US2604383A

US2604383A - Continuous titration apparatus

Info

Publication number: US2604383A
Application number: US654927A
Authority: US
Inventors: Erwin E Morse
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-03-16
Filing date: 1946-03-16
Publication date: 1952-07-22
Anticipated expiration: 1969-07-22

Description

y 22, 1952 E. E. MORSE 2,604,383

CONTINUOUS TITRATION APPARATUS Filed March 16, I946 INVENTOR. ER W//\/ E. MORSE Patented July 22, 1952 UNITED STATES PATENT OFFICE CONTINUOUS TI'TRATIO'N APPARATUS Erwin E. Morse, wooalanaloauf. Application Marchic, 1946', Serial No. 654,927

'12 Claims. 1 The invention relates to apparatus for performing' continuous titration.

- One" of the most important processes in thefield of chemistry is that of titration.- In thisproce'ss, the concentration of a dissolved substance in solution is deter-tinned by measuring the smallest amount of it required to bring about a given effect in reaction with another solution or substance In performing any titration,the chemist must have some means of deter-miningthe point of equivalence of the two reaoti'ng chemicals. In certain cases where one of the reactants serves as its own indicator, this can be seen by a sudden change in the color of the reacting solutions. In other cases, completionof titration is indicated by a change in the color of a third substance.

since the processof titration isachemic'al one, with associated changes in physico chemi'cal properties of the solution, the variation in the magnitude of these properties can often be used as an indirect indicator oi the completeness of titration. An important type of: indirect indicater which functions by means of achange in a physico-ch'emical property of the solution is the galvanic cell, which produces a small but definite electromotive force, the value of which depends o the chemical state or the solution. The choice" of electrodes for the galvanic cell is determined by the particular titration reaction under con s'ider'atiom In my present'invention I make use of a galvanic cell, activated by the solution under examination, to initiate the operation and control of devices for carrying on continuously and automatically, and recording; a titration process of special usefulness in the manufacture of beet sugar.

it is therefore'a broad object or my inventionto provide. an apparatus and process for perform ing an automatic and continuous titration of an acid solution with an alkaline solution; or of an alkaline solution with an acid solution. It is also an object of my invention in a narrower sense to provide ameans for and i'nethod' of automatically and continuously eontrqmng, m asuring and re cording the alkalinity of the first carbonation fil= trate in the manufacture of beet sugar. I

invention p'os'sesses other va1uab1'e;reatures, some of which" with the foregoing will be set forth at length in the following description where that form of the invention which has been selected for illustration in the drawings accompanying and forming a part of the present speciflcation is explained. In said drawings, one form of the invention is shown. but it is to be understood that it is not limited to that form, since the invention as set forth in the claims may be e'inbodied'in a plurality or forms.

In the drawings, the figure is a diagrammatical view of the entire apparatus of my inventiom While it will be obvious that my inventionmay be adapted and applied in many different manufacturing and production arts, its application in the making of beet sugar will be treated in the following explanation of my invention.-

In the production of sucrose from sugar beets,- one of the most-important steps inthe process is the defecation of diffusion juice with mill; of lime and carbon dioxide. The first part ofthe' defecation process is termed first carbonation." The mixture obtained from the mixing of di'fi u sicnjuice, milk of lime oi sac'charate milk, and carbon dioxide is called first carbonation juice. Probably the most important controlling variable in the first carbonation process is the alkalinity of the filtered juice;

The determination of alkalinity is simply a titration of an alkaline solution with an midsumtion. The filtered first carbonation" juice is the alkaline solution; and 0.0357 normal sulfuric acid filtered juice is taken, the volume of a'cidre quired for neutralization, divided by 100, isthe numerical measure of the alkalinity. Further more, the alkalinity equals the number of grams of calcium oxide per milliliters of juice,.assuming that calcium hydroxide is the only alkaliv present in the juice.

First carbonation control depends primarily uponthe determination of the alkalinity which is made manually by the carbonation operator. Thus the operator takes a sample of firstcarbonation juice from the carbonation tanks, filters the juice and titrates a 10 milliliter sample of the filtrate with 00357 normal sulfuric acid, using 'phenol-phthaleinas a color indicator. If the measured alkalinity. of the juice varies from the desiredfigure. the addition otthe milk of lime or carbon dioxide gas is changed so as to obtain the desired figure.

Approximate alkalinity control is frequently obtained by the use of intermediary devices such as pH or conductivity controllers. The principal objection to these devices is that other factors such as temperature or percentage of lime may alter the relationship between alkalinity and pI-l or alkalinity and conductivity;

Referring to the drawing, a continuous flow of first carbonation jiiice passes through sample line 2, into the filtf pm; 3, then bill; the overflow pipe 4 and back to the process. If the Dorr system of continuous first carbonation is used, it is convenient to connect sample line 2 to the pressure side of the recirculation pump. With other carbonation systems, the sample line should be so installed that the sample is representative of the completely limed and carbonated juice. A filter 6 consisting of a perforated cylindrical frame covered with a filter medium such as 16- ounce duck filter cloth is immersed in the juice, and connected by pipe 1 to a filtrate receiver 8. A filtration area of 25 square inches is usually satisfactory under normal operating conditions.

The filtrate receiver 8 is also connected through the pipes 9 and I0, between which a trap I2 is interposed, and through the three-way reciprocating valve l3, alternately with a pressure tank l4 and a vacuum tank IS. The trap protects the valve from the juice in the vacuum phase of its operation; and provides a convenient place for mounting a gauge H, on which the degree of vacuum and the amount of pressure in the connecting lines may be indicated. The trap is also provided with a drain valve l8 at its lower coned end. v

The vacuum may be conveniently set at 3 inches of mercury for 17 seconds and the pressure at 1 lb. per sq. in. for 7 seconds. The filtered juice collects in the filtrate receiver 8, while the vacuum is being applied to the system and is blown into the supply tank l9 through the connecting pipe 2|, when pressure is applied to the filter. Simultaneously the layer of solid matter which collects on the filter surface during the vacuum part of the filtration cycle is blown off. Admission of air to the filtrate receiver 8 is prevented during the vacuum part of the cycle by the check valve 22, interposed in the pipe 2|.

The supply tank I9 is provided with an overflow pipe 23, to a waste return line; and the tank is advantageously madeof such a size that the retention time of the juice in the tank is short. A volume of 135 milliliters below the overflow level is a satisfactory value for first carbonation juice.

Connected to the bottom of the supply tank l9 bya pipe 24, controlled by a valve 25, are the coils 26 of a heat exchanger 21, to which a cooling medium is supplied through the pipe 28. Again, it is advantageous to construct the heat exchanger so that the minimum volume of .juice commensurate with adequate cooling is' present in the cooling coil at any time. 8 ft. of A" outside diameter copper tubing is satisfactory for first carbonation juice if the cooling medium is water at 20 C.

The filtrate fiows at a steady rate through the valve adjusted passage of the pipe 24, and into the heat exchanger, from which the cooled flltrate flows through the pipe 29 to the constant level tank 3|, provided with an overflow pipe 32 to the waste return line. The tank is mounted for vertical adjustment so that the head of filtrate discharging from the bottom thereof through the flexible conduit 33 may be varied. The discharge conduit 33 terminates in a restricted orifice conveniently provided by a piece of capillary glass tubing 34, in adjustably fixed position and having an internal diameter of .044" and a length of 1".

The constant level tank should be quite small so that the retention time of the juice flowing through it is reduced to a negligible amount. A volume of 20 milliliters or less above the outlet to 4 the discharge tube 33, and below the overflow level, is satisfactory for first carbonation juice.

The flow of cooled, filtered juice to the constant level tank 3| is conveniently set at about milliliters per minute by adjustment of the filtrate throttling valve 25. The juice flows through conduit 33 and is delivered from the restricted orifice of the tube 34, held by any suitable means in a fixed position. The rate of fiow of the liquid is determined by the dimensions of the capillary tip and the static head of the liquid column above this orifice, it being assumed that the temperature of the liquid remains constant. By varying this static head, the rate of flow may be set at any desired value. A convenient rate of flow with first carbonation filtrate is 75.0 milliliters per minute.

In some titrations there may be no need to filter and cool the material to be analyzed. In that case, the sample to be tested will run continuously from the sample line 2, through the pipe 36, indicated in dashed lines, into the constant level tank 3|. If the material is hot or if it has a varying temperature, the sample may be admitted through pipe 31 into pipe 24, above valve 25. The automatic titration may be conducted at any of many different temperatures. The range of 20-25 C. is convenient for most titrations.

Means are provided for supplying a flow of acid solution and mixing it with the flow of juice, automatically controlling the amount of acid by means responsive to the galvanic current generatedby the mixture functioning as an electrolyte in a galvanic couple. A pair of acid tanks 4| and 42 are connected through the three-way valve-43 and pipe 44 to discharge into the con stant level tank 46. Constant level is maintained by means of a glass float valve 4'1. The use of either of two tanks, makes continuous operation possible since acid may be withdrawn from one while the other is replenished.

From the constant level tank 46, the acid flows through the conduit 48 to the inner end of a dispensing tube 49, to which it is flexibly connected, and which is mounted for movement like the hand of a clock on the pivot shaft 5|. The tube is provided with a capillary tip 52 and may have an internal diameter of .044" and be 1.13" long. The acid flows through the dispensing tube by gravity to drop from the capillary tip into an arcuate trough 53, fixed below the capillary tip throughout its range of movement in the lower right quadrant of a circle, concentric with the shaft 5|. It will be clear that the angular position of the dispensing tube 49 determines the head of liquid above the tip 52, and hence if temperature and composition be constant, the rate of fiow from the tip, so that for each angular position of the dispensing tube, there is a corresponding volume flow of acid.

It is desirable to maintain the acid solution at a nearly constant temperature of plus or minus 1 to 2 degrees C. This may be done by immersing cooling coils 54 in the constant level tank 46,

and by circulating cooling water through a jacket 56 surrounding the dispensing tube, and connected by flexible conduits 5'|.with the necessary facilities.

For the titration of first carbonation filtrate, it is preferred to have the distance between the center of the pivot shaft 5| and the capillary tip 52 about 20". The speed of rotary movement of the pivot shaft is of course quite slow; and may be arranged at about .015 R. P. M. by the d oceses use of suitable reduction gearing .58 driven by the reversible synchronous electric motor 9-. The alkaline first carbonation filtrate is .con-

ven'iently added to the acid at the lower end of the acid trough, the adjustably fixeddischarge tube 34 being positioned immediately above the end of. the trough, so that filtrate and acid. pass together through the discharge nipple .61 into the. mixing tube .52, in which mixing. is insured by allowing. the. acid and alkalito flow over about adozen small glass beads .63, which may conveniently be about .12. in diameter.

The. mixture of: acid andalkali is nextpas'sed by or through a detecting element which determines whether equivalent amountsofi acid and alkali arepresent. Any oiia number ofdiiie'rent galvanic cells may begused .tomeasure .the hydrogen ion activity in .the solution. Examples of these cells are the .antimonyecalomel cells and the. glass electrode-,calomel cells. Inasmuch as the hydrogen ion activity (expressed as pH, the log of the reciprocal of hydrogen ion activity) is the most direct and exact measure of the degree of neutralization, it is preferred to. usea galvanic cell composed of a glass electrode and a. saturated calomel electrode as the detecting element.

This detecting element is conveniently placed in a pH pct 64 having the shape shown in the drawing. This is madegof metal to protect the electrodes from mechanical and electrical disturbances. The electrodes are placed in side arms t6 and 6] so that the tips of the electrodes project into the stre m of liquid flowing through the pH pot. The discharge tube 6.8 of the pH pot is so arranged that the level of the solution is maintained about /a" above the upper. or glass electrode bulb; and the internal diameter of the pH pot should be about /2 so as to keep the volume of solution in the pot at a minimum value.

There should be the least possible distance between the bottom of the trough 53 and the glass electrode in side arm 56. Therefore nipple BI and tube .62 should be of minimum length and the glass electrode should always be placed inthe uppermost side arm of the pH pot. .Within 5 seconds after a change in'the flow of acid there should be an indicated change in the pH of the mixture in pH pct 64.

Means are providedfor measuring the F. produced in the cell, and for utilizing this'currenf to control motor means responsive to its variations, to swing thedispensing tube to vary the volume of acid dropping into the trough.

The electrodes of the cell are connected by leads ii and 12 .to an automatic pH indicator 'lfi such as Beckmans model B. This instrument measures the electric: potential produced by the electrodes; and its scale 14 is calibrated in pH values corresponding to such potential, so that the pointer at all times indicates the pH condition in the. pot. The instrument is provided with terminalsby which an additional indicating meter at aremotepointmay be'connected; and I make use of. these terminals to connect, by

means of leads if? and'lil, a highly sensitive'moving coil relay it: This relay makes contact on one side when the current flowing through the coil is reduced and on the other side when the current is increased. Inasmuch as the magnitude of the current depends on the pH of the mixture of the acid and alkali, it is evident that the operation of the'sensitive movingcoil relay depends on thispH value.

The relay .l s in turn controls-two relays .8 i and 3| functions whenrelay 79' makescontact on the low side-19A and relay 32 functions when .relay 19 makes contact, on the high side 19B. Neither relay 8! nor .82 will function when the moving contact of relay i9 is in its intermediate position.

Connected by the leads B5 to the power line 86 for control by the relays 8| and 82 is the reversible synchronous electric motor 5! Limit switches of conventional design, not shown, are provided to control the rotation of. the motor, to keepmovement of the dispensing tube .49 within its permissible range in the quadrant selected for its operation.

The operation of the apparatus as so far. .de-

scribed is as follows: It is assumed that first carbonation juice is flowing through the filter pot 3; that, pressure andvacuum are alternately being supplied to the filter 6; that cooling. water is being supplied to the heat exchanger 2?; and that the static head on the orifice of the discharge tube 34 is adjusted so that the desired flow of first carbonation filtrate is being obtained. Furthermore, it; is assumed that the potentiometer 13 is so adjusted that the moving contact of relay 79 is in its intermediate position when the. pH of the acid-alkali mixture'fiowing through the pH pot 54 has that value corresponding to the presence of chemically equivalent amounts of acid and alkali. For first carbonation filtrate and 0.0357 normal sulfuric acid, it has'been found that this pH value is 7.08 at 25 C. This adjustment of the electronic potentiometer is readily made.

Under these conditions, a stream of cooled first carbonation filtrate will be delivered from the discharge tube 34, at a constant rate and mixed with the acid solution flowing from the restricted orifice or capillary tip 52. If chemically equivalent amounts of alkali and acid are present in the two streams, the mixture will be chemically neutral and have a pH value or" 7.08. The moving contact of the sensitive relay 'll-lwill hence lie in its intermediate position and neither relay 8| nor relay 8? will operate, so that the shaft 5i is at rest. If, however, the mixture ofacid an alkali contains an excess of alkali, the: pH of the mixture will be greater than 7.08 and the moving contact of the relay 19 will make contact on the side 18B; and this in turn willcause relay 82 to close. In turn,.the reversible motor will operate so as to rotate the shaft iii in a clockwise direction. This will increase the static head of the acid column on orifice 52, and hence the flow of the acid solution will increase. When the rate of flow of the acid is such that the mixture of acid and alkali is chemically neutral or the pH is reduced to 7.08, the moving contact of relay 79' will seek the intermediate position, relay 82 will become inoperative and motor 59 will stop. The dispensing tube 49 then remains at rest; and the rate of flow of the acid solution is constant;

Suppose now that the alkalinity of the'iirstmakes contact on the side 19A. This causes relay 8 lt'o function and the motor operates'to rotate shaft- 5l in a counter-clockwise direction. The.

static head of the acid column on orifice 52 1s lessened and consequently the now or acid is reduced. Equilibrium between the acid and alkali is thus again attained, the pH of the mixture equals 7.08 and the dispensing tube 49 again comes to rest. Thus the flow of acid is subject to constant and automatic variation so as to maintain the chemical balance between acid and alkali,

From the above description it will be obvious that my continuous titration apparatus i not necessarily restricted to the use of a constant flow of alkali and a variable flow of acid. The acid flow could be made constant and the alkali flow varied. Similarly, it an acid solution of unknown composition were being analyzed, this solution could be run through the apparatus at a constant rate while varying the flow of a solution of alkali of known strength or the alkali solution could be used at a constant rate of flow, while the rate of flow of the acid solution was varied. In general, if VA and NA are the volume in milliliters per minute and the concentration in equivalents per liter for the acid and VB and NB are the corresponding quantities for the alkali, the condition for equilibrium is that VANA=VBNB. It can be readily seen that if any two of these quantitles are fixed in value, the values of the other two quantities bear a direct relationship to one another. Thus if VB and NA are fixed in value, NB bears a direct relationship to VA. This is the case in which the rate of flow of the alkali and the strength of the acid are held constant. Then the strength of the alkali is directly proportional to the flow of acid. We might also hold VA and NA constant, in which case NB is inversely proportional to VB.

We will assume that the automatic titrimeter is being used as first described, namely with a constant flow of alkali and a variable flow of acid, the alkali being of varying strength and the acid of constant strength. The flow rate of the acid is then a measure of the strength of the alkali.

Means are provided for measuring and recording the flow rate of acid. Such means include a recording potentiometer 9!, a 50-ohm resistance 92, a variable 50-ohm resistance 93, a variable 150-ohm resistance 94, and a 1.5 volt battery 95,

in a circuit as shown in the upper part of the figure. A contact arm 96, fixed for movement with the shaft and dispensing tube 49, ranges over the resistance 93; and a single pole double throw switch 9! permits connection of the potentiometer 9! across the resistance 92 through leads 98 and 99 or across resistance 92 plus that portion of resistance 93 included in the circuit by the contact arm 96. The battery 95 supplies the current and the variable resistance 94 permits adjustment of the current to a value of .007 ampere.

This adjustment is made by throwing switch 91 to the left so that the potential drop between points A and B is measured. Inasmuch as the value of resistance 92 is 50 ohms, the value of resistance 94 may be adjusted so that the observed potential drop is 0.350 volt. When switch 91 is thrown to the right, the potential drop between points A and C is measured.

It is now obvious that for every position of the output shaft 5| there will be a corresponding flow of acid from orifice 52, and a corresp nding position of the contact arm (position 0) on resistance 93. The potential drop across AC is therefore a direct measure of the flow of acid and in turn this is a measure of the alkalinity of the first carbonation Juice. It is thus possible to calibrate the recording potentiometer directly in terms of alkalinity, simply by measuring the flow of acid for several different positions of the acid delivery tube 49. Knowing the strength of the acid and the flow of the first carbonation juice, the alkalinity of the juice is easily calculated.

The values .007 ampere and .35 volt referred to above are not limiting or generally definitive, but merely those actually used in an apparatus embodying my invention, and on which the potentiometer 9| measured a minimum potential drop of .35 volt. With another potentiometer, different values might be necessary for correct operation.

I claim:

1. In titration apparatus, a movable liquid dispensing means movable to vary the static head and thus the amount of liquid discharging therefrom, means including a constant level device for maintaining a continuous supply of the liquid to said dispensing means, a reaction chamber for receiving said liquid, means for introducing in constant volume flow a second liquid into said chamber, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, and means including means responsive to variation in the output current of said cell for moving said dispensing means.

2. In titration apparatus, a chamber for holding liquid, movable means for introducing liquid in a variable volume flow into said chamber, means for introducing in constant volume flow a second liquid into said chamber, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, means including means controlled by the output current of said cell for controlling said movable means to control the volume of liquid introduced thereby into said chamber, an electric circuit, a recording potentiometer in said circuit, a variable resistance in said circuit with said potentiometer, and means connected to and actuated by said movable means for controlling said variable resistance and thus the current flow in said circuit to said potentiometer.

3. In a titration apparatus, a movable liquid dispensing means movable to vary the static head and thus the amount of liquid discharging therefrom, said dispensing means having a restricted outlet means including a constant level device for maintaining a continuous supply of the liquid to said dispensing means, a reaction chamber for receiving said liquid, means for introducing in constant volume flow a second liquid into said chamber, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, a motor operatively connected to the dispensing means to move the same, means including relay-controlled circuits for controlling the motor, and means responsive to the output current of said cell for selectively operating said relays.

4. In a titration apparatus, a movable liquid dispensing means movable to vary the static head and thus the amount of liquid discharging therefrom, means for maintaining a continuous supply of the liquid to said dispensing means, a reaction chamber for receiving said liquid, means for introducing in constant volume flow a second liquid into said chamber, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, means including means responsive to variation in the output current of said cell for moving said dispensing means, a recording potentiometer, a resistance in circuit therewith, and means connected for movement with the liquid dispensing means for varying the resistance. i

5. In a titration apparatus, a pivotally mounted shaft, a movable dispensing tube fixed radially on said shaft for movement therewith to various angular positions, means connected to said tube for supplying a liquid thereto and positioned to give a constant head at the point of said connection, the angular position of said tube regulating the static head of said liquid and thus the rate of flow of said liquid through said tube, a chamber for holding liquid, means for conducting liquid discharging from-the dispensing tube at angularly adjusted positions to the chamber, means for introducingv into said chamber a constant volume flow of a second liquid, a pair of electrodes arranged in the chamber to form with the liquid therein agalvanic cell, a revensible-motor drivably connected to said shaft, normally' open circuits for supplying electrical energy to said motor, means selectively responsive to the output current of said cell for closing one of said circuits to energize the motor to turn the shaft to vary the angular position of said tube, and means for measuring the rate of flow of the liquid passing through said dispensing tube.

6. In a titration apparatus, a pivotally mounted shaft, a movable dispensing tube fixed radially on said shaft for movement therewith to various angular positions, means connected to said tube for supplying a liquid thereto and positioned to give a constant head at the point of said connection, the angular position of said tube regulating the static head of said liquid and thus the rate of flow of said liquid through said tube, a chamber for holding liquid, means for conducting liquid discharging from the dispensing tube at angularly adjusted positions to the chamber, means for introducing into said chamber a constant volume flow of a second liquid, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, a reversible motor drivably connected to said shaft, normally open circuits for supplying electrical energy to said motor, a prime relay for closing each of said circuits, relay means for operating each of said prime relays, means responsive to the output current of said cell for selectively operating the relay means to operate one of the prime relays to close a circuit to energize the motor to turn the shaft to vary the angular position of said tube, and means for measuring the rate of .flow of the liquid passing through said dispensing tube.

'7. In a, titration apparatus, a movable liquid dispensing means movable to vary the static head and thus the amount of liquid discharging therefrom, said dispensing means having a restricted outlet, means for maintaining a supply of the liquid to said dispensing means, a reaction chamber for receiving said liquid, means for introducing in constant volume flow a second liquid into said chamber, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, means including means responsive to variation in the output current of said cell for moving said dispensing means, and means for measuring the rate of flow of the liquid discharging from said dispensing means.

8. In a titration apparatus, a movable liquid dispensing means movable to vary the static head and thus the amount of liquid discharging therefrom, means including a constant level device for supplying the liquid to said dispensing means, a reaction chamber for receiving said liquid, means for introducing in constant volume flow a second liquid into said chamber, means including means associated with said chamber and responsive to changes in the'physico-chemical properties of the solution created by the-mixture of said first and second liquids. for moving said dispensing means, and means for measuring the rate of fiow of the liquid dischargingfrom said dispensing means.

9. In a titration apparatus, a pivotally mounted shaft, means for turning said'shaft, a movable dispensing tube fixed radially onsaid shaft for movement therewith to variousangular positions, means connected to said tube for supplying a liquid thereto and positioned to give a constant head at the point of' said connection, the angular position of said tube regulating :the static head of said liquid and thus the rate of flow of said liquid through said tube, a chamber for holding liquid, means for conducting liquid dischargingfrom the dispensing tube at angue larly adjusted positions to the chamber, means for introducing into said chamber, a constant volumefiowof a second liquid, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, and means responsible to the output current of said cell for actuating said means for turning said shaft to vary the angular position of said tube.

10. In a titration apparatus, a pivotally mounted shaft, a movable dispensing tube fixed radially on said shaft for movement therewith to various angular positions, means connected to said tube for supplying a liquid thereto and positioned to give a constant head at the point of said connection, the angular position of said tube regulating the static head of said liquid and thus the rate of flow of said liquid through said tube, a chamber for holding liquid, means for conducting liquid discharging from the dispensing tube at angularly adjusted positions to the chamber, means for introducing into said chamber a constant volume flow of a second liquid, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, a reversible motor drivably connected to said shaft, normally open circuits for supplying electrical energy to said motor, and means selectively responsive to the output current of said cell for closing one of said circuits to energize the motor to turn the shaft to vary the angular position of said tube.

11. In a titration apparatus, a pivotally mounted shaft, a movable dispensing tube fixed radially on said shaft for movement therewith to various angular positions, means connected to said tube for supplying a liquid thereto and positioned to give a constant head at the point of said connec tion, the angular position of said tube regulating the static head of said liquid and thus the rate of flow of said liquid through said tube, a chamber for holding liquid, means for conducting liquid discharging from the dispensing tube at angularly adjusted positions to the chamber, means for introducing into said chamber a constant volume flow of a second liquid, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, a reversible motor drivably connected to said shaft, normally open circuits for supplying electrical energy to said motor, a prime relay for closing each of said circuits, relay means for operating each of said prime relays, and means responsive to the output current of said cell for selectively operating the relay means to operate one of the prime relays to close a circuit to energize the motor to turn the shaft to vary the angular position of said tube.

12. In a titrating apparatus, a pivotally mounted shaft, means for turning said shaft, a movable dispensing tube fixed radially in said shaft for movement therewith to various angular positions, a constant level reservoir for holding a liquid, a conduit for connecting the reservoir to the dispensing tube at a point removed from its free end, the angular position of said tube regulating the static head of said liquid and thus the rate of flow of said liquid through said tube, a chamber for holding liquid, means for conducting liquid discharging from the dispensing tube at various angular positions to the chamber, means for introducing in constant volume flow a second liquid into said chamber, a pair of electrodes arranged in the chamber to form with the liquid therein a galvanic cell, means controlled by the output current of said cell for actuating said means for turning said shaft to vary the angular position of said dispensing tube, and means for measuring the rate of fiow of the liquid passing through said dispensing tube.

ERWIN E. MORSE.

REFERENCES CITED The following references are of record in the file of this patent:

12 UNITED STATES PATENTS Number Name Date 1,089,030 Angeli Mar. 3, 1914 1,340,649 Crandon May 18, 1920 1,341,790 Edelman June 1, 1920 1,450,023 Edelman Mar. 2'7, 1923 1,530,833 Keeler Mar. 24, 1925 1,643,243 Hatfield Sept. 20, 1927 1,759,996 Parker May 27, 1930 1,830,333 Parker Nov. 3, 1931 1,860,321 Ramsey et a1 May 24, 1932 1,951,035 Parker Mar. 13, 1934 1,956,741 Hornberger May 1, 1934 2,044,164 Gullicksen June 16, 1936 2,308,917 Hardinge Jan. 19, 1943 2,367,949 Langer Jan. 23, 1945 OTHER REFERENCES Hickman et al., Automatic Titrating Devices, Ind. and Eng. Chem, Anal. ed., vol. 5, No. 1, J anuary 15, 1933, pages 65-68.

Claims

1. IN TITRATION APPARATUS, A MOVABLE LIQUID DISPENSING MEANS MOVABLE TO VARY THE STATIC HEAD AND THUS THE AMOUNT OF LIQUID DISCHARGING THEREFROM, MEANS INCLUDING A CONSTANT LEVEL DEVICE FOR MAINTAINING A CONTINUOUS SUPPLY OF THE LIQUID TO SAID DISPENSING MEANS, A REACTION CHAMBER FOR RECEIVING SAID LIQUID, MEANS FOR INTRODUCING IN CONSTANT VOLUME FLOW A SECOND LIQUID INTO SAID ABOUT 20 DAYS TO ABOUT 30 DAYS SO THAT SAID SOLUCHAMBER TO FORM WITH THE LIQUID THEREIN A GALVANIC CELL, AND MEANS INCLUDING MEANS RESPONSIVE TO VARATION IN THE OUTPUT CURRENT OF SAID CELL FOR MOVING SAID DISPENSING MEANS.