US2459869A

US2459869A - Crystal growing apparatus

Info

Publication number: US2459869A
Application number: US689672A
Authority: US
Inventors: Carl J Christensen; Albert C Walker
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1946-08-10
Filing date: 1946-08-10
Publication date: 1949-01-25
Anticipated expiration: 1966-01-25

Description

Jan. 25, 1949, C, J, CHRISTENSEN E-l-AL 2,459,869

CRYSTAL vGROWING APPARATUS 1 Filed Aug. 1o, 1946 i4 sheets-smelt 1 @ses REVERS/N6 C. J. CHR/STENSEN /NVENTORS Ac WLKEA,

A T TORNE V Jari. 2.5, 1949.

Filed' Aug. lO. 1946 H0 TOR CONTROL AIECI'MNISH C. J. CHRISTENSEN ISTAL CRYSTAL GROWINQ APPARATUS 4 sheelts-sheet s l l l I l l I 0 l L ,4.-C`. WALKER Y Patented Jan. 25, 1949 CRYSTAL GROWING APPARATUS Carl J. Christensen, Summit, and Albert C. Walker, Short Hills, N. J., assgnors to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application August 10, 1946, Serial No. 689,672

This invention relates to apparatus for growing crystals from a nutrient solution and particularly to crystallizer systems of the circulating solution type which may be utilized for growing large single crystals in a supersaturated nutrient solution at a constant temperature. Such artificial crystals may comprise such crystalline substances as ammonium dihydrogen phosphate, ethylenediamine tartrate, dipotassium tartrate, Rochelle salt or other crystal substances, from which elements may be cut for use as circuit elements in such systems as electric wave filter systems, oscillation generator systems and other electrical systems.

One of the objects of this invention is to grow large single crystals.

Another object of this invention is to grow crystals continuously without interference from spurious or spontaneous seeding in the nutrient solution.

Another object of this invention is to grow crystals more rapidly.

Another object of this invention is to grow crystals at constant temperature.

Crystallizers may be utilized for producing synthetic crystals of piezoelectric quality. This involves the preparation of a suitable nutrient solution and the seed crystals, and the manner of growing the full size crystals therefrom. The general principle is that of circulating past the growing surfaces of the crystal a supersaturated nutrient solution and maintaining it in supersaturated condition. The growing crystal continuously removes salt from the nutrient solution and this loss in salt is most frequently compensated for by adding additional solute in l amount suflicient to make up for the salt taken ing conditions with respect to the growing sur-V faces of the crystal to be grown, it has been found possible to grow, large clear crystals atta Vrelatively rapid rate in a supersaturated nutrient SOlutlOn.

6 Claims. (Cl. 23-273) cientofl solubility appropriate adjustments can A reciprocating rotary gyrator type of crystallizer may be conveniently utilized for growing the crystals in the supersaturated nutrient solution which may be contained in a suitable crystallizer tank. The gyrator may be mounted coaXially with respect to the axis of the crystallizer tank and may consist of a rotatable shaft carrying one or more crystals mounted thereon by means of stainless steel Wires or pins, for eX- ample, inserted in the crystal and carried by the rotatable shaft. Heat may be supplied to the nutrient solution from a heating resistance coil mounted immediately beneath the outside bottom surface of the crystallizer tank, the heat being applied mainly at or near the center of the cone or dish-shaped bottom only of the crystallizer tank. The rotation of the gyrator forms a vortex in the solution along the aXis of the tank and the spurious or spontaneously formed seeds are concentrated in the center of this vortex and drop to the center of the tank bottom or slide down the sloping bottom to the lower central point or inlet where the heat supplied at this location may cause such spurious seeds there located to dissolve, while the crystal mounted on the gyrator shaft continues tovgrow in the upper supersaturated region of the nutrient solution. Y v

Certain crystals may be grown more satisfactorily in a solution held at some specic constant temperature, rather than over a range of gradually lowered values of temperature. To adopt the crystallizer to a constant temperature growing schedule, the solution may be made to flow in a cycle from and back to the crystallizer through the following units: A saturator held at a slightly higher solution temperature than that of the crystallizer tank solution, a lter to remove all but the microcrystalline material from the solution received from the saturator, a heater tank to raise the solution slightly above the saturation temperature and dissolve all microcrystalline material, and a pump to deliver the clear refortied solution to the bottom of the crystallizer tank. The 'spent solution may ow'by gravity from the to'p region of the `crystallizer tank back into the saturator. The s'everal connecting links and tanks may be suitably heat-insulated to prevent spurious seeding. The foregoing description is in terms of a solute with a positive temperature Ycoefficient of solubility. For solutes with a negative temperature cocinybe made in the relative temperatures of the'variali beine.

ous parts of the crystal 112er apparatus and the surrounding ambient conditions.

When the nutrient solution in the crystalliaer vessel is adapted to the constant temperature growing schedule at a suitable temperature, the solution may be kept in supersaturated condition at that temperature. by inl allais-:ls referti; ed solution into. the bottom the crystallizer tank and permitting the spent or used solution therein to overflow through an outlet near the top of the crystallizer tankirlto ill-le Saturator tank'where the solution is resaturated with 4additional salt before being returned through unsaturator vessel to the crystall Y necting conduit pip-es and apparatus between the .three vessels mentioned mayl be' heat insulated and also may be additionally heated4 byV suitable means in order` to prevent undesired crystallization in the circulating huid. Y

The apparatus may continuously supply a so1u tion or thee nutrient material folglowing crystals atfconstant temperature, and it particular-l?? Suitable. for use. with .Salts having. unusual tem- Parature-.solubility relatieesandithese highly suscent-.ible taist-ernal erysilal strains occurring with temperature changes- .Alse muehlareercrystals .o mereerrstals may besrewn a singleL operationbeeauseiiieamount .of available salt for the' crystal growth relatively ree. The au stratus mar employ three; main units.. namely; a eilrstelllzer utilising; the principle. or moving. the growing crystal through the.- solution. a. sat-manor te ep I and a heaterto raisethe reshly saturated.u er refertied salt solution to; a

.temnerature above the sat-unseen point temper-l at S01. as to avoid the ear a of` extraneous seed ysiels into` the crystallizer as theL .sel

exliersit after having .been in the saturator with its multlnlieitrei small, errstals.,. m miereseepie dimensions. Theselution news.; in a cycle from the. crystallizerie the Saturaion to the. unv Saunier-and back. t0 the enfsiallizer, additional Olved.- in the seillraiol te emanensate-.fer the. crystalline solute removed in. the elysiallizer.. A

The. e' talllzer apparatus. isr useful in growing lares erysials. iS4 .relatively inexpensive te eenstruct, requires relatively little power to operate, 1S...S..1.mnle in. control and. Operation.. is reliable. in results denendablef Qontrol?. and actuating elllllnmellt are used/ln its construction, has the ab ity to destroy souriant and snontaneeus seeds the. nutrient solution. and the results 0f the process lucyy 10e easily. observed at allstases Eel.'- a. clearer understanding of. the nature ci invention and4 the additional, advantages. features. and objects tluirlfof.x reference is made to thelfcllcwina description takertin, connection with 11e aeeomnanvins. drawing., in which. like Y 3- being. an elevation a1 view of the erystalliser andi @casu-ratortaken. approximately en the 1in-e 3jr3 1 Eis elevation is a1. more. detailed; View ofY the system Viii ,trete .in 1.. tez..

al views.v illustrating simplied views illustrating a circulating type crystallizer system comprising three interconnected vessels each containingV the circulating. nutrient solution l and consisting Vof a saturator tank 2, an unsaturator tank 3 and a crystallizer tank 4. The tanks 2, 3 and 4 may be tanks composed of stainless steel or other suitable material and provided with glass or other suitable covers E. Suitable conduit piping Vsuch as stainless steel pipes 6, 1 and covered with siutable heat nsulating `material 9 may be utilized to interconneetV the three tanks Y2, 55,' and ll. The nutrient solution l flowsin a cycle from the saturator tank t0 the-'unsaturated tank 3, tothe crystallizer tank 4 and back to the saturator tank 2,'as indicated by the arrows shown inthe drawing.

' The saturator may comprise a suitable tank 2 having an` inlet opening connected with the conduit Bidisposed adjacent the top level of the nutrient solution l contained in the saturator tank 2-, as illustrated in Figs. l., 2 and 4; and having an outlet openingr connected with the conduit 1 disposed belowthe top level of the nutrient solution I contained inthe saturator tank 2 as illustrated in Figs. l, V2,.'and 4. Y- The overflow solution l may flow under the inuence of gravity iron; the outlet in crystalizei tank is through the inlet opening in the saturator tank 2 by'way of the inclined conduit. pipe 6 which interconnects the two YVessels 2 and and the solution i in the saturator tank 2 may ilow into theA unsaturator tank 3 by way of the conduit pipe 'l which interconnects the two vessels 2 and 3. A lter l0 Whichvemay comprise an inner ne screen!! surrounded by a coveringcloth i2 may be placed in the saturator tank 2 over the inlet to thepipe 1 in order torlter the nutrient solution l entering the unsaturator tank 3 from the saturator tank 2. A quantity of excess solid salt l5 may be maintained in the bottom region of the saturator tank 2 in contact withthe nutrient solution l therein in order that the nutrient solution I may be provided withadditional solute for making up Vfor the'loss or salt as taken from the nutrient solution i. in the process oirgrowing the crystals i-I inthe crystallizertank ll. ln. order that the nutrient solution'l contained in the saturator tank` 2 may take intosolution a suffit additional quantity of the solution i. in saturator tank 1 continuouslyv maintained at a suitable'elevated temperature by means ofV a suitable heater Eil which, may be disposed adjacent the outside bottom surface ofthe saturator tank in the central region thereof, as illustrated inFigs, l, 2 and 4.

The heater 2li may comprise a resistance coil typev electric heater of suitable heated bye; suitable source of current supply 2i and controlled-by'a suitable relay 22, power sup y source foonduotive connections 2li and thermos-tat 25 having its, heat sensitive element 2S disposed in the.- nutrient solution l in order to maintain the temperature thereof at a suitable value which may a constant or nearly constant value of temperature. As an illustrative example, the thermostat 2liv and heater may be set to'lnainu tainv the tcmnerature or" the solution l in the .saturator tank 2 at a temperature oi the order tween, thev saturator tank Z and the crystallizer tank# will be determined according,r te the nature of the -solution I, and of the crystal I1 to be grown, vand the degree of supersaturation of the solution I in tank 4 which can be tolerated without causing disorderly crystal growth in crystal I1 orthe occurrence of spontaneous seeding in the crystallizer tank 4.

One or more propeller blades 3B may be disposed in the nutrient solution I in saturator tank 2 for stirring the solution I continuously in contact with the excess salt I5. The propellers 3l) may be secured to a revolving shaft 3I and conveniently driven by a suitable electric motor 32 which may be clamped or otherwise attached to the` saturator` tank *2 as by a bracket 33. The saturator tank 2 may be provided with a suitable cover or lid 5 which may conveniently be composed of glass or other suitable transparent material that will permit inspection of the contents of the tank 2. The conduit pipe 1 surrounded by suitable heat insulating material 9 connects the filtered solution outlet of the saturator tank 2 with the unsaturator tank 3.

As illustrated in Figs. l, 3 and 4, the unsaturator or superheat tank 3 may comprise a suitable tank 3 having a solution inlet opening connected with the horizontal conduit pipe 1 disposed at the side of the unsaturator tank 3 that is adjacent the saturator tank 2. The filtered and resaturated solution I from the saturator tank 2 ows through the interconnecting conduit pipe 1 into the unsaturator tank 3, the direction of flow of the solution I being indicated by the arrow.

A suitable diaphragm type pump 40 submerged in the solution I in the unsaturator tank 3, as

illustrated in Figs. 1, 3 and 4, may receive the nutrient solution l through an open-ended inlet pipe 4I and pump the nutrient solution I therein through the solution outlet conduit pipe 8 extending through the bottom of the unsaturator tank 3 into the crystallizer tank 4. The diaphragm pump 4l! may be operated by suitable hydraulic drive means 42 applied theretothrough the pipe 43. One or more motor-driven propeller blades 30 may be disposed in the nutrient solution I in the unsaturator tank 3 for stirring the solution I thereinvcontinuously.

In order that the solution yI contained in the unsaturator tank 3 may be maintained in an unsaturated condition with respect to the solute therein and so that all seed crystals which may have passed with the saturated solution from the saturator 2 through the filter I0 will be destroyed, the temperature of the solution I may be maintained at a suitable value by means of a suitable heater disposed adjacent the outer bottom surface of the unsaturator tank 3 in the central region thereof. The heater 2U may comprise a wire type resistor of suitable wattage heated by a source of current 2| and controlled by a thermostat regulator having its heat sensitive element 26 disposed in the nutrient solution I. l

The crystallizer may comprise v,a tank 4 as illustrated in Figs. 1, 2, 3 and 4, the tank 4 having a solution inlet opening in thecentral portion of the bottom thereof, the inlet opening being connected with the heat-insulated conduit pipe 8 leading from the output of the pump 4I] which is disposed in the unsaturator tank 3 and which pumps the nutrient solution I at a suitable rate of ow into the Vcrystallizer tank 4. The outlet openingof the crystallizer tank 4 is disposed adjacent the upper level of the solution I'therein wherethe overflow solution I may flow under the influence of gravity through the vinclined heat-insulated conduit pipe 6 back into 4the saturator tank 2.

The crystallizer tank 4 may be provided with a cone-shaped or dish-shaped bottom having such a suitable inclination or slope that any spurious seeds i3 formed in the solution I in the crystallizer tank 4 may fall and gather in the region of the center of the bottom oi the crystallizer tank 4, or in the opening of inlet pipe 8, where they may be redissolved into the unsaturated solution I entering from the unsaturator 3 through pipe 8, or by means ci the unsaturated conduction layer of solution adjacent to the heaters 23. The heaters 23 may be disposed adjacent the central portion of the bottom of the crystallizer tank i and may provide suicient heat to raise the temperature of the conduction layer of the solution I adjacent to the heaters 2i) to an unsaturated condition, while leaving the upper regions of the solution I in a supersaturated condition for growing therein the planted crystals I? disposed in Contact therewith. The heater 2i) may comprise a resistance wire coil or coils heated by a source of :current 2l and controlled by a thermostat regulator 25 having its heat sensitive element 26 disposed in the supersaturated nutrient solution I in order to maintain the temperature thereof continuously at a suitable constant temperature.

The thermostat temperature of the solution I in the crystallizer tank ll may correspond to a xed value that renders the solution I supersaturated with respect to the solute therein.Y

For growing ammonium dihydrogen phosphate crystals I1 such a temperature may be of the order of about 38.0 C. for example, with correspondingly higher solution temperatures in the saturator tank 2 and the unsaturator tank 3 such as, for example, solution temperatures of about C. and 43 C. in the saturator and unsaturator tanks 2 and 3, respectively.

The crystal bars I1 are grown in the crystallizer tank 4 by moving the crystal through the supersaturated solution I thereby taking salt from the supersaturated solution l and depositing it in crystalline form on the outer surfaces of the crystal bars I1. In order to move the crystal bars I1 in the supersaturated solution I, they may be rotated about a vertical axis first in one direction of rotation and then in the oppositev direction of rotation. Such rotation tends to produce a vertical vortex in the solution I and the vortex tends to gather any spurious seed crystals I8 at the central part of the bottom of the crystallizer tank 4 where such undesired seeds I 8 may be redissolved into the solution by the heater 20 or by the hot solution entering the inlet from tube 8. The crystals to be grown into larger size bars I1 may be mounted on one or more wires or supports carried by a reciprocating rotary shaft 5I. A propeller type stirrer 52 may be mounted on the lower end of the rotary shaft 5I.

More particularly, the crystallizer 4 illustrated in Figs. 1, 2, 3 and 4 is a reciprocating gyratorv type of crystallizer which may be used for growing a planted seed crystal I9 into a larger sized crystal I1 from a supersaturated nutrient solution I contained in the glass or metal tank 4 or other suitable container. The container 4 as illustrated in Figs. 1, 2, 3 and 4 may comprise a tank 4 type supports 5I! seores to the centrally located and vertically disposed gyrator sliafty 5I, the ubpr portion of which may extend, through a Central' opening in t'he'ro'ontainer cover 5 and be there oarrie'd by a suitable bearing suoli as a ball bearing E5 and flange 5. The rotary gyrator 'shaft 5I may' bedrven by any suitable actua-ting sinulteneousi'" saisie erystsniser taaie t;

ineans suoli as; for example, a reversing electric motor 51 carried by a supporting frame 58 and Connected to the shaft Viii through a clutch 5S, the motor 5'! being geared' or otherwise coupled tothe gyrator' shaft 5l so that the shaft 5I may rotate at a suitable speed Vsuon as, for example,

four or incre revolutions per' minute, tbe dire@V or rotation of the 'sliait El being reversed every one, two or more of its revolutions, as desired; YThe power capacity required of the fnoto'r el is suioient to overcome the viscous drag effect of 'the crystals Il' moving through the nutrient solution l. A ball' bearing type' o mounting 55 may be'utilized when it is desiredY to reduce friction at points 5E whereV the gyrator 5r is hung. Y

A'lieAV reoiproeatingl rotary gyrator shaft 5I may be mounted coaxially with respect to the axis ofthe Cylindrical tank and may' consist of a ppeor rod'of inethylrnethaerylate resin, stainless additional crystallizer tank or' tanks' 4- 'maybe served in` the same nia'nner fion'i the saine 's'-tiirato'r and unsaturato'r' Atanks 2 and 3' thi-1sl ob# taining Va System iii' WlrioliA two' 1" more ySt/II" v ing tank-s' are'v supplied from asingle s"et of sa-tnvrater and unsatiurator tanks 2- and 3; y y l Tlfe temperature@ the r'ilitlnf solution I may be' ailltonffielly i regulated by a suitable there in oregulato 755"A having" its' heatesensit'ivf element steel' or other 'suitable material of tlie'order of one inch, more or less, indiarneter. To the shaft there may be attaenneda number of radial or other type` supports 5'@ upon Wiiioli tlfie growing Crystals Il 'may be r'nount'ed by thel stainless steelV Wires orY pins 5 or MBA extending into `holes pro-v vided in the'body of eacriof the crystals I?. The supports may take various forms as illustrated ii'ithe drawing. Y

The rotary motion of the gyrator 5I Creates a vortex in the solution i which bunches eX- tra'xi'eous crystal seeds I8 at the bottom of the erys'tallizer tank il where they may' be redis'solved into solutionein the' thin layer of unsaturated solution locally produced along the bottom part only' of the solution by a locally increased' temperatu're produced by the heater Ell or 6l. The' unsaturated layer of the solution Il isrcon'ned A r'nainly t'o' a loeatio'n immediately above the heaters Z Where the .spuriousseerd crystals' IB Yare aggregateu'.y only-a limited amount or neat is'appliedfrorn the heatersv 2B to a limited area on t-l'ie'` central bottom of the crystalliz'er tank 'v aiY Vperiod i ze extending' into' nutrient" SG1-unen I.. The

automatic'hea-t ontr'l and terri4V 'rature regulate ing equipment 20 to' 26-1'n'ay' eoiiip f ,any suitabletybe lof' tlierrnregulator 25, rla'y 22r and heater- 2li.` The thermor'egulator 2-5' may be *forA ege ariiple of the' standard inerurydn-glas's' tyrl,4 the temperature sensitive end 26- of Wli'ieli ie irisite'd in thermal Contact tvitllth nuti'ienlts'ol-ition I".- The thermoregulato'r 25 I'r'i'ay Vbe eoirieote'd by Source gaf for operaties .e reieygzz having e. een reet which is' connected erreur@ wien e sewer susrsiy source 2i suitable for nearing' the heater desirc'ry'fe':d,V While at the same timek the planted Y crystals il mounted above theY bottom region of the' tank 4- will grow in contac'tvvith" the super-Y situratedinutrient solution I. This u'se'fiilo'onA`4 dition comes'about by raising the temperature above the saturation temperature' only at the extreme bottom portion of` the crystallzerl t'anlv 'I? and" introducing suitably heated solution through the inlet pipe il at the lowest point of the ooneeshaoed bottom of the tank 4'.'

".Fne er'ystallizer container 4 maybe Composed ofls'tainless steel or glass capable of withstand= ing"4 heat applied to the bottom thereof `andl prof seeding andV ,tok disserve any email seed" eryst'ais which may have passed througii the lfilter l0.

Tli S''lt'oii I is then pumped by the '4Ut at an unsaturated teinperatiire'iroxn the une s'atui'atortank'int'o the c ily'stalliz'er' t'anl: 4 at a.

l rateof flow Whicnis suii'lient'to' provide addi# tional salt asmay be needed duringthecrystal*- uzeuon of' me saiten' theY Crystals f1 in' une orystallizer' tankv Il. Therateof ovv may cor'- respond to a Value' suieient yfor the purpose mention-ed suoli as' for` exaniplej 1G t'o liters Derlio'ur; and Will be dependent upon the teni; perat'u're olii'erentnia; lV between the" solution I saturate? tank- ,22 and thjefcrystalliz'e'r 4"; Each' or the three tanks 2', 3y and 4f has anidee een-deur temperature @entre 1mg in' moete-t 25 and 2t' for inuiep'e'ndetiy" cuitrailin'gAh tire temperature of the solution i therein. As an illustrative example, the solution I in the satu-V saturator tank 3 may be controlled by its ther-Vy mostat at any convenient temperature above the C. mentioned, such as a temperature from 42 to 46 C., and the solution I in the crystallizer tank i may be controlled by the thermostat 25 lat a suitable crystal growing temperature below the 40 C value mentioned, such as, for example, a value of 38.0 or 39.0 C., the latter being a temperature value that'corresponds to a supersaturated condition for the solution I in the crystallizer tank 4.

In addition to the heaters 2t, heaters 6I in the form of resistance wire coils 6I may be applied around and along parts or along the whole of the piping 5, 'i and S connected between the -saturator tank2, the unsaturator tank 3 Vand crystallizing tank in order to maintain the temperature of the solution i in the pipes 6, I and 8 above the saturation temperature of the solution I thereby to prevent crystallization of salt therein. The heater coils 5l may be energized by any suitable power supply 62 and control means 53.

It will be noted that the apparatus illustrated in Figs. 1 to 4 may be used for growing large single crystals il from thenutrient solution I and may consist broadly of three interconnected vessels, namely, the saturator 2 where additional solute is added to the solution I, the unsaturator 3 where the solution l is brought to such atemperature ,condition that the solution I becomes less than saturated with respect to the solute, and the crystallizer i wherein the solution l is adjusted in temperature so that it becomes supersaturated and wherein seed 'crystals I 9 are planted so that they may grow into large size crystals i7 by ytaking solute from' the nutrient supersaturated solution i. Means are provided to cause the nutrient solution I to flow in the cycle from the saturat-or 2 to the unsaturator 3 to' the crystallizer i and back to the saturator 2. Means may be provided to maintain the solution in each. of the three vessels 2, 3 and 4 at a predetermined independent temperature. The saturator 3 may be provided with a stirring device 30 for mixing the excess salt I 5 with the solutionV i therein and a lter l@ may be tted Iover the outlet of the saturator 2 leading to the 'unsaturator 3. The unsaturator 3 may be provided with apump 4B the nuid handling part of which may be entirely submerged in the unsaturator tank 3.v The crystallizer d may have a coned or dished bottom with the unsaturated solution i from the unsaturator 3 entering the lowest point at the apex of the cone or the vcenter of the dish. The crystallizer L', may be equipped with a gyrator the shaft 5l of which is mounted vertically with the axis of the -crystallizer tank 4, with means 50 or other suitable supports attached to the gir-fA rator shaft 5! on which seed crystals I9 can be mounted for growing into individual large crystals i'I. Suitable means such as an electric motor 5'I may actuate the gyrator shaft 5I either in one direction of rotation, or alternatively in.

condition of the solution i adjacent fto the growing crystals I'I can be maintained. Y

In connection with temperature control con- -l siderations, it has been found that when the entire apparatus is operated in a temperature controlled room, there are several alternative ways of maintaining steady temperature in the solution I in the crystallizer 4 other than by means of the mercury thermoregulator 25 and associated external heater 20. To understand this it maybe appropriate to note that it is' of course necessary to supply sufncient solution from the unsaturator 3 by means of the pump Lili so that the crystals I'I will grow as rapidlyY as possible. Once this rate of flow of solution has been -established as a minimum permissible, and with' a suitable constant ambient temperature, it isthen possible to maintain a steady crystallizer temperature by three different, but somewhat interrelated methods. 'One way of accomplishing this is to set the ambient temperature suiiiciently low so that with a minimum solution ilow then for a given rate of flow of solution I greater than required to balance the heat loss to ambient, to adjust the fan speed' to balance heat supply and' heat loss. A third way is to supply a small, nxed'and Vcontinuousv heat flow into the tank 4 5" from-a small external heater 23 mounted onthe botto'mof the tank 4, this amount of heat being just sufficient to offset the heat loss to the ambient, when the pumping rate is insuiiicient to 'supply all the heat that is needed. These three alternatives provide a flexibility of control, and a somewhatmore steady temperature under certain conditions, than that provided by the mercury thermoregulator 25 and associated external heater 20. i y

Fig. 5 is a sectional View illustratinganother form of crystallizer 4 comprising a magnetic driving arrangement that may be utilized for growing a crystal in a rotary gyrator type ofmount., 60.. In this arrangement, the growing crystal l1 may be turned or rotated about a longitudinal vertical central axis Z-Z, thereoL the crystal II 'being carried by one or more horizontal wires mounted in the two vertical side plates of a rectangularshaped stainless steel rotatable frame .15. The frame I0 may be carried by the shaft 5I suspended fromV a ball bearing associated with the container cover 5. The frame It may be rotated by means of the shaft 5I as illustrated in Figs. l to 4, or by means of a magnetic clutch arrangement as illustrated in Fig. 5. coupling arrangement as shown in Fig. 5 may include a driven magnet bar 1I disposed in an enclosing protective glass tube 72. The glass tube 'I2 may be secured by cement or other suitable adhesive means to` the bottom plate of thereotangular frame gyrator l0. A coaligned motordriven .Alnico U-shaped magnet 'I3 disposed very closely adjacent theoutside glass bottom .surface of the glass tank 4 may cooperate with the driven magnet bar II disposed insideV the tank 4 in order to rotatethe gyrator 'I0 and crystal I7 simultaneously. The clearance between the driven magnet bar 'II andthe upper faces of the U -shaped driver magnet I3 may be made 'T very small. The rotating gyrator frame I0 func- The magnetic ausw .11 tions `as a support Yfor the crystal IJ and also as a means for stirring the .nutrient supersaturated solution 'I containedl'in the crystailizerftankwl I desired, the .frame le -may be equipped with one vor `more propeller blades' 52 disposed on the Y two vertical sides and the .horizontal 'bottom plate thereof for obtaining an vincreased `and uni-V form circulation of the nutrient solution l in theV crys'ta-ll'izer tank L As illustrated inFig. 5, the crystal l1 may be moved in the supersat-urated nutrient solution l4 about its own axis with frequent reversals in its direction of rotation by means of the magnetic coupling, operating through the glass bottom of the container 4, to the reversiblyVV driven .magnet 73. .An economy oi vpower results from Vmoving the crystal il., rather than'moving vthe combined container 4,

' liquid l and crystal ll. The arrangement involves a uniform circulation of the solution vI and a movement of the` crystal Vil through the body of the nutrient solution I by turning in the soluf tion, ratherV than mainly a movement -of theY solution l around Ythe crystal 'l.

such solutions, have a rhighly stabilizing effect on the uniformity land clarity 'of :growth of the crystals Il vgrovvnrom supersaturated solutions l of such potassium tartrate-` Suche solution -I may be -plftfmai'ed vby burning or caramalizing the solid salt, dissolving it into'the solution l., nl tering and utilizing .it without attempting to remove the soluble colored material which 4is prob ably decomposed. tartaric acid. Y Crystals Y' l?! grownfrom this Vhighly colored solution -heal Y readily and vgive Vclear crystalline materialVV Fig. 6 is a view of another lformo'f vcrystallizer Y tank 'arrangement which may be utilized .for

growing crystals `|1 from Ya supersaturated nutrient solutionjl by movement of the crystal l"| through Ythe body of the nutrient solutionY If.'

.es illustrated in Fig. 6, the crystal I`J is movedV through the nutrient solution Irin a .swinging type of` motion, the crystal i7 beingV moun-ted onV a trapeZe-like suspensionY "l5 aflixed by suitable pivots lr6 to the underside of the contain-er cover 5, the suspended trapeze l5 being adapted to sWing-backand forth Within the containerY 4, thereby swinging the suspended vcrystal l1 through the supersaturated nutrient solution l- Suitable reciprocating means may Abe `utilized forV actuating the suspension l5, such as means rocking the tank 4 on a tilting table 'l1 actuated about coali'gned shafts 'TB by any suitable reciprocating driver means, such as for example that illustrated in Kjellgren Patent Re. 19,697 dated September 10, 1935, Fig. l1V at ll to 2l. nBy slightly tilting the table 11 to and fro. about the common horizontal axis of the shafts 1'8, the vfreely swinging trapeze T5 causes the growing crystal l1 .to move or swing back and forth through the `nutrientY solution .l thereby providing conditions `for `uniform growth of the crystal I'1 with little motion imparted to the solution fl beyond some desirable circulation. The crystal JI'I may .be mounted on such as illustrated at '18 in .-Fig. 5 in order to .prevent twisting of the mounted crystal l1, relative to the Vsupporting Wire 5U itself.

v'While the invention has been described parY composed organic tartrate, either y"through overheating of such solutions or through caramelizecl burning 'of the solid potassium tartrate Ysalt in Where the nutrient solution .i comprises ammonium dihydrogen phosphate, various substances Vsuch asainmonium sulphate, maybe added in suitable amount in order to produceV various effects on the growth 'habit of the crystal il, as described inan application, Serial No. 598,691, iiled June All,` 1945, 'by A. N. Holden.

-While in Figs. .l to 6 various arrangements for the Ycrysi'fallizer lifhavebeen illustrated, examples Yo additionaliorms are'given in an application for Crystal growing apparatus, Serial No. 598,691, filed June 1'1, 1945, by A. N. Holden, kand -n an application, Serial VNo. 598,69'35,- liled June lll, i945, by vC. J. AChristenseny now United States Patent No.2,2l42j755, dated June 8, 1948.

Although this invention 4has been described and Villi'istrated in relation. to specic arrangements, `it is to be understood that it is capable of one .or morestainless steel wires which mayA be of 'any suitable .square or other bent lform,

application 'in other organizations and 'is there- 'fore not to be lirnt'eli 'to 'the particular embodiments disclosed.

What 'is claimed .is z

if A jcrystallize'r system comprising aplurality of more than two separate interconnected vessels each having "inlet `and outlet Vopenings and ihciuding a saturar-or vessel, an unsaturator or sup'erheat vessel, and lacrystailizer vessel, and con-V duits 'cyclically 'connecting said vessels 'in the 'order'V from said saturator vessel tofsaid unsaturator vessel 'and from said unsaturaitor vessel to said Vcrystallizer vessel and from said .crystallizer 'vessel back to said saturator vessel, said conduits comprising a conduit connecting said outlet opening Ain said saturator vessel with 'said inlet opening `in said unsaturator vessel, a conduit connecting Asaid outlet opening in said unsaturator vessel to sa'idfinlet opening'in .said crysta'l'lfzer vessel, sjaid last-mentioned inlet openingv being an opening extending Athrmigl'i the lower# most part of the bottom of said crystallizer vessel, 'and a conduitV connecting said outlet opening in 'said crystallizer vessel lvvithsaid inlet opening in said s'aturator vessel, a 'tempera-ture sensitive devic'erdi'sposed `in 'said saturator vessel, -a heater electrically 'connected with 'said temperature sensitive device yand disposed adjacent Ysaid sat# Vu'rator vessel, a temperature sensitive device disposed in Said uh'satura'tor vessel, Aa heater electrically connected With -said last-me`nftioned temperature sensitiver device and disposed Vadiacerit 'saidV unsatu'rator vessel, said `crystallizer vessel having disposedfthere'in Work carrying .means7 a temperature sensitive device disposed lin-said crys-` talliz'er vessel, and "a heater electrically connected with 'said 'last-mentioned temperature sensitiveV device and disposed adjacent said bottoni .inlet opening 'in said crystaliizer vessel, said vtemperaturesenstive devices'beng independently .reu spo'nsive 'to ,predetermined temperature values. '2. A crystallizer system compris-ing Aa plurality of more 'than two ,separately enclosed interconn'ected 'vessels each Vhaving inlet and outlet openings a'nd including :a saturator vessel, an unsat- .urator or superhea't vessel, and a crystallizer Vesaasasce sel, and conduits cyclically connecting said vessels in the order from said'saturator vessel to said unsaturator vessel and from said unsaturator vessel to said crystallizer vessel and from said crystallizer vessel back to said saturator vessel, said conduits comprising a conduit connecting the outlet opening in said saturator vessel with the inlet opening in saidunsaturator vessel, a conduit connecting the outlet opening in said unsaturator vessel with the inlet opening in said crystallizer vessel, said last-mentioned inlet opening being an opening extending through the bottom of said crystallizer vessel and said bottom being a dish or cone shaped bottom having downwardly sloping surfaces and having said lastmentioned inlet opening positioned substantially lat the apex or lowest point thereof, and a conduit connecting the outlet opening in said crystallizer vessel with the inlet opening in said saturator vessel, a pump connected with one of said conduits, heating means disposed immediately adjacent at least a part of said conduits, heat insulating means covering at least a part of said conduits and vessels, a temperature sensitive device disposed in said saturator vessel, a heater electrically connected with said temperature sensitive device and disposed adjacent said saturator vessel, a temperature sensitive device disposed in said unsaturator vessel, a heater electrically connected with said last-mentioned ternperature sensitive device and disposed adjacent said unsaturator vessel, said crystallizer vessel having disposed therein work carrying means, a temperature sensitive device disposed in said crystallizer vessel, a heater electrically connected with said last-mentioned temperature sensitive device and disposed adjacent said bottom inlet opening in said crystallizer vessel, said temperature sensitive devices being independently responsive to predetermined temperature values.

3. A' crystallizer system comprising aplurality of more than two separately enclosed interconnected vessels each having inlet and outlet openings and including a saturator vessel, an unsaturator or superheat vessel, and a crystallizer vessel, and conduits cyclically connecting said vessels in the order from said saturator vessel to said unsaturator vessel and from said unsaturator vessel to said crystallizer vessel and from said crystallizer vessel back to said saturator vessel, said conduits comprising a conduit connecting the outlet opening of said saturator vessel with the inlet opening in/said unsaturator vessel, a conduit connecting the outlet opening in said unsaturator vessel with the inlet opening in said crystallizer vessel, said last-mentioned inlet opening being an opening extending through the bottom of said crystallizer vessel and said bottom being a dish or cone shaped bottom having downwardly sloping surfaces and having said last-mentioned inlet opening positioned substantially centrally at the apex or lowest point thereof, and a conduit connecting the outlet opening in a side of said crystallizer vessel with the inlet opening in said saturator vessel, a pump connected with one of said conduits, heating means comprising electrically heated resistors disposed immediately adjacent at least a part of said conduits, heat insulating means directly covering at least a part of said conduits and vessels, and a stirring device disposed in each of said vessels, said saturator vessel having a iiltering screen disposed over said outlet opening thereof, a temperature sensitive device disposed in said saturator vessel, a heater electrically connected with travel said temperature sensitive device comprising an electrically heated resistor disposed adjacent said saturator vessel, a temperature sensitive device disposed in said unsaturator vessel, a heater electrically connected with said last-mentioned temperature sensitive device and comprising an electrically heated resistor disposed adjacent said unsaturator vessel, said crystallizer vessel having disposed therein a reciprocating gyrator type work carrying means mounted substantially coaxially with respect to the vertical axis of sad crystallizer vessel, a temperature sensitive device disposed in said crystallizer vessel, a heater electrically connected wtih said last-mentioned temperature sensitive device and comprising an electrically heated resistor disposed adjacent said bottom central inlet opening in said crystallizer vessel, said temperature sensitive devices being independently responsive to predetermined and diierent temperature values.

fl. The method of growing crystals from nutrient solution circulating in contact with excess solid salt disposed at a point along the path of of the solution passing successively through a saturator stage, a separate superheat or imsaturator stage anda separate crystallizer stage, which consists in circulating the solution cyclically in a continuous path of travel passing successively from the saturator stage to the unsaturator stage, from the unsaturator stage to the crystallizer stage and from the crystallizer stage backto the saturator stage, moving the solution in contact with the excess solid salt in the saturator stage, heating the solution in the saturator stage to a temperature value suiciently above its saturation point temperature to render it sufciently unsaturated to add additional solute thereto from the excess solid salt therein, heating the solution in the unsaturator stage to a different temperature value above said temperature Vahle in the saturator stage and suliciently above its saturation point temperature to render it sufliciently unsaturated with respect to the solute therein to dissolve crystalline material, moving the heated solution received from the unsaturator stage upwardly into the lowest part only of the bottom of the 4body of solution in the crystallizer stage at a rate of iiow suincient to-replenish used solute removed from the solution by crystallization in the crystallizer stage, heating the lowest part only of the body of solution in the crystallizer stage at a temperature suitable to maintain the lowest part only thereof unsaturated at a temperature value suficiently above saturation point temperature to curtail crystallization and suitable simultaneously to maintain the upper part thereof saturated at a temperature value sumciently below saturation point temperature to permit crystallization and growth of crystals, and moving the crystals in contact with the saturated upper part of the solution in the crystallizer sta-ge.

5. The method of growing crystals from nutrient solution circulating in contact with excess solid salt disposed at a point along the path of travel of the solution passing successively through a saturator stage, a separate superheat or unsaturator stage and a separate crystallizer stage. which consists in circulating the solution cyclically in a path of travel passing from the saturator stage to the unsaturator stage, from the unsaturator stage to the crystallizer stage and from the crystallizer stage back to the saturator stage, stirring the solution in contact with the excess solid salt in the saturator stage, heating it tirezs'oiution in the saturator Stege to' a, temperature value suiiiciently above its seturetion point temperature to render it .su-clently unsatur^ted Y to a'd'd 'additional solute thereto from 'the 'eX solid salt therein, ltering the 1solution 's'lf'cie tly to remove `solid crystalline material therefrom in passing from the vsafmrra't'or 'stage 'to the un'- sturator stage, heating the :solution 'ther-1nvv- Salturator stage to a Alierent teinfperture 1.1 above 'saliti tempera-ture value in "tlfle sat Se 'stage and suicien'tly above VAits satuiiati'on porn-t temperature to render it isui'ciently unsaturated to 'dissolve crystalline material in "the solution p'ssin-'g through the unsaturator s'tage, moving the heated 'solution from the unsaturator rstage upwardly into the lowe'strpa'rt only 'of 'the 'bottom off the bodyY of solution in fthe 4'oryst'stll-Zler stage, heating'the lowest part only of the body of so@V lli-tion in the crystellilzer stage 'at e. temper-'af suitable to maintain the upper part thereof est u'rated at le, temperature velueV suiiiciently below v saturation point temperature "to permit',V :crysteb lzation and 'growth of the Crystals therein, and moving the crystals in Contact with the Seite rated upper part of rthe slution the oiysteh lizer stage.

6. The method of' growing-.mounted crystals from nutrient solution circulating in oontaotwith excess vsolici salt 'disposed at point along the path 'of travel of the solution :passing lsuc'oes;n sively through a saturatorrstage, a separate su-` perheat or unsaturatorstage and @separate crystallizerV-'stage which consists in rcirculating the solution cyclicaflly in a continuous path o'fV travel Y passing successively 'from the saturator s-teeeY to the `unseturator stage, from Vthe unsaturator stage to the separateV crystallizer Ystage and from the crysvterllizer stage back to the 'saturator steige, stirring the solution in contaotiwith excess solid salt :in the saturator stage, heating Ythesolution in the saturator stage to a, temperature value sufficiently above its saturation point tempera"- ture to renderit suioiently unsaturated to add sucient additional -solute thereto from Vthe -excess -sold sal-t therein `-to replenish -used solute removed from the solution Vby crystallization in emite the `@notamiger stese, loitering ,the Viifepierirshet solution sufeienuy it@ Vfemm/e sono uws-talune n passing from the Ystage to the unsaturtor istage, stiriir'r'g hesoiirthe eetmeter-'stage and suiiioietly altrove its st- Tteinperatuire to itis iii'- ui on 1p ated with -resp'eet 'tothe fsthee to' 'dissolve 'Crystalline material, 1mm/1mg the h )ed saumon nom the ummm-later stese of the @metals therein, revovmg 'the rexystais 1in contact with vthe `seltureterl @upper inert of 1the l, solution in the orystellzer stage; and heating the solution intermediate the unsatmator and orystallizer stages to a temperature vaiuesufciently ab'ove saturation point temperature .to render it sufficiently .unsaturated `to*dissolve crysltarline inerterialft-here'n. Y Y

CARL -J. CfIfmISfIiENSEN. `ALBER'f-ll REFERENCES 'l CITED l The ioEloWin-'g' refierencs ferrefof 'rebord '-t-le le of -this 4limitent: v Y Y STATES OTHER' REFERENCES Y Comptes Rendus (Fit-i., v01. YLoiri-1897, p. eee.