US2692820A - Method and means for effecting automatic fractionation - Google Patents

Description

Oct. 26, 1954 c. p. 'ALWAY ET A1. 2,692,820

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 1950 10 Sheets-Sheet 1L IISV-AC RECTIFIER t FILTER UNIT A I59 I CLAYTON D. ALWAY I NORMAN DRAKE WILL/AM a. HA/NES 1 OL/v R R. Wooos 9- t by M 3m entors attorney Oct. 26, 1954 c. D. ALWAY ET AL METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION 1O Sheets-Sheet 2 Filed 001;. 28, 1950 CLAYTON D. AL WAY NORMAN A. DRAKE lnventors W/LL/AM L/ HA/NES OLIVER R Wooos 8g i/ /morneg Oct. 26, 1954 c. D. ALWAY ETAL METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION l0 Sheets-Sheet 3 Filed Oct. 28, 1950 Zinnentors Y 4 E 3/ M M m M 2 bH 3 AJ NN 0AM TM/ V: L M CNW mw (Ittomeg OL/l/EA WOODS Get. 26, 1954 c. D. ALWAY ET AL 2,692,820

METHOD AND MEANS EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 1950 10 SheetsSheet 4.

CLAYTON D4 AL WA Y NORMAN A. DRAKE 7 W/LL/AM H 5 Imventors OLIVER R. I/VOODS Cttomeg Oct. 26, 1954 c. D. ALWAY ET AL METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 1950 10 Sheets-Sheet 5 r CLAYTON D. AL WAY NORMAN A DRAKE WILL/AM J. HA/NES 3nveutors OLIVE/P R Wo'oos Oct. 26; 1954 Filed Oct. 28, 1950 'lmlllll lllll c. D. ALWAY ET AL ,69 METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION 1O Sheets-Sheet 6 -IGB CLAYTON D. ALWAY NORMAN A, DRAKE WILLIAM J. HA/NEs OLIVER R. I/I/ooos Zmvenlors Oct, 26, 1954 c, D ALWAY ET AL 2,692,820

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 1950 10 Sheeis-Sheei 7 CLAYTON D. ALWAY NORMAN A. DRAKE OL/ vER R. Woo0s WILLIAM J HA/NES Zmvenms 1954 c. D. ALWAY ET AL ,6 2,82@

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION I 1O Sheets-Sheet 8 Oct. 26,

Filed Oct. 28. 1950 Oct. 26, 1954 c. D. ALWAY ET AL METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION 10 Sheeis-Sheet 9 Filed Oct. 28, 1950 WAY NORMAN A DRAKE 3nventors CLAYTON D. AL

WILLIAM 0, HAINES OLIVER R Woooa Get. 26, 1954 C. D. ALWAY ET AL 2,692,820

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 1950 10 Sheets-Sheet 10 CONTROL H5v AC fig. 20

501. velvr SELECTOR curruw;

POINT CONTROL CoMPA RATOI? COUN TEE AMPL/ FIE E PELA AMPL/F/ER CLUTCH CONTROL LAMP CHANGE CLAYTON D. ALIA/Av NORMAN A. DRAKE 5 TARTER VOLTAGE OLIVER R" WOODS attorney WILLIAM J H 5 ISnventors Patented Oct. 26, 1954 METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Clayton D. Alway and William J. Haines, Kalamazoo, Oliver R.

Woods, Scotts, and Norman A. Drake, Kalamazoo, Mich., assignors to The Upjohn Company, Kalamazoo, Mich, a corporation of Michigan Application October 28, 1950, Serial No. 192,722

17 Claims.

stantially manually. Thus, the continuous presif ence of a skilled operator for changing the receptacles in which the product is collected, for changing the solvent being introduced into the column, and for filling the proper number of receptacles with any given solvent and/or solute as products of the fractionation has been necessary where such processes have formerly been desired. However, due to the slow action of a fractionating column, an operation involving same often extends over a period of several days during much of which time the operator is frequently idle. Furthermore, unless shifts of operators are provided beyond the normal working hours, the process must be stopped overnight which often introduces further complications.

Accordingly, it becomes apparent that the provision of an entirely automatic instrument which can be pre-set by an operator to effect the above mentioned operation and then be disregarded, would not only relieve the operator for other work, but would also permit continuous operation of the process over extended periods of time. By the equipment hereinafter disclosed, collection of a series of fractions, which would require days by ordinary procedures, may now be accomplished in a few hours.

Accordingly, a primary object of this invention is the provision of an instrument for automatically separating and collecting the respective compounds eluted from a fractionating column.

A further object of this invention is the provision of an instrument, as aforesaid, having means for supporting a plurality of containers for collecting eluted compounds and further means for automatically positioning said containers during the collection of said eluted compounds.

A further object of this invention is the provision of an instrument, as aforesaid, having means for automatically controlling the amount of eluted compounds collected by said individual containers.

A further object of this invention is the provision of an instrument, as aforesaid, having means for introducing in a predetermined sequence a variety of solvents into a fractionating column.

A further object of this invention is the pro vision of an instrument, as aforesaid, having means for controlling the period during which any particular solvent is directed into said fractionating column and, accordingly, the number of containers which are filled with discharge from the column including a particular solvent.

A further object of this invention is the provision of an instrument, as aforesaid, having means insuring a continuous supply of a given solvent to the fractionating column.

A further object of this invention is the provision of an instrument, as aforesaid, which can be operated over a relatively long period of time without constant attention from an operator.

A further object of this invention is the provision of an instrument, as aforesaid, which greatly reduces and greatly simplifies the separation and collection in fractions of compounds eluted from a fractionating column, over methods and means presently available.

Other objects and purposes of this invention will become apparent to persons familiar with this type of operation upon referring to the accompanying drawings and upon reading the following specification.

For illustrations of a preferred embodiment of our invention, attention is directed to the accompanying drawings in which:

Figure 1 is a broken side elevation view of an automatic instrument for detecting, separating and collecting in fractions compounds eluted. from a column, including schematically a portion of the electric circuitry involved.

Figure 2 is a sectional view substantially as taken along the line IIII of Figure 1.

Figure 3 is a sectional view substantially taken along the line III-III of Figure 2.

Figure 4 is a sectional view substantially taken along the line IVIV of Figure 3.

Figure 5 is a sectional view substantially taken along the line VV of Figure 2.

Figure 6 is a sectional view substantially taken along the line VI-VI of Figure 5.

Figure 7 is a sectional view substantially taken along the line VII-VII of Figure 5.

Figure 8 is a sectional view substantially taken along the line VIII-VIII of Figure 5.

Figure 9 is a sectional view substantially as taken along the line IX-IX of Figure 6, and for convenience in showing is rotated approximately 90 degrees in a counterclockwise direction.

Figure is a sectional View taken along the line X-X of Figure 9.

Figure 11 is a sectional view as taken along the line XIXI ofi'F-igure 10;

Figure 12 is a sectional view taken substan tially along the line XII-XII of Figure 1.

Figure 13 is a fragmentary view of a tape and means associated therewith forrecordingmermanently and visually the operation of? the instrument to which this invention relates.

Figure 14 is a sectional view substantially as taken along the line XIV-XIV of Figure. 1.

Figure 15 illustrates diagrammatically a. circuit energizing the fill control lamp.

Figure 16 illustrates diagrammatically the electric circuit responsive to thefilling ofan individual container for effecting moving ofv the next:

successive container into: filling position.

Figure 17 shows diagrammatically a. circuit, adapted for use to. distinguish the differential between the radiation'passing through the sample being tested and through a standard.

Figure 18 represents the counter circuit to gether with the means directly 'connectedthereto.

Figure" 19 represents a suitable power supply circuit.

Figure 20' represents a schematic diagram of the entire mechani'smshowing primarily the relationship between the various portions of the electrical circuit together with their functional association with the mechanical parts.

Figure 21 illustrates therecorderconnections.

GENERAL DESCRIPTION In meeting those objects and purposes here.-

tofore mentioned, as, Well as others incidental.

tionating column and the container being filled.

at a given moment. The difierentiating head is provided with means for determining when the concentration of. eluted material being separated from the fractionating column by a particular solvent rises to, or drops below, a predetermined value. The differentiating head then initiates action to change the solvent. and posi tions another container for collection of further. solvents and eluted compounds dissolved therein. The difierentiating; head in the; specific embodiment here chosen for illustrative purposes comprises a source of electromagnetic radiation of a wavelength absorbable in the compound desired and means responsive to the differential in absorption ofsuch radiation passing (1) through one'transparent cell containing the solvent andv the said compound and (2) through another transparent cell containing only solvent.

However, it will be appreciated as the detailed description progresses that the apparatus and method may also-utilize other types of. radiation.

energy as light of other wavelengths or an electron beam, and. other characteristics than absorptiveness. of the material being sought as its power of optical or magnetic rotation or index of refraction, and these items will be selected according to the characteristics of the material being separated.

An electrical system which effects and controls the operation of the several parts, comprises first, a counting device by which the solvent control valves are changed when a predetermined num ber of containers have been filled with the products of the fractionating column, and secondly, means responsive to control of the differentiating'; head" to. block operation of the counting device so long as said products maintain certain preselected: absorption characteristics. A recorder is' also. provided independently of the valve changingmeans for indicating and recording the amount. of said. eluted material in the column eflluent at any given time. The recording means ishere" shown as visual, but it could also he audible.

Means are also herein provided for urging the solvents from. their respective receptacles. into a. ool'lectingchamher attached to the inlet end of the. fractionating column;. and for maintaining a constant solvent level' in said chamben.

For the purpose of convenience in the detailed description which follows; the terms upper and" lowerj? as used herein will be understood to refer to the instrument It when in its normal operating position; as appearing in" Figure 1. The terms inner or inwardly? and outer or outwardly shall have reference-to the geometric center of the instrument it) or" parts thereof.

The method and device here disclosedmay be usedfor either'partition chromotography or the adsorption chromotography, or for other methods of solvent extraction wherein determination-of the amount of" eluted' material present at a given time in the" discharge from the column may be desiredi CONSTRUCTION Turntable and mechanical portion of its actuatz'ng means upon. and. secured. torthe base plate i l whereby said: turntable: is free to rotate in? a horizontal plane. The purposezof. the turntable H and parts associated therewith. is to move the containers it. supported" thereon successively into position for reception, one at a time, ofv liquid. released. from a fractionat-ingcolumn through a differentiating head it.

Althougha: circular. turntable i I is specifically shown, for illustrative purposes only, the means supporting the containers t2. to be filled with the solution flowing from the fractionating column, it will be readily realized that other conventional, conveyor means, such as a straight line. conveyor, may be used alternatively within the scope of. this. invention.

The turntable H is comprised of a circular topplate or disk ll. (Figures 1. and 2) having anl5 and passing openings 2| being equidistant from the axis thereof. The openings 2! are preferably circular and identical in diameter.

The peripheral edge 22 of the disk I1 is provided with a plurality of equally spaced cams or projections 23 lying within the plane of the disk and extending radially and equidistantly therefrom. The projections 23 are equal in number to the number of openings ER in the disk H and are preferably, but not necessarily,

aligned with said openings along respective radii of the disk.

A micro-switch F2, having a roller contact 73, is supported, as hereinafter described, adjacent to the turntable II so that said contact 13 is in continuous engagement with the peripheral edge 22 of the disk H. The switch 12 is arranged so that it will be normally closed when the roller contact 13 is engaging the edge 22 between any pair of projections 23, and normally open when said contact is engaged by a projection 23.

The turntable H is also provided with intermediate and lower container support rings 24 and 25 respectively, which are spaced downwardly from, and suspended upon, the disk ll by means of the connecting rods 26. The intermediate and lower rings preferably have outside circumferences substantially equal to the cirumference of the disk I! and are coaxial with the pivot post 13. The intermediate ring 24 is provided with a plurality of container openings 2? therethrough, which openings are substantially equivalent in size, radial disposition, and vertical alignment with the container openings 2! in the plate I? (Figure 5). Thus, containers l2, such as test tubes, inserted through the containert openings 2! will also extend through the container openings 2?.

The lower ring 25 is provided with suiiicient horizontal surface and is so disposed to engage and support the lower ends of the containers l2 when they are positioned within the openings 2i and 21. Convenient means, such as the rubber bumpers 28 (Figure 5), may be inserted through appropriate openings of the lower ring 25 for the purpose of cushioning the support of the container l2.

A circular gear 29 (Figures 2, 4 and 5) is secured to the bottom of, and is coaxial with, the support sleeve 18 upon which the disk I"? is mounted. Thus, rotation of the gear 29 effects a rotation of the disk if and the rings 24 and 25 suspended therefrom. The gear 29 is engageable with and rotatable by the worm gear 3i secured upon a horizontal shaft 32 (Figures 2, 3 and 4). The shaft 32 is rotatably supported adjacent to one end thereof upon the vertical end plate 33, which is in turn supported upon the base plate l4 in any convenient, conventional manner. The other end of the shaft 32 is rotatably held in a bearing support 3 5 which is mounted upon a horizontal support plate 35 (Figures 1, 2, 3 and 4) mounted between and upon said end plate 33, another end plate 36 and the pivot post I3. An electric motor 3?, or similar means, is secured upon the base plate l6 beneath the support plate 35 so that its shaft 38 is preferably parallel with and directly below the shaft 32, and extending toward the end plate 33, A stub shaft 39, which is coaxial with; extends toward, and is spaced slightly from, the motor shaft 33, is rotatably supported by means of the bearings 4| mounted within the end plate 33. Both the worm shaft 32 and the stub shaft 39 extend 6 through and beyond the outer side of the end plate 33 for engagement by, and support of, a pair of pulleys 42 and 43, respectively, which are mutually engaged by a chain 44 or similar drive means (Figures 1 and 3).

A clutch 45 (Figures 1, 3 and 5) is mounted upon the motor shaft 33 and the stub shaft 39 between the motor 31 and the end plate 33 to effect intermittent, controlled rotation of the Worm gear 3|.

In this particular embodiment, the clutch 45 (Figures 3 and 4) is comprised of one circular clutch plate 46 mounted upon and rotatable with the motor shaft 38, and another circular clutch 7 plate 4'! is mounted upon the inner side of the end plate 33 around the stub shaft 39. The clutch plates 46 and 4'! are provided with circular clutch bands 48 and 49, respectively, on their opposite faces. A circular clutch member 58, having a pair of parallel faces 5! and 52, is secured upon the stub shaft 39 between the clutch plates 46 and 47 for axial movement between the clutch plates 46 and 47. The faces 5| and 52 are engageable with the clutch bands 48 and 49, respectively. Thus, upon appropriate axial movement of the clutch member 50 toward the clutch plate 36, the clutch face 5| will engage the clutch band 48 in a conventional manner and rotation of the motor shaft 38 will thereby effect rotation of the stub shaft 39. Movement of the clutch element 50 toward the clutch plate M, will cause engagement between the clutch face 52 and the clutch band 49, thereby causing the clutch member 56, if rotating, to stop quickly, also in a conventional manner.

The clutch member 56 (Figure 3) is provided with a relatively deep, annular groove 53 between its two parallel faces 5| and 52. A sleeve 5; encircles the clutch member 59 within the annular groove 53, thereof, and is rotatably mounted upon the clutch member 50 by means of a bearing 55. A yoke 56 (Figures 3 and 4) extends about the sleeve 54 and its arms are pivotally secured to the sleeve 54 by means of the pins 51. The arms of said yoke 55 are rotatably supported at their free ends upon a substantially vertical rod 58 extending therethrough and secured at its opposite ends to the base plate 24 and the support plate 35. Accordingly, movement of the yoke 56 in a horizontal plane will effect axial movement of the clutch member 59 back and forth between the clutch plates 46 and 4?.

A horizontal bar 59 (Figures 1 and 4) is secured to the yoke 56 and extends therefrom for pivotal engagement at its opposite end by the actuating arm El of the solenoid 62 mounted on the base plate M.

A resilient means, such as the spring 63, is connected at one end to the bar 59, adjacent to the actuating arm 6!, and is anchored at its other end upon a post 64 mounted upon the base plate H4. The spring 63, being under tension tends to urge the bar 59 away from the solenoid 52 whereby the yoke 56, acting through the pins 57, urges the face 52 of the clutch member 59 against the clutch band 49 on the clutch plate 4?, thereby preventing rotation of the clutch member 56. Actuation of the solenoid EL urges the bar 58 toward the solenoid, thereby causing the face it of the clutch member 5!! to engage the clutch band 48 on the clutch plate 46, whereupon the motor 3'! may effect a rotation of the stub shaft 39.

During normal operation of the instrument ,manner to a source of power.

aeoagseo:

I; the-motor 31 is in continuous operation and of the solenoid 62- by the micro-switch 12* or by:

other means hereinafter described.

DIFFERENTIATING HEAD The differentiating head l6. (Figures 1, 2 and.

) is supported upon a horizontal cross bar H which issecured tothe tops of a pair of parallel support bars 70 and Ella which are in turn mountedupon the base plate I l adjacent to the turn table II, so that said. head IB- extends over the top-disk. llv of the turntable H. The horizontal cross bar ll extends laterally beyond the support bar 'lfland adjacent to the peripheral edge 22-0f. the topdisk IT for the-support of the microswitch 12 in the manner described hereinabove.

The differentiating head i6, is divided into inner, intermediate and outer compartments i4, 15 and 16, respectively, by reference to thepivot post I3 of the turntable H, with appropriate,

inner and outer partitions 11 and- 18 between the compartments M. and 15 and the compartments l5 and 16, respectively.

A- source of radiant ener y, such as an ultraviolet tube 19 (Figures 5 andv 6), is centrally disposed. within the inner compartment Hi and is electrically connected in any conventional As mentioned above, the type of. radiation may vary within the scope of this invention and may be any type or Wavelength which will be absorbed, or otherwise physically affected, by the compounds being collected. While it is preferred that such absorption be in a substantially lineal relationship to the concentration of said compounds in the eluted solution, other relationships may be usedv where less accuracy is required or upon proper compensation of the electrical circuit responsive to such absorption. However, in this particular embodiment for extracting steroids containing aconjugated diene system, e. g., cortical steroids, ultra-violet light having a wavelength, of 2,537 Angstrom units has been found advantageous. A baflle plate 8| is supported from the top82 of the differentiating head It for preventing said ultra-violet radiation of the tube 19 from escaping through a vent opening 83. in the top 82. A light opening 84 is provided in the partition. ll adjacent to the tube 19 through which the radiation emanating therefrom may pass into the intermediate compartment 15.

A filter 85 (Figures 5 and 6) is disposed within the intermediate compartment 15 adjacent to the light opening 84 in the partition H for the purpose of controlling the wavelength of the radiation passing into the intermediate compartment 15. However, where the rotary power of the eluted material is being utilized, this filter may be replaced by any suitable means, as a Nicol prism, for polarizing the light from source I 8' into a selected plane.

A pair of absorption cells 86 and 81, which are preferably mirror images of each other (Figures 5, 6, 9, 10, 11 and 14), are disposed within the intermediate compartment 15 adjacent to each other and so that radiation emanating from the tube '19 and passing through the light opening 8:3 will be intercepted by both of said cells. Inasmuch as the cells 86 and 87 are in this embodiment substantially identical, only the cell 85, through which the solvent and compounds dissolved therein pass, will be described with the understanding that such de- 8:1 scription applies in substance to the cell" 81 through which the solvent only passes.

As shown in Figures 6, 9, 10 and, 1.1, the absorption cell 86 is comprised of a, block shaped body member 88, having a substantially cylindrical light passage 89- passing horizontally therethrough. The light passage 89 is provided with cylindrical portions of enlarged diameter at the opposite ends thereof which are internally threaded for reception of a pair of, externally threaded light gathering elements 91 and: 92'.

Filters 93 are disposed in the passage 89" (Figure 11) between the elements 9! and 92" and the body member 88 so that they provide an absorption chamber 94 within the bodymember 8 8.

A fluid inlet canal 85, which opens through the upper surface (Figure 9) of the bodymember 88, extends through said body member and communicates With the absorption chamber 94' near the bottom thereof. A fluid outlet canal 95, which opens through the bottom surface of the body member 88, communicates with the absorption chamber fi l near the top thereof,.. A vent canal 9i communicates between the top" surface of the body member 88- and' the outlet canal 96. The inlet canal 95, where it opens through the top of the body member 88, is provided with an enlarged portion properly beveledfor reception of a transfer tube 98' (Figures 9 and 14') from the fractionating column l5. The transfer tube 98 may be held in snug contact. with the walls of the opening of the inlet canal 95 by any convenient means, such as the clamping device 99 (Figures 6 and 9) secured tothe body member 88. Accordingly, solvent and any materials dissolved therein flowing from the fractionating column [5 through the transfer tube- 98 enter the bottom on the absorption chamber 9 8 through the inlet canal 95 and are carried off therefrom through the outlet canal 96. Therefore, in addition to the fact that the absorption cell 86 must be positioned to permit light from the tube 19 to pass through the light gathering elements 9i and 92 and the absorption chamber 9i thereof, said cells must also be disposed so that the lower end Hit of the outlet canal 95 is disposed directly over the center of the path of the containers 52 mounted on theturntable H. The axes of the light passages 89 through the cells 86 and 8! are disposed at anangle which converges at a point substantially at the center of the tube i9, whereby radiation from' the tube l9 will pass through the absorption chamber 915 of both cells.

The outer partition 18 is provided with a pair of spaced, light openings H32 and H33 (Figures 5, 6 and '7), which are intercepted; respectively,

by said axes of the light passages through the absorption cells 86 and 8'2; Thus, radiation from the tube 19 passes through the light opening 86', the filter 85, the absorption chambers 941 of the absorption cells 86' and 81; and the light openings Hi2 and I03, respectively, in the outer partition 78. A pair of cellssensitive to the radiant energy beam from the source 19, as photo-electric tubes Hi l and H15, are disposed within the outer compartment '56 of the differentiating head H5 so that said radiation passing through the light openings Hi2 and lll3:will strike the filaments of the photo-electric tubes IM and 15, respectively.

Where, the rotatory power of the material is being utilized, suitable devices, such as a pair of Nicol prisms, may be inserted. in the retain:- ing devices H t and H2 (Figure 6) in place of 11 ceptacle MI is not essential but has been found convenient. 7,

Each receptacle I4I (Figure 1) is provided with a hollow stopper I44 through which an outlet pipe I45 extends downwardly adjacent to, but spaced slightly from, the bottom of the receptacle MI. The outlet pipe I45 communicates directly with the manifold chamber I32 (Figure 1) near the upper end thereof. An inlet pipe I46 communicates with the chamber in the hollow stopper I44, which chamber communicates in turn with the inside of the receptacle MI. The purpose of this arrangement is to force a gas through the inlet pipe I46 into the receptacle I lI, whereby the solvent within said receptacle is urged up through the outlet pipe I65 and into the manifold chamber I32.

A by-pass pipe I41 (Figure 1) communicates between the upper end of the manifold chamber I32 and the upper end of the solvent control chamber I3I (Figure 12).

A gas under pressure, from means not shown, is fed into the by-pass pipe I41 through the supply pipe !48. A pressure regulating valve I49 is provided in the supply pipe I48.

Each receptacle MI is provided with a pair of electrically actuated, regulating valves II and I52 (Figures '1 and with a connecting pipe I53 therebetween. The inlet pipe I46, which communicates with the hollow chamber in the stopper hi l, also communicates with the connecting pipe I53. A pressure pipe I54 communicates between the regulating valve I5I and the junction of the supply pipe Hill with the by-pass pipe I41. Thus, the gas flowing through the pipe I48 at a pressure regulated by the valve I ls, flows into the solvent control chamber I3-I, the manifold chamber I32 and the regulating valve I5I. An auxiliary supply pipe I55 connected to the auxiliary supply of gas under pressure, not shown, communicates with the regulator valve I52.

The range of the pressure regulating valve M9 is preferably variable from zero to ten psi. The pressure of the gas supplied through the auxiliary supply pipe I55 is preferably approximately two p. s. i. in excess of the pressure of the gas in the supply pipe I55. The regulator valves I5I and I52 are arranged so that one will be closed when the other is open. Thus, when the valve I5I is closed, as shown in Figure 1, the

pressure in the inlet pipe I56 will be about two p. s. i. in excess of the pressure in the outlet pipe I45, thereby causing the said solvent toflow under pressure through the outlet pipe I and into the manifold chamber I32. When the positions of the regulator valves I5I and I52 are electrically reversed, the auxiliary gas pressure is shut-off and the pressure in the pipes I45 and I46 will become equal, permitting gravity to draw the liquid in the outlet pipe I45 back into the receptacle MI. The electric circuitry involved in reversing the regulator valves I5I and I52 upon energization of the energizing filter I39, will be dealt with in detail hereinafter.

Briefly, each pair of regulator valves I5I and I52 (Figure 20) is provided with a solenoid I58 (Figure 1) which is energized upon closing of the circuit thereof by the rectifier solenoid I56. Energization of the valve solenoid I58 (Figure 1) effects an electrical closing of the valve I5I and opening of valve I52, which causes solvent to flow from the receptacle I4I into the manifold I32. When this circuit including solenoid I58 is opened by de-energization of the solenoid 12 I56, the valve I52 is electrically closed and valve 'I5I is electrically opened. The solenoids I580; through I58d (Figure l) are provided for use with additional pairs of regulating valves (Figure 20) which operate in identically the same man her with appropriate solvent receptacles. The plug I59 is connected to a suitable electrical device, discussed hereinafter, for closing the circuit containing that one of the solenoids I56 through I 58d controlling the fiow of the desired solvent according to a predetermined pattern.

RECORDER Referring to Figure 13, it will be seen that the instrument It is provided with recorder I63 comprising a pair of pens I64 and I65 and a recording tape I66 upon which a visual record is made of the percentage of absorption or transmission of ultra-violet radiation from the tube ls by the solvent and compounds dissolved therein passing through the absorption cell 85. The radiation from the tube I9 is of such wave-length that it will be absorbed by the compounds dissolved in the solvent. Thus, the amount of radiation passing through the cell 55 is visually compared to the amount of radiation from the tube "I5 passing through the absorption cell 8?, through which cell the plain solvent is passing.

A minimum condition of absorption represented by the dotted line I61, is established below which the amount of compound in the solvent being collected by the containers and indicated by said absorption becomes too small for useful purposes. Obviously, this minimum can vary as ;desired or required. The indices I58 along the curve I69 (Figure 13) made by the pen I64 represent points at which the filling of a new container I2 commences. It will be noted that such indices always point toward the line I67 and, therefore, extend leftwardly of the curve I69 when the curve is on the rightward side of the line I67, and extend rightwardly when the curve I69 is on the leftward side of the line I51. When the indices are pointing leftwardly, the containers are being filled with useful compounds. When the indices are pointing rightwardly, a predetermined number of containers are bein filled with non-useful liquid. If the pen I64 does not move to the right side of the line I61 by the time this number of bottles is filled, the solvent is automatically changed. The instrument III can be set by electrical means, hereinafter described in detail, so that a specific, preselected number of containers I2 will be filled with any particular solvent after the amount of compounds dissolved in the solvent and being collected in the containers drops below the minimum line I61. In general, this preselected delay in changing solvents insures satisfactory dissolving of the materials in the fraction chamber by the particular solvent if any is capable of occurring, and it also provides ample time for secondary dissolving to take place, before a solvent is changed. After the solvent is changed, the device provides sufiicient time for proper dissolving to occur between the new solvent and the compounds in the fraction chamber I35, whereby the pen I64 will move to the rightward side of the line I6'I. As shown in Figure 13, the instrument II) in this embodiment is preselected to fill three containers after the curve I69 has dropped below the mini" mum line I61. Thus, as long as .the curve I59 remains to the left of the line I67, the solvent being fed into the fractionating column I5 will be changed after three containers I2 are filled The line;III1.(Eigurel3) made onthe tape. I66.

bycthepen. IE5. recordsl by the indices I'I2 points at which. the solvent. being. fed. into. the. fractionating column; I5 .is changed. Asshown in Figure 20, two..or.more. solvents inlseparate receptacles I II arenormally usedin carrying out.

anioperationof the instrument IIL.

MECHANICAL OPERATION The turntablel I is provided with a plurality of containers I2, and. as many solvents as are required tocarryout a particular operation are;

placed in receptacles I4I, mounted upon the platformv I42 and. connected, as by the outlet pipes: I45l:(Fig.ures 1. and 20), to the manifold chamber I 32: at the top of the fractionating column I5. The inletpipe MA on; the: receptacle. IIII is connected toa pair oflregulatingvalves I5.I and I52. The electrical circuitry, hereinafter described, of the instrument:I;.isturned on and the first solventwill commence collecting. fractions dissolvable there.- into; A-gas under pressure is fedinto the re.- ceptacle: IIII; (Figure. 1) through the-supply pipe I55,.the:valve I52.and.the inlet pipe. lfiilithereby,

urging the solvent. in the receptacle to how. through the. manifold I32. This solventin. the manifoldchamber I32 passesdown. through the. connectioni pipei I35, into. the solvent control chamber" I 3.I. andthentdown through the fraction chamber. I39, in which certain compounds are held; The. auxiliary pressure will continue to force the solvent into the manifold. chamber I3i2runtillthe1floatvl33has been raised to a level wherezthe stem. I34thereof extends between the fieldtwindings I36, I31 and. I38. The rod. I28 (Eiguretl2), actingv asv'a. core, induces a current flow. through. the solenoid F56 which results in.

energization of the solenoid whereby the valve I52lis closedand the-valve I5I is opened. Since thepressureof. the gas in the pipes I45 and I43 isneutraliz'ed by this change of valves, the solvent will stop flowing into the manifold I32. However, as soon as theiioat I33 drops down, the solenoid: I58 will be deenergized and the valvesJEI and IE2 will be reversed, thereby permitting the gas passing through the auxiliary supplypipe! 55, which has a higher pressure than the gas passing through the valve I 43, to urge the solvent out of the receptacle MI.

The solvent in the manifold chamber I32, the connection pipe I35 and the solvent control chamber I3I (Figures 1, 5, 12 and 14), will slowly pass through the fractionating chamber I30 while taking into solution those compounds dis solvable therein. The solvent and solute will then passthrough the transfer tube 98 into the absorption cell 86 and thence into a container held in: the'turntable II directly under the outlet I III inthe cell 86. pass through the absorption cell 86, the solute therein will absorb portions of the radiation from the tube "I9: At the same time, solvent passes fromthemanifold chamber I32- through the bypass tube lflflidirectly into the absorption cell 81' through which the radiation from the tube I9 also passes. Accordingly, the radiation striking thephoto-electric tube I05 will be a function solely of the absorption of the solvent, whereas the? radiation from thetube I9:passing through the absorption. cell 86 and striking the photoelectricltubew lfllluwillhbe a function of both the I45. from each stopper.

As the solvent and solute shown by the dotted line IBI' in FigurelS, the

solvent being fed from a receptacle I II to the manifoldchamber I32 will'remain the same. As each container I2 is filled to a predetermined level with such solute and solvent, radiation from the lamp I15 will be intercepted by the liquid in the container I2 and diffracte-dthereby through the slot I24 onto the filament of the photo-tube I 22. By means of switch circuitry, described hereinafter, the tube I22 will then initiate energization of the solenoid 62 (Figures 1 and 4) whereby the clutch 45willengage the motor 31,. thereby causing the. turntable II to rotate until the contact I3 of .the switch I2 engages a projection 23 on the edge 22of the top disk II, whereupon the turntable is stopped abruptlyby the braking function of the clutch 45.

The energization of the solenoid by the tube I22 is of onlysufficient duration, to effect such rotation of the turntable that the contact I3, will become disengaged from a projection 23, Where it will be whenever the turntable III is not rotating, Immediately thereafter, the switch I2 takes over and continues the energization of the solenoid 62" until the contact I3 again engages a projection 23. Upon deenergization of the solenoid 62, the spring 63'causes the clutch member 50 to engage the clutch plate ll, whereby the rotation of the turntable II is immediately arrested.

Such rotation of the turntable will place the next adjacent container into position for filling. This sequence of operations continues as long as the absorption of radiation from the tube I9 by thefiuid passing through the absorption cell 86 remains above a predetermined or preselected minimum.

As soon as the absorption drops below said predetermined minimum, the counter IfiI (Figure zil) goesinto operation to automatically count a preselected-number of containers to be filled by the solvent and solute, even though the absorption is below said minimum, after which said counter then initiates a change in the solvent being fed into the manifold chamber I32. The counter ISI is automatically reset and commences counting the preselected number of containers as they are filled with the new solvent. andsuch solute as may be removed by the new solvent from the fraction chamber I33. If the amount of solute, or compounds dissolved by the next solvent do not absorb radiation from the lamp I9 above said" minimum before the preselected number of' containers is filled with this newsolvent,,as indicated in the central portion of Figure 13, the counter I JI will initiate a change to a third solvent. After such changing of. solvents, the counter automatically resets itself and commences to count containers containing the third solvent. However, if this particular solvent dissolves sufiicient compounds from the fractionating chamber I30 to absorb radiation from the tube I9 above said minimum, the counter will then permit filling of containers I2 with this solvent and solute indefinitely until,

As long as the absorption by such. solute remains above the minimum graphically ELECTRICAL SYSTEM Although a large portion of the circuits herein utilized are conventional, sufficient of them have been particularly adapted to the mechanical parts herein disclosed and for the specific purposes herein contemplated, that it is deemed desirable to describe said circuits in detail in the interest of presenting a complete disclosure. It should be understood, however, that these items of circuitry are herein described for illustrative purposes only and they may in many instances be substituted or completely replaced by other conventional circuits, providing only that the particular functions and purposes herein described are preserved.

FILL CONTROL LAMP CIRCUIT The fill control lamp II may be of any conventional type. it is preferred that said lamp have a pair of flaments, one of which is normally energized and the second of which becomes energized only upon the failure of the first. Figure illustrates a suitable circuit.

In this circuit (Figure 15) the source I energizes the primary transformer windings 202 and 263 which in turn energize the secondary transformer windings 2M and 255, respectively. The secondary windings are connected in series with the main filament 206 of the fill control lamp H5 and with the variable resistor 2Ill. Thus, in normal operation the filament 206 will be energized by current induced in said secondaries and passing through the filament and through the variable resistor During such normal operation the winding of the relay 258, which is connected in parallel with the variable resistance 253i, is likewise energized and holds the relay contacts 259 open against the action of a spring 2I2 normally tending to close said contacts.

The auxiliary filament 2H1 of the lamp H5 is connected in series with the secondary winding 2% and the contacts 209. The pilot lamp 2 is connected at any convenient point in this circuit. Here it is in parallel with the auxiliary filament 2 I 8' and, therefore, also in series with the contacts 259. Thus, when the main filament 206 burns out, the circuit including the relay winding 2Il8 is broken and the contacts 209 close. Accordingly, the secondary winding 204 energizes the auxiliary filament 2IIl and simultaneously energizes the pilot lamp 2, which warns the operator that the main filament 255 has burned out, that the machine is operating upon the auxiliary filament 2H] and that, therefore, the fill control lamp H5 should be replaced. By placing the pilot lamp 2H in parallel with the auxiliary filament ZII], the said pilot lamp will be illuminated upon opening of the relay contacts 209 regardless of whether or not the filament m is illuminated. Thus, a warning is provided even though the auxiliary filament 2H] has also become damaged and fails to operate.

FILL CONTROL CIRCUIT The fill control circuit (Figure 16) operates upon the energization of the photo-tube I22 by the fill control lamp I I5 and effects initial movement of the turntable II each time a given container is filled to a predetermined level. A portion of the circuit may be arranged to respond only to pulses from the photo-tube I22 having the frequency provided by the light chopper I2'I However, for purposes of safety L,

(Figure 20) in order to insure that the turntable II will move only in response to light emanating from the lamp II5 and not to stray light from the outside sources. Obviously, this portion of the circuit may be removed where no light chopper is used, but it is here shown in the interest of completeness. Further, this circuit is provided with time delay means in order that the movement of the turntable will be initiated only when the container is actually filled to the proper level and will not be initiated by splashing or by drops of solution passing through the light beam.

Referring now to Figure 16, the photo-tube I22 is connected through a shielded cable 223 to the amplifier circuit indicated generally at 224, which circuit may be conventional. In this particular instance, however, the pulses from the phototube I22 flow through the load resistor 222 and the resultant voltage differential is applied through the capacitor 225 of the grid 2250f the amplifier tube 22I, which amplifier tube is conveniently of the 6AT type. The amplifier tube 22? is arranged to operate on the lower portion of its characteristic curve so that its output is sharply limited. That is, the A. C.-voltage at the anode 22I thereof cannot rise above approximately one volt regardless of the voltage on the grid 225. The output at the anode 22I of ampliiier 2.2T is coupled through the capacitor 228 and the resistor 225 to the grid 235 of the amplifier tube 23!, which amplifier is conveniently of the SAUG-type. Other suitable conductors connect the resistor 222 in a conventional manner through other resistors to the cathodes of the respective amplifier tubes 222i and 23 I, and to the shield grids of the amplifier 23L The output of the amplifier tube 23I is conductedto a parallel resonant circuit 239 composed or" the capacitors 24? and 2M and the reluctance M2, which elements are arranged to tune said resonant circuit 235 to the frequency of the light chopper I22? which, in this instance, is 540 cycles per second. Thus, unless the voltage applied to the grid 225 of the amplifier 227 has a frequency of 540 cycles per second, or some simple fraction thereof, very little voltage is developed across the parallel resonant circuit 239.

The output of the amplifier tube 23I is also coupled through the capacitor 2:35 to a suitable rectifier which in this instance is provided by the diode plates 2M and 2&5 in the tube 221. The rectified voltage is then filtered by the resistor 24% and the capacitor 25? and fed through resistor 2&8 to the grid of the thyratron 259.

The anode of the thyratron 2&9 is connected through the resistance 2% to one side of each of the three capacitors 25 I, 252, and 25s, the other side of each of said three capacitors being connected to ground. The side of said capacitor to which the resistance 25% is connected is also connected in series with resistances 25d and 255, which are in turn connected to the conductor 256. Said conductor 25% is connected through the resistance 25l to that side of the parallel resonant circuit 238 opposite from that side to. which the anode of the amplifier 23I is connected.

The thyratron 250 has its grid connected intermediate the resistances 254 and 255, and its cathode is connected to the conductor 255. A relay Zlii has one end of its winding connected to the anode of the thyratron 255 and the other end of its winding connected through the secondary winding of a transformer 252 to the cathode of the thyratron 255. The primary winding of said transformer 262 is energized from any convenient source, such as the secondary winding 269 of the transformer 263. Said transformer 263 also energizes the heaters of the two thyratrons and of the two amplifier tubes in a conventional manner. The capacitor 264 bridges the winding of the relay 26L The contacts 265 are controlled by the winding of the relay 251 and, when closed, complete a circuit through the conductors 266 and 261 which are connected to the poles 416a and 4 I 1a of the connecting plug IA. A power plug 210 is connected to the primary winding 21! of the transformer 263 and provides power for the operation of this portion of the circuit. The micro-- switch 12 is connected across the poles 54B and All of plug 2 in parallel with the turntable starting circuit 408 (Figure 18). The solenoid G2 is connected to the poles M6 and 54! of plug 2.

If an empty container I2 is in the fill position, so that the photocell i222 is not energized, no voltage is applied to the grid of the thyratron 249. Thus, the thyratron 249 will conduct at a sumciently low anode potential as to effect a substantially continuous conduction and the capacitors 252 and 253 are thus kept continually discharged therethrough. Under these circumstances current flows through the resistance 255 from the source provided by the transformer 263. In fill position, one of the cams 23 will hold the micro-switch 12 open so that the solenoid B2 is not energized until the turntable starting circuit S again provides a connection between terminals M5 and All of plug 2. The voltage drop across said resistance 255 is applied through the resistance 215 to the grid of the thyratron 260. This negative bias prevents the thyratron 260 from conducting in response to the potential supplied by the transformer 262 and thus the winding of relay 2B! is de-energized and the contacts 265 remain open. This, by reason of subsequent circuitry, results in the turntable l remaining motionless.

However, when the container in fill position is filled, the photo-tube becomes energized, and a negative potential appears on the grid of the thyratron 249 and prevents it from conducting.

This first allows the capacitors 25!, 252 and 253 to charge in reponse to the potential provided by the source 253. However, as these capacitors become charged, the voltage drop across the resistor 255 becomes so small that the negative bias on the grid of the thyratron 265 is diminished sufficiently to permit said thyratron 269 to conduct. The capacitors 25L 252 and 253 provide sufficient delay between energization of the photo-tube I22 and conduction of the thyratron 269 that the turntable starting circuit 456 will respond only to a filled container and not to splashing or to drops of solution falling from the fractionating column 55. Conduction by thyratron 2% energizes the relay 26! thereby closing the contacts 265 thereof. The capacitor 264 is provided to prevent the relay 26! from. chattering.

Closure of the contacts 255 operates through subsequent circuitry to efiect movement of the turntable l I in a manner described in detail elsewhere herein.

COMPARATOR CIRCUIT The comparator circuit (Figure 17), which is essentially responsive to the differential in output between the two photo-tubes I84 and H15, opens or closes a relay whereby a connection is made which actuates a portion of the herein aiter described counting and control circuit. Said differential in photo-tube output varies according to the concentration of a selected solute in a given solvent flowing at a given time from the fractionating column l5, as described hereinabove. The comparator circuit also provides a small output potential which is connected to the recorder I (it (Figure 20) for recording the operation of the comparator circuit.

The comparator circuit includes a pair of amplifier circuits [H8 and El i, one connected to each of the photo-tubes iii-i and m5, which phototubes may be of any conventional t, pe capable of producing an electrical response corresponding to change in light intensity falling thereon. Each of said photo-tubes is connected through its respective amplifier circuit to said comparator circuit, which latter opens and closes a control relay.

Now considering the comparator circuit (Figure 1?) in more detail, the power source 58!} is connected through the conductors till, the resistor 695, the conductor 68! and the resistor till to the junction 683. The voltage regulator tube 882 and said resistors 69!! and 69! assure a constant voltage being maintained at said junction point. From said junction point 683, one portion of the current travels through the resistor 6G2 to ground. The capacitor 663 bridges said resistor and functions to isolate two photo-tube circuits. Another portion of said current travels through resistor Gill and the shielded cable 568 to and through the photo-electric tube M5 to ground. The final portion travels through the resistor 605 and the shielded cable GM to and through the photo-electric tube Hi l to ground. Variations in light falling upon the photo-electric tubes will vary their respective conductivity characteristics and hence vary the potentials at the junction points 685 and 686. Conductors 697 and t le connect said junction points 685 and 6%, respectively, through the capacitors 608 and 595 to the control grids of the amplifier tubes 5% and 599, also respectively. Said amplifier tubes are each the first of the series of such tubes in the amplifier circuits 6!! and EH], respectively, which circuits are conventional and are hence indicated only schematically. i

The anode output from the tubes 599a and .2931; in each of said amplifier circuits 6H] and 6i i, respectively, is conducted by the conductors 512 and 613, respectively, to the primary windings of a pair of transformers 6M and (H5. One end of each of the secondary windings of said transformer GM is connected through the. conductor 6!! and a high resistance 618, of the order of thousand ohms, to ground through the conductors BIB, 629, 62! and 522. The cathode of the rectifier 616 is also connected to ground. conveniently through the conductor 622. A capacitor 623 may also advantageously be provided to smooth fluctuations in the output of the rectifier SIB. The tap 524 is adjustable with respect to the resistor 6 l 8 and connects same through the conductor 625 to the cathode of the thyratron 526, The anode of the thyratron 628 is connected through the protective resistance 62? to one end of the winding of the relay 628, to which the capacitor 629 is connected in parallel, and the other end of said winding is connected to one end of the secondary winding of the transformer $38. The primary winding of the transformer 93?! is connected to a 6.3 volt power source described in more detail elsewhere herein. The other end of the secondary winding of the transformer 689 is connected to the cathode of said thyratron 625.

The grid of the thyratron 626 is connected through a resistor 63l to one side of the small, biasing battery 632 which battery provides on the order of 1.5 volts. The other side of said battery 632 is connected through the conductor 633 to a point between a pair of relatively large resistors B34 and 835, which in a preferred embodiment of this invention are of the order of 56 thousand ohms. The other end of the resistor 634 is connected through the conductor 63% and E54, and through a smaller, such as a thousand ohm, resistor 631 to the junction point 938. The other end of the resistor 635 is also connected to the junction point 638, which junction point is then connected through the conductors 639, i350 and 644 to the end 640 of the secondary winding of the transformer M5. The contacts 64! and 642 of the relay 643 are connected, respectively, to the conductor 636 and to the junction point 638. The armature 645 of the relay 643 is connected through conductor 6% to the conductor 633.

Referring again to the transformer 515, the end 640 of its secondary winding is connected through the conductor 644 and 660 and the capacitor 661 to ground through the conductors 662, 62! and 622. The conductor S54 is also connected to ground through a high resistance 663, such as 100 thousand ohms.

The winding of the relay 643 has a capacitor 641 connected in parallel therewith and a resistor 648 in series with said winding and capacitor 6 2?. The conductor between said resistor i348 and said capacitor 641 is connected to a 150 volts D. C. source, and the conductor between said winding and the capacitor 641 is connected by the conductor 6A9 to the contact 65d of the relay 623. The armature 65! of the relay 628 is connected through the resistance 652 to ground, thereby to complete the circuit for the winding of the relay 643. The capacitor 653 and the resistor 65? are provided to prevent arcing of the contacts 65! and 650.

The contact 664 of the relay 643 is connected on its respective two sides to the contacts 565 and 666, which co-act with the contacts 430 and 433 appearing on plug 3 in Figure 18. The contact 664 opens and closes the circuit between the connections 430 and MM. which function to operate the circuitry shown in Figure 18 and described in more detail hereinafter.

With the photo-tube 1M exposed to radiation from the lamp 19 passing through the solvent only, the output of the transformer EH5 is comparatively steady. This output passes through the thyratron 626, when said thyratron is conducting, and energizes the winding of the relay 628 by which to hold the contact 650 closed. This energizes the winding of the relay 643 and holds the contact 654 closed, as well as holding the armature 645 against the contacts 64L Since only solvent passes through the cell 81, no radiation passing therethrough from lamp 19 will be absorbed thereby before falling upon photo-tube Hi5. Thus, the output of transformer 614 will be comparatively constant.

Assuming now that the solution discharged from the fractionating column [5 has insufiicient solute dissolved therein to absorb radiation from the lamps 19, said radiation will fall upon the photo-tube Hit and the output voltage of the transformer 665 will equal the output voltage of the transformer M4. The adjustability of the point of contact between the conductor 624 and the resistor 618 provides the means for calibrating the system correctly'to this balanced condition. With the relay 628 actuated and the contact etc closed, the relay 643 is actuated and the armature 645 is connected to the contacts 6M. Since current from the secondary winding of the transformer 6H5 passes through the conductors 644, 660 and 639, the resistance 63! and resistance 663 to ground, when the relay 643 is positioned as shown in Figure 17, a potential is taken from the junction point 638 through the contacts 642, the conductor 646 and the conductor $33 to the control grid of the thyratron 626. In the energized position of the relay 663 a potential is taken from the junction point Sit in the conductor 654 and carried through the contact 6M and the conductors 646 and 633 to the grid of said thyraton 626.

Thus, when there is no absorption of radiation from lamp 79 by the solution discharged from the fractionating column there will be a potential applied to the conductor 644 of the same value as that supplied to the conductor 6H. This is conducted, as above described, to the grid of the thyratron 626 and, together with the biasing potential of the battery B32, acts to block the thyratron. So long as the thyratron is blocked, the relay 628 remains open as shown and the relay 653, as appearing in Figure 17, is not energized. Thus, the connections between the terminals i565 and 666 is open at the contacts 664 of relay 643.

However, as absorption of radiation from lamp '59 increases, the output of the photo-tube 1M decreases, and the potential on the control grid of the thyratron 626 will also decrease. When this grid potential decreases sufficiently to'permit the thyratron to fire, the relay 628 becomes energized and through the closing of the contact {$59 the relay 643 is also energized. This closes the contact 664 and provides a connection between the terminals G65 and 666. Simultaneously this connects the armature 645 to the contact 5M and thereby connects the grid of said thyratron 626 to the conductor 644 through the resistor 631, instead of directly as before. Thus, since the potential in this instance applied to the grid of said thyratron 626 is taken after the occurrence of the drop through the resistance 631, this grid potential of said thyratron immediately becomes still more negative. Accordingly, in order to cause the thyratron again to conduct, the potential in the conductor 644 must become somewhat more positive than would have been necessary had a direct connection between said grid and said junction point 6588 been maintained. The purpose of this is to insure that the concentration of solute in the product of the fractionating column has actually changed a material amount before the system is caused to respond thereto, and to prevent response of the system to the minor changes in said concentration which are always present and which, if not damped out, cause a chattering of the entire equipment whenever they occur near the critical point. It will, of course, be understood that the balancing as such, of the outputs of the two photo-tubes Hi l and W5 occurs merely by balancing of the grid and cathode of the thyratron B26 and effecting the opening and closing of the contact 66% according to whether or not said thyratron conducts.

The power supply for the foregoing equipment is of any conventiona1 sort by which a rectified and reasonably smooth direct current is supplied by the rectifier 680 to the conductor 61'! from the alternating source 672 and by which a small volt-

Claims (1)

1. THE METHOD OF CARRYING OUT A CHROMATOGRAPHIC FRACTIONATING OPERATION EMPLOYING A SERIES OF SOLVENTS IN CONJUNCTION WITH A COLUMN, COMPRISING THE STEPS: WITHDRAWING SOLUTION FROM A FRACTIONATING COLUMN; PASSING THROUGH SAID SOLUTION OF BEAM OF RADIANT ENERGY OF A CHARACTER CAPABLE OF BEING PHYSICALLY AFFECTED BY A SELECTED

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