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II/ECI Unit Operations Review
Crysta Ilization by Herbert M. Schoen, Radiation Applications, Inc., New York, N . Y., and Jack Van den Bogaerde, American Cyanamid Co., Stamford, Conn.
A spiral zone melter, wetted-wall crystallizer, and centrifugal crystallizer
clearly
L I T E R A T U R E in the crystallization field continues to grow rapidly, keeping pace with the general explosive growth of scientific literature. T h e number of references cited in this review is approximately the same as in past years, but a more careful screening of the literature was required to maintain a review of reasonable size. This was accomplished by deleting or covering very selectively such subjects as : crystallization in polymers, crystallization in metals and melts, crystallization equilibria, epitaxial growth, crystallography, and whiskers. Crystallization in the sugar industry is treated lightly, as the authors feel that it is not of wide interest. T h e literature cited is approximately half U. S. and half foreign. However, examination of references not reported here shows that foreign literature predominates the field. This review covers the period 1959-1960. There continues to be a paucity of information which could be considered the “engineering science viewpoint.” Zone melting and single crystalgrowth continue to have widespread interest. Studies in the areas of growth from the vapor phase and effect of impurities and additives on crystal growth appear to be exceedingly fruitful subjects for investigation.
Reviews and Books
A volume on crystals and crystal growing appeared in 1960 (SA). A second edited volume on Russian research in crystal growth (8A) appeared in English translation. Growth of oxide single crystals containing transition metal ions (4A), monocrystals of seignettoelectrics (6,4), and nucleation, growth, and microstructure of thin films (7A) were the subjects of three recent revieiv articles. Reviews of the industrial uses of crystal habit modifiers (3‘4) and of the contemporary views on sugar crystallization ( 7 7A) were presented. T h e dependence of crystal form on the rate of crystallization (7UA) was the subject of a theoretical review. A recent review (9‘4) discussed the factors affecting the design of crystallizers. T h e subjects of supersaturation, im-
show strides
in
the
equipment
area
component metastable incompressible fluid were derived ( 3 B ) , Homogeneous nucleation occurs a t low supersaturations, while at higher supersaturations departures from the classical theories are predicted. ,4 polar surface of uniform sign was found to decrease the entropy effect in ice nucleation (5B), requiring a large supercooling for nucleation at the surface. T h e kinetics of nucleation of nonNucleation coherent layers on a parent crystal lattice An experimental system comprised of a were considered (75’B). Aqueous KBr turbulent jet, in which a dilute vapor and NaCl solutions cooled slowly yielded issuing from a nozzle is rapidly quenched a small number of nuclei (7B). Vigorous by a cool annular gas, was used to produce agitation of these supersaturated solunuclei under steady state conditions (86’). tions caused intensive nucleation. NuUsing this system, experimental data cleation studies in a silicate melt (2B) were obtained for dibutyl phthalate and and in the precipitation of PbSOl at n-octadecane which were in agreement room temperature ( 7 7B) were reported. with the theory of Becker and Doering. Crystal Growth Homogeneous nucleation did not occur until supersaturation exceeded 450% in Uniform size insulin crystals for injecthe crystallization of copper from liquid tion were grown by seeding with a calcubismuth ( 9 B ) . T h e size effect in hetcrolated amount of insulin crystals (74C). geneous nucleation was reported ( 6 B ) in T h e amount of seeds required is calcuthe literature, while nucleation of AgCl lated according to the following formula: was the subject of a recent thesis (7UB). P = l[dP3/(d,3 491 O n the assumption that crystallization where P = weight of seeds centers of sloivly crystallizing organic I = weight of product desired liquids consist of active impurities d, = size of seed crystals coated with a crystal layer of the subd, = size of product crystals destance under investigation, an experisired mental and theoretical investigation of
purities, agglomeration, and rate of growth were included. Zone refining and allied techniques were treated in a recent book by Parr (7.4). Thirty-five references were given in a revierv of the mechanisms of crystallization (2,4). Crystallization is shown to proceed by a chain mechanism. This process is comparrd with other types of chain processes.
+
nucleation kinetics was conducted (73B). T h e kinetics of the reaction were found to be first order. Another study by the same author (72B) indicates that the size of the impurity particles is of great importance. Linear relations were found to exist (7B) between the reciprocals of the saturation and supersaturation temperatures and between the logs of the concentration a t saturation and supersaturation in the systems NaC1-HIO, KCILH20, Na2SOI-H*0, and KzS04HzO. Supersaturation was determined by observing the first visible nuclei. The activation energy of nucleation in sintered .A1203 was reduced by the addition of Ti02 or hlnO (4B). Nucleation in aqueous solutions of K Y O , (76B) and KCI (74B) was studied. T h e properties of a critical nucleus in a two-
Spontaneous nucleation must be avoided for the equation to be valid. T h e growth rate of benzene in capillaries was determined for undercoolings ranging from 0.01” to 1.5’ C. (73C). General formulas were presented for diffusion-limited growth rates of precipitate particles (7UC). In another study (5C), the linear growth of different faces of citric acid crystals was observed microscopically while a supersaturated solution was circulated a t high velocity around the crystals. T h e concentration distribution around growing crystals was observed by a phase contrast method ( 8 C ) . T h e existence of an ordered boundary layer of 50 to 70 microns thickness was observed. Table I lists some additional noteworthy crystal growth studies. VOL. 55, NO. 2
FEBRUARY 1961
155
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Unit Operations Review
Table I.
Table II.
Growth
Subject Kinetics of solidification from nonmetallic liquids Hydrothermal synthesis of sheelite Dendritic growth of Ge Growth of BaTiOv from KF solutions Growth in NaAIO? solutions Growth of precipitates Precipitation in homogeneous solution Crystallization in low-pressure polyethylene Dissolution rate of crystals
Vapor Phase Growth Recent studies of growth from the vapor phase are given in Table 11.
Zone Melting
A number of patents were issued relating to new techniques and equipment for zone melting. Zone melting and purification of conductive materials is achieved by means of Joule heat (76E). The passage of an electric current through the material raises the temperature to the melting point. The length of the melted zone is controlled by means of heat sinks at both ends. Passage of the zone is accomplished by adjusting the heat absorption of the sinks and a number of other techniques. An improved cross-flow continuous zone melting device is described in one of Pfann's recent patents (75E). The problem of contamination from the container has been avoided by means of a n electromagnetic field which suspends the molten zone of a conductive material (74E). A zone melting furnace used to grow single crystals without the use of a seed has been patented (9E). Gallium arsenide was grown by horizontal zone melting (17E). The incidence of dislocations was reduced by careful control of the growth conditions. A method for obtaining very high purity
Vapor Phase Growth
1 56
Single Crystals
Ref.
Material
Ref.
AlF,, anhydrous A1203 whiskers CdS CdS, pure single crystals Au, uniform single crystal films K single crystals NaCl TiCls ZnS
(7D)
Mg, containing N2 Ni ferrites Polyoxymethylene Quartz Sn, Zn,Ag, Au, Cu
U0F) (8F) (9F) (6F)
(SD)
(8D) (SD)
(2D) (6D)
(4D) ( 1 D)
gallium (99.9999%#) with an 837, 1-ield was discussed (73E). The material is refined in a plastic tube wound around a glass cylinder with a heater above it. The rotating cylinder results in an endless number of multiple zones traversing the material. kfonocrystals of BaTiOa were produced by a zone recrystallization technique (72E). T h e addition of PbTiOs resulted in almost transparent samples. The heat requirements for the zone refining of molybdenum were discussed (.3E). The following equation was found to describe the heat requirements: P = Ad Bd2
+
ivhere
P
= power required to melt the
rod d = diameter of the rod
.4 is proportional to the 4th power of the absolute melting point B is proportional to the thermal conductivity near the melting point A combination of three zone refiners was used to purify organic materials (4E). T h e following types of compounds were successfully refined : amines, quinones, aromatic hydrocarbons, alcohols, and phenols. Refractory materials were zone melted (5E, 6 E ) . I n the latter report, an electron-bombardment floatinq-zone furnace was described. Refining of semiconductors (IUE, 77E),Si14 (I,?), tin (El?), and boron (7E) were the subjects of recent studies and patents.
Chicago Bridge & Iron Co
INDUSTRIAL AND ENGINEERING CHEMISTRY
U
(W
(7F)
(30
Sketch of Hortontype crystallizer
Courtesy,
Table 111.
Material Grown
.A detailed study of the repartition coefficients of certain impurities in zinc was made (ZE). Large departures from theory c\.ere observed because of slow diffusion in the liquid phase, as \vel1 as irregular crytallization velocity.
Single Crystals T h e literature pertaining to single crystals continues to expand. I n addition to those reports listed below, Table I11 cites further studies in this area. Pure single crystals of BaTiO; \vere grown from a mixture of BaC12, BaC03, and T i 0 2 (ZFj. Barium oxide single crystals \\'ere grown at 500" to 550' C. and atmospheric pressure by heating Ba(0H)z in dry hydrogen ( 7 2 7 ) . T h e higher melting metals, such as copper, Lvere grown as single crystals using a split graphite mold under high vacuum ( 7 F ) . Pure germanium and silicon crystals were prepared by the Czochralski method ( 5 F ) . Germanium-silicon alloys w.ith equal electrical resistance throughout the crystal were reported ( 4 F ) . Very slob\cooling was used to achieve this. A patent was granted for a method of growing single quartz crystals ( 7 7 F ) . More usable material for making crystal plates is obtained by proper control of the seed size, shape, and orientation. Equipment Equipment for the fractional crystallization of hydrocarbons was described in two recent patents (5G, 73G). I n the first, a porous piston forces the crystals through a heated zone containing a molten fraction. In the second, a refrigeration system crystallizes out impurities. -4nother patent (78G) describes the continuous fractional crystallization of 0- and p-dichlorobenzene. Partial melting and use of a cold refrigerant in direct contact with the feed serves as a basis for a countercurrent fractional crystallization scheme (72G). Patents \ v e x also granted for fractional crystallizers (70G, 77G). A wetted-wall column was used as an evaporative crystallizer (7G). A high velocity gas stream disintegrates the feed stream, spreading it around the inside of the column. Capacity of the equipment and possible applications are given. -4centrifugal crystallizer was described (8G) in which an immiscible liquid, with a density equal to that of the crystals
an and greater than that of the mother liquor, is used. The crystal suspension with the inert liquid is withdrawn a t the periphery. and the mother liquor is withdrawn at the center of the centrifuge. A detailed discussion of a draft tubebaffle (D‘l-B) crystallizer \vas given in a recent study (SG). Potassium chloride crystals groivn in a three-stage continuous vacuum crystallizer and a DTB crystallizer xvere comparrd ; improved size and uniformity were obtained in the latter. Large crystals were obtained by control of fines concentration (716)and were favored in a n annular-type crystallizer (75G). T h e purification of 2methyl-5-vinylpyridine was obtained a t higher throughput rates by means of a rapidlp pulsating pressure of 15 to 200 cycles p f r minute (76G). Equipment \vas described for groiving large monocrystals of S H , H , P O , ( J G ) : quartz (6s). heat-resistant materials in a vacuum (Z),and CdS (77G). Relarively large crystals of substances Iritli a low growth rate irere produced in the equipment described (7G). [$-axlike crystals arc produced and purified in a crystallizer described in a parent (3G).
Industrial Practice Fractional cr)-stallizatiun of Searls Lake brine and sea water \vas achieved by the addition of ethyl alcohol ( 7 7 H ) . About 90% of the strontium and 70% of the calcium are precipitated from sea water by the addition of 20% ethyl alcohol. This technique \vas suggested to recover by-producrs in the production of potable water from sea lvater. .4 parent was issued ( 3 H ) describing the fractional crystallization of alkylbenzenes. Needlelike crystals are avoided b\- control of turbulence during various stages of the process. Partial melting of crystals and countercurrent movement of a compact mass of crystals displace mother liquor and impurities ( 7 4 H ) . High product yield is obtained, as the high-melting component of the reflux stream freezes preferentially as it comes in contact with the cold crystal mass, From a mixture of m-. p-j and o-xylenes, p-xylene is obtained by partial melting of a slurry, filtration, compression, and !vashing ivith a n organic solvent (72H). Pilot plant production of hydrothermal synthetic quartz \vas described (70Hj. Grojrth rates of 60 mils per d a y \yere obtained under optimum conditions. .4dvantages and disavantages of bench scale pilot plant units \vere discussed (QH). Simulation of critical control conditions \vas found to be the major factor in design of pilot plant units. Purification and crystallization of ureais described in a recent patent (77H). Potassium sulfate from sea bitterns (7H), RIgSOl ( 6 H ) , SaCI. N a 2 S 0 4 and Na2C03 from Sambhar bitterns (75H),
v d
Unit Operations Review
fected by the presence of (NHI),CO,, NH4HC03, NaCI, and SH3 ( 7 4 . 4 . I n seeded systems the McCabe AL laiv \vas found to be valid. Surfactants \vert: found to retard the grobvth of individual faces of adipic acid (73.3). .4 greater retarding effect !vas observvd with very small crystals than Lvith larger ones. Inhibition of nucleation of supercooled \rarer by 4 g I \vas achieved by means of alcohols and amines ( 7 . V ) . \’arious additives \rere used to study the modifications of C u S O I . 2 H n O groxzn from aqueous solutions ( 7OJ). C:omple.rforming additiL-es influrnced the amount of impurity incorporated in grotring crystals (84.Distribution of impurities could be controlled in this manner. Dislocations in T i F may come about by inclusions (5.3). Additional studies relating TO the effect of impurities and additivcs on crystal gro\\-th are given in Table 11..
Table IV. Courtesy: Struthers Wells Corp.
Ammonium sulfate crystallizer i s 20 feet in diameter and 95 feet high
and the productionofHaPO4 by the hemihydrate process (73H) are described in recent reports. Methods of manufacture of S a C l from sea water and deposits in southern France were described (4H). JVater-insoluble organic crystals were purified by means of a suitable emulsifying agent lvhich creates a n emulsion of the mother liquor in the water phase (5H).Higher purities and greater yield of cyclohexane were obtained by this method as opposed to conventional methods. Controlled melting (76H) and stagewise separation ( 2 H ) improved the purity of crystallizable hydrocarbons. Coarse crystals of S a H C O , \rere obtaincd in a three-stage carbonation Pure 1-inch-thick titanium process (6”). crystals were produced from the system Sa-’Ti-C1 a t 850’ C. ( 7 H ) .
Impurities and Additives Tivo recent studies (77.3, 72.4 discussed a t length the effect of agitation on the purity of crystals. I n a CuS04FeSO4-H?SO4 system agitation increased the FeSO? content in C u S 0 4 stals by about 25% at compared with stals grown under quiescent conditions. T h e rate of stirring also affected the occlusion of iso- and isodimorphic impuriiies in crystals. Here stirring also increased occlusion. T h e adsorption of foreign ions was found to occur a t the surfaces of the mosaic building blocks of salt crystals (7.3). T h e shape and size distribution of N t l l C l crystals were found to be af-
Impurities and Additives
.Ldrlitive
Cr? *tal
KBr NaCl Co(OH)? NHrN03
Phenol Polyelectrolytes
so*--
Eosin and other dyes Urea
Rare earth oxalates
Sod--
Zn
Surf actant s Glycoside ester Electrolytes
Sugar
Ref. (SJ)
(,?A
(4J ) (1SJ) I 1 o’J)
(GJ) (7.J) WJ) 117.1)
literature Cited Reviews and Books (1.4) Bassett, G. .I., Menter. J. \V., Pashley. D. \V.$ Structure Properties Thin Films, Proc. Intern. Conf.. Bolton Landing. N. Y.>p. 11 (1959). (2.4) Figurovskii, N. A.. Komarova. T. .L, 2liur. iVeorg. Khim. 4, 522 (1959). (3A) Garrett, D. E., Brit. Chmi. E q . 4, 673 (1959). (4‘4) Harrison, F. W., Restarch (London) 12, 395 (1959). (5.4) Holden, A,. Singer: P.. “Crystals 63
Crystal Growing.” .4nchor Books, Garden City. N. Y.. 1960. (6A) Novosil’tsev. N. S.. others. A’ri~tniiop r a f y a 4 , No. 1: 101 (1959). (7‘4) ,Parr, N. L.? “Zone Refinin? and Allied Techniques,” George Newncs, Ltd., London, 1960. (8.4) Shubnikov. .4. V.. Sheftal, N. N., eds.. “Growth of Crystals,” Vol. 11, Consultants Bureau, Inc.. S e w York, 1959. (9A) Svanoe, H., Chon. Enz. Prour. 5 5 , No. 5. 47 (1959). (10.4) Van Hook, A,: 2nd. saccnr. i d . 51, 227 (1958). (1 1A) Zagrodski. S.: Il’iadomoiri Chemi. 13, 185 (1953).
Nucleation (1B) Akhumov. E. I.; Pl-lkova. I-. V., Freiberger Forxhungsh. A123, 251 (1 959). (2B) Avgustinik, .4. I.. Srlikat Trrh. 10, 58? (1959). (3B) Cahn, J. \V., Hilliard, J. E.. J . ChPm. Phys. 31, 688 (1959). VOL. 53, NO. 2
FEBRUARY 1961
157
an
r dUnit Operations Review
(4B) Cutler, I. B., Kinet. High-Temp. Processes Conf., Dedham, Mass., 1958, p. 120 (1959). (5B) Fletcher, N. H., J . Chem. Phys. 30, 1476 (1959). (6B) Ibid., 31, 1136 (1959). (7B) Gyulai, Z., Acta Phys. Acad. Sci. Hung. 10. 371 (1959). (8B) ’Higu‘chi; W. .I. G
Mic. 59-5978; Diisskrtation Abstr. 20, 2390 (1960). (11B) Kolthoff, I. M., van’t Riet, B., J . Phvs. Chem. 63. 817 11959). (12B) Mikhnevich,’ G. ‘L., kolloid Zhur. 21, 69 (1959). (13B) Ibid., p. 325. (14B) Neels, H., Freiberger Forschungsh. A123, 405 (1959). (15B) Sears, G. FV., J . Chem. Phys. 31, 157 (1959). (16B) White, M. L., Frost, A. A., J . Colloid Sci. 14, 247 (1959). Crystal Growth (1C) Anikin, I. N., Zapiski Vsesoyuz. Afineral. Obshchestaa 88, 196 (1959). (2C) Baker, R. G., Branion, D. G., Nutting, J., Phil. Mag. [8]4,1339 (1959). (3C) Bennett, A. I., Longini, R. L., Phys. Rev. 116, 53 (1959). (4C) Buckser, S., Tung, L. H., J . Phys. Chem. 63, 763 (1959). (5C) Cartier, R. M , Pindzola, D., Bruins, P. F., IND.ENG.CHEM.51, 1409 (1959). (6C) Costa, A. C. S., Menezes Silva Selling, R., Anais assoc. brasil. quim. 18, 1 (1959). (7C) DdVries, R. C., J . Am. Ceram. SOC. 42, 547 (1959). (8C) Domokos, G., Malicsko, L., Acta P h u . dcad. Sci. Hung. 10, 185 (1959). (9C) Evraud, C., Lanaspeze, P., Comfit. rend. 248, 2592 (1959). (10C) Ham, F. S., J . Appl. Phys. 30, 1518 (1959). (11C) Heath, W. S., L‘niu. Microfilms (.inn Arbor. Mich.). L. C. Card NO. hit. 58-2302; Di&rtation Abstr. 19, 2557 (1959). (12C) Hillig, W. B., Kinet. High-Temp. Processes Conf., Dedham, Mass., 1958, p. 127 (1959). (13C) Hillig, W. B., Strong, R . M., J . Phys. Chem. 63,1012 (1959). (14C) Noring, I. M., Schlichtkrull, J., Danish Patent 87,001 (March 9, 1959). Vapor Phase Growth (1D) Ambroz, J., Ambroz, L., Dvorak, S., Chern. prdmysl 10, 23 (1960). (2D) Bassett, G. A,, Pashley, D. W., J . Inst. Metals 87. 449 (1959). (3D) Boer, K . W., hmmerman, K., Monatsber. deut. Akad. Wzss. Berlin 1, 336 (1959). (4D) Chang, Y. L., Scz. Sznica (Peking) 8, 629 (1959). (5D) DeVries, R. C., Sears, G. W., J . Chem. Phys. 31, 1256 (1959). (6D) Dittmar, W., Neuman, K., 2. Elektrochem. 63, 737 (1959). (7D) Henry, J. L., Dreisbach, S. H., J . Am. Chem. SOC.81, 5274 (1959). (8D) Ibuki, S., J . Phys. SOC. Japan 14, 1181 (1959). (9D) Kremheller, A , J . Electrochem. SOC. 107, 422 (1960). Z o n e Melting (1E) Baba, H., Tadashi, N., Araki, H., Bull. Chem. SOC.Japan 32, 537 (1959). (2E) Baralis, G., Fabbrovich, L., Met. ttal. 52, No. 2, 63 (1960).
1 58
(3E) Belk, J. A.: J . Less-Common .lfetals 1, 50 (1959). (4E) Beynon, J. H., Saunders, R . A., Brit. J . Appl. Phys. 11, 128 (1960). (5E) Davis, M., Lever, R. F., Brit. Patent 826,132 (Dec. 31, 1959). (6E) Geach, G. A , , Jones, F. O., J . LessCommon Metals 1, 56 (1959). (7E) Greiner, E. S., J . Appi. Pips. 30, 598 (1959). (8E) Ivannikov, A. S., others. Russ. Patent 118,981 (March 25, 1959). (9E) Jenny, D. A., Jensen, R. V., U. S. Patent 2,902,350 (Sept. 1, 1959). (10E) Jensen, R . V., Zbid., 2,898,249 (Aug. 4, 1959). (11E) Kanbayashi, K., Japan Patent 3204(’59\ (Ami1 30). (12E) KramArAv, 0’. P., KristallograJya 4, 109 (1959). (13E) Liu, M-C.. Wu Li Hsueh Pa0 15, 787 (1959). (14E) Pfann, W. G., U. S. Patent 2,904,41; (Sept. 15, 1959) 15E) Ibid., 2,926,075 (Feb. 23, 1960). 16E Zbid., 2,932,562 (April 12, 1960). 17E Richards, J. L., J . Appl. Phys. 31, 600 (1960). Single Crystals
(1F) Andrade, E. N. d a C.. Nature 186, 540 (1960). (2F) Arend, H . T., Czech. Patent 91,151 (July 15, 1959). f3F) Ascoli. A , . Odescalchi. U.. Schiavini. G. M., Entrzia nucleare (Milan) 6 , 781 (1959). (4F) Kekua, M. G., Petrov, D. A , , Suchkova, A. D.: Izurst. Akad. .l’auk S.S.S.R., Otdel. Tekh. h’uuk, 21tt. i Toplivo No. 1, 9 (1959). 5F) Bumm, H., Vide 14, 300 (1959). utuzov, V. P., Russ. Patent 117,452 (Feb. 6, 1959). (7F1 Calais, D., Lacombe. P.. Simenrl, h.,Me‘m. sci. rev. mit. 46, 261 (1959). (8F) Elbinger, G., Exptl.. Tech: Phssik. 7, No. 5. 193 (1959). (9F) Geil, P. H., Jr., Symons, N. K . J., Scott, R. G., J . Appl. Phys. 30, 1516 (1959). (10F) Geiselman, D., Guy, A. G., Trans. Am. Inst. Mining, Met., Petrol. Engrs. 215. ---,814 (1959) (11F) Jaffe: H.,’ Turobinski, J., U. S. Patent 2,923,605 (Feb. 2, 1960). (12F) Lynch, R. T., Lander, J. J., J . Appl. Phys. 30, 1614 (1959). Apparatus a n d Equipment (1G) Chandler, J. L., Brit. Chem. En:. 4, 83 (1959). (2G) Dobrovenskii, V. V., Pribory i Tekh. Ekspt. No. 5, 134 (1959). (3G) Findlay, R . A , , U. S. Patent 2,898,271 (Aug. 4, 1959). (4G) George, H . J. C., Ibid., 2,929,692
&March 22, 1960). (5 \ Green, R . M., Zbid... 2.921.968 , , ’ (Jan. 19, ’1960). (6G) Kohman, G. T., Ibid., 2,895,812 (July 21> 1939). (7G) Kopek, L., Brit. Patent 815,791 (July 1, 1959). (8G) Loy, J. W., U. S. Patent 2,921,969 (Jan. 19, 1960). (9G) Newman, H . H., Bennett. R. C., Chern. Eng. Proqr. 5 5 , No. 3, 65 (1959). (1OG) Ratje, J. D., U . S. Patent 2,919,991 (Jan. 5, 1960). (11G) Reynolds, D. C., Czyzak, S. J., Zbid., 2,907,643 (Oct. 6, 1959). (12G) Rush, E. E., Ibid., 2,890,938 (June 16, 1959). (13G) Ibid., 2,910,516 (Oct. 27, 1959). (14G) Saeman, W. C., Zbid., 2,883,273 (April 21, 1959).
INDUSTRIAL AND ENGINEERING CHEMISTRY
(15G) Schneider, C.: Brit. Patent 815,008 (June 17, 1959). (16G) Stallings, P. S., Jr., U. S. Patent 2,913,344 (Nov. 17. 3959). (17G) Weedman, J. A.. Ibid.: 2,903,343 (Sept. 8: 1959). (18G) Wiegandt, H. F., Ibid.. 2,912,469 (Nov. 10, 1959). Industrial Practice
(1H) Bhavnagary, H. M.. Gadre, G. T., Research Ind. (.Vew Delhi) 4, 84 (1959). (2H) Bozich, S., Lewis, E. W., Smith, B. D., U. S. Patent 2,913,503 (Nov. 17, 1959). (3H) Buell, C. K.: ibid., 2,881,230 (April 7. 1959). (4H) Chirruy, P., Bull. sac. sci. .lrancy 18, 138 (1959). ( j H ) Chuffart, R . C.. Brit. Pat. 797,369 (July 2, 1958). (6H) Davidenko, N. E;.. Konipleks. Ispol’zouante Solyanykh Resursoi, Stvasha z Perekobskikh O m . Akad. .Vauk CTkr. ,P.S R. 1958, p, 137.’ (7H) Dean, R . S., L.S. Patent 2,909,472 (Oct. 20: 1959). (8H) Dow Chemical Co., Brit. Patent 811.053 (March 25. 1959). (9H) Garritt, D. E., Chth~.Eng. P70qY. 5 5 , No. 9, 44 (1959). (10H) Laudise, R . A., Sullivan. R . X., [bid., 5 5 , No. 5, 55 (1959). (11H) Matile, P., L.S. Patent 2,892,870 (June 30, 1959). (12H) McBride, J. -4.: Green, R. M., Itid., 2,904,412 (Sept. 15, 1959). (13H) Peet. R. B., Ibid., 2,885,264 (May 5 , 1ncn, 17JY).
(14H) Quigg, D. J., ibid., 2,890,239 (June 9, 1959). (15H) Sapre, R. K., Baxi, D. R.. J . Sci. Ind. Research (india) 18A, 430 (1959). (16H) Tarr, T. A , , E. S. Patent 2,885,431 (May 5, 1959). (17H) Thompson, A. R., Blecharczyk, S. S.,Rhode Island Univ., Eng. Expt. Sta., Leaflet No. 2 (1959). Impurities a n d Additives (1J) Balarev, D., Frei6erger Forschungsh. A123, 333 (1959). (25) Barber, E. A , , Brit. Pat. 822,893
(Nov. 4, 1959). (35) Bliznakov, G., Kirkova, E., Kotseva, E., Compt. rend. mad. bulgare sci. 12, 121 (1959). (4J) Diamond Alkali, Brit. Patent 811,468 (.4pril 8, 1959). (55) Gilman, .J. J., J . .4ppl. Phys. 30, 1584 (1959). (6J) Glasner, A , , Steinberg, M., Levy, E., Chemist Analyst 48, 37 (1 959). (74 Gorbunova, K. M., Lebedeva, K . P., Zhur. Fir. Khim. 33, 669 (1959). (8J) Gorshtein, G. I., Radiokhimzya 1, 497 (1959). (9J) Kknt, S, E., L. S. Patent 2,871,148 (Jan. 27, 1959). (1OJ) Kleber, W., Steinike-Hartung, U., Z . Krist. 111, 213 (1959). (11J) Matusevich, L. M., Tsvetnye Metal. 32, No. 11. 37 (1959). (125) Matusevich, L. M., Zhur. Prikiad. Khim. 33, 316 (1960). (13J) Michaels, A. S.,Colville, A. R . , J . Phys. Chem. 64, 13 (1960). (145) Moriyama, T., Asahi Garasu KenkyG HGkoku 9, 66 (1959). (155) Poppoff, I. G., Sharp, G. W., J . Meteorol. 16, 288 (1959). (16J) Rozman, B. Yu., Bordkina, L. I., Russ. Patent 117,370 (Feb. 6, 1959). (175) Schneider, F., Emerich, A., Jorn, K., Zuker 12, 118 (1959). (185) West, D. H., Pincott, J., Brit. Patent 812,476 (April 29, 1959).
