are fitted to tho carriage arms by machined tongue and groove unions which permit rapid mounting or removal of the manometers. No setscrews me required to hold the manometer
speed of shaking with a rhe'dstat controi:
Figure 6 . Variable Eccentric,
I n thc apparatus shown in Figuro 2 (model 11) the flask contents are agitated by oscillating the flask through a horizontal arc af about 30' on a 10-cm. radius, the center being midway hotwcen the manometer tubes.
Figure 4. Detail ol Model I
The advantage of this type of shaking mechanism is that the movement of the manometers is negligible when the flasks are in
ANALYTICAL CHEMISTRY
1102 is full motion; the slight movement f, the and iLwayfrom the ohserver and the fluid in the manom. eter does not bounce. Thus readings are made easily without decreasing the rate of shaking or stopping the manometers completely, 8.8 is required with the conventinna.1 apparatus.
thc center of the rnain drive shaft. For maximum motion i t is adjusted to make the eccentricities add (Figure 6, B ) , and the center of the outer cylindrical bearing surface LSat a maximum distance from the center,f the drive shaft, A stop screw (Figures 2 and 5 ) serves t o prevent rotation of the manometer carriage from any position desired TANX
,The tank, which in early models was made of copper with rolled edges, is now made of spun aluminum. The outside diameter of the tank is 22 inches, the diameter of the central opening is 4.5 inches, and the depth is 7 inches. The tank is supported on the steel pipe hy a cast collar fitted with setscrews. TEMPERATIURE CONTROL
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, >. , , The temperature of the batn 18 conu-ouea ay a mercury-iuglass thermoregulator and electronic relay with a 500-watt heater. If desired, a second heating element may bo installed to bring the temperature up rapidly after the heater has been turned off avernight. Tho water in the bath is kept in motion either with a 1/60 h.p. stirring motor (Figure 2) or by a circulating pump mounted directly under the tank (Figure 1). Tho ciroular bath permits excellent. t,emnera,ture control. since there are no “dead” corners of noncirculating water. ~
Figure 7.
Manometer Bath with Gassing Manifold
To aahieve this type of motion the manomewr8 are uuunted on brass casting whioh fits a 0.5-inch pin on the lower circular plate (Figure 2). [In earlier models the brass casting was made with a projecting piri which fitted a hole drilled into a. large bolt (Figure 5).] A slotted horizontal arm, which is part of the brass casting, is moved back and forth by an upright pin an the top oircular plate. The latter in turn is driven by a variable eecentrio attached to the built-in gear reducer of the driving motor (1120 h.p. induction motor). The extent of shaking can be widely varied by changing the amplitude of the arc, but the rate of oscillation remains constant. The variable eccentric, shown in Figure 6, consists of a cylindrical bearing surface which drives a crank. The eccentricity of this cylinder is controlled by rotating it on a hole which is offcenter with respect to its periphery. This rotates for adjustment on another cylinder which hrts a 0.5-inch drive shaft hole which is off-cent,er an e ual amount. When minimum motion is desired, the device is s&sted so that the eccentricities cancel (Figure 6, A ) and t.he center of the outer cylindrical hearing surface is over
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GASSING MANIFOLD AND MANOMETER STAND
A convenient rotst.ing manometer rack with gassing manifold is shown in Figure 7. Gas is transmitted through the bearing, which allows complete freedom of rotation. Any number of manometers may be gassed, as those manifold tubes not in use are stoppered hy slipping them over their respective projecting
LITERATURE CITED
(1) Dixon, Malcolm, “Manometric Methods,” hrr I YLn,IId*IIIIIyLd*II Co., 1934. (2) Umbreit, W.. Burris, R., and Stsuffer, J. F.,“Manometric Teehni~uues,”Minneapolis, Burgess Publishing Co., 1945. (3) Warburg, 0..“Uber den Stoffwechsel der Tumoren,” Berlin, Julius Springer, 1926. R e o e i v ~ oMaroh 31,1948. Published with the amroval of the director of the Wiseonsin Agricultural Experiment Ststion. Bunds for the construction of the original circular apparatus were provided by the University Research Committee. This & ~ ~ h r a t ig n abeing made available oommeroially by the American Instrument Co.. Silver S~ring,?dd., and by GME, 4 Franklin Ave., Madison. IVis.
Separation and Microdetermination of Small Amounts of Aluminum THOMAS D. PARKS
AND
LOUIS LYKKEN
Shell Development Company, Emeryville, Calg.
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HE determination of aluminun, in the presence of other . ” metals 1s usually accompanied by the problem of interferences, and is accentuated when the amount of aluminum is small in proportion to the interfering ions. Recent investigators have used ether extrsotion (4) or mercury cathode electrolyses ( I S ) for the separation of interfering metals previous to the estimation of aluminum by the aluminon colorimetric method. Others have used organic precipitating agents such as cupferron (16) for the separation of aluminum from such metals as iron and zirconium. or have determined aluminum by difference in the
large amounts of rtlumina. from the oxides of iron, titanium, and zirconium (16). As demonstrated below, it W&S found that the sodium carbonate fusion procedure is also an efficientmeans for separating very small amounts of aluminum from large amounts of interfering elements, particularly if used in eonjunction with electrolysis a t the mercury cathode ( I S ) . Considerable work was done with the aluminon colorimetric method (4) in order io find the best procedure for determining microgram quantities of aluminum. Although the aluminon method gave reasonably accurate results when the important
