The early history of crystallization

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THE EARLY HISTORY OF CRYSTALLIZATION HERBERT M. SCHOEN, C. S. GROVE, JR., and JOSEPH A. PALERMO1 Syracuse University, Syracuse, New York

INTRODUCTION

John H. Perry2once raised the question, "Of what use would a knowledge of the past practices and achievements and detailed historical survey of chemical engineering be?" Perry questioned whether such a study would only provide interesting or light reading and whether the reader would get a "return on his investment" that was "attractive" in relation to the time and effort spent in such pursuits. Details of past discoveries may not be of direct value to the specialists in a given field, but it is unquestionable that if all prior developments had been more widely known progress would have been more rapid. A knowledge of the history of the chemical profession, for example, most certainly serves as a guide and stimulant to the imaginative professional person. The physician relies on clinical records, the lawyer on legal precedent, the militarist, astronomer, and mathematician all rely to a varying extent on historical records-why then should not the chemical engineer or chemist do likewise? NATURAL CRYSTALLIZATION PROCESSES

The art of crystallization extends back in history as far as the writings of man. Since the natural processes were, of course, the first known instances of crystallization phenomena it is impossible to determine with any exactness when these processes first became mandirected. With the exception of evaporation, the oldest chemical engineerng unit operation is undoubtedly that of crystallization, because in many instances crystallization is the direct result of evaporation. The evaporation of naturally occurring solutions, such as sea water and natural brines, is generally considered to be the oldest unit operation; it is inevitable that crystals were formed, intentionally or unintentionally, in such processes.

resulting brine is then evaporated over a fire until the salt crystals start to separate from the liquid. According to C a l d ~ e l l"an , ~ old Chinese print of 2700 B.C. shows the use of artificial evaporation and crystallization in the production of salt. At some unrecorded date, the device of introducing twigs or strings into the mother-liquor to collect the crystals and hold them off the bottom, was introduced, as has been shown by Agricola (1556). In any event, these early crystallization methods made use of shallow open tanks, air cooling of the surface, and batch operation." We are indebted to Pliny's "Naturalis Historia" for records of some of the early efforts and practices of mancontrolled brine evaporation and salt crystallization processes. He states that salt was secured in various, but closely related, methods in the civilization centers of his time. Of artificial salt there are several kinds; the common salt, and the most abundant, being made from sea-water drained into saltpans, and accompanied by streams of fresh water; but it is rain more oartieularlv. and above all thines. the sun. that aids in its formakon; indeed without the last ?$ would never d r y . . I n Crete, however, salt is made without the aid of fresh water, and merely by introducing seewater into the salt-pans. On the shores of Egypt, salt is formed by the overflow of the sea upon the land, already prepared for its reception, in my opinion, by the emnations of the river Nilos. It is made here also from the water of certain wells, discharged into salt pans. . ..In Cappadoria, also, both well and spring water are introduced into the salt oms. In Chaonia. there is a. sorine. from the waters of a

CALDWELL, H. B., Chem. & Mel. Eng., 42,213 (1935).

BEGINNINGS OF MAN-DIRECTED CRYSTALLIZATION

Man has used salt in his food since the earliest recorded history, and while a great deal of such salt was obtained from natural salt deposits, a very large amount was obtained, even in the very early days, by an artificial crystallization operation. Even today in very cold climates such as in the region of the White Sea in Siberia, common salt is still manufactured by first concentrating sea water by the removal of part of the water by freezinn. After two crom of ice have been removed, the

' Present address: Colgate Prtlmolive Company, Jersey City, New Jersey. a PERRY, J. H., Chem. & Met. Eng., 4 2 , 196 (1935). 3 j13

S o l u Evaporation on the River Nile.

Woodcut from GeorwZus Agricola's "De re metallisa" (1556)

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JOURNAL OF CHElMICAL EDUCATION

first crystallized by householders who evaporated the juice for making preserves. The sweet crystals that separated out gave the early people of India their first ideas of sugar making. In 55 B.c., a t the time of the invasion, Julius Caesar stated that the inhabitants of Cheshire, England, manufactured common salt by pouring brine over charcoal faggots and scraping off the crust as it formed. During this first invasion period, the Romans taught the English the open-pan process of evaporating brine and producing salt. At the beginning of the seventh century Isodorus stated that the evaporation of sea water and the crystallization of salt from the resulting brine by means of solar evaporation of sea water and the crystallization of salt from the resulting brine by means of solar evaporation was known and practiced extensively a t that time. The Arabian, Avicenna (98&1037), in his hook "Cannon of Medicine" writes of the solidification of aaueous solutions. not by cold alone, on the contrary b; the action of dryness, which converts the waterineis to earthiness. Some 400 years later Birringuccio, in his "Pirotechnia." wrote in meat detail on the nature of saltoeter and the' method foilowed in making it. A furnace is made with one or two large copper kettles like those used in dyeing, bricked in a t the top. These are filled two-thirds full with the saltpetery water as saturated as possible. I t is boiled very slowly until it is reduced to about a third. Then i t is removed and put to sett,le in a large covered vat . . . when the water has settled and is very clear, an earthy thick sediment, that it contained is removed. and it is out to boil aeain . . until the fine watery parts evaporate and the salt petery parts became so thick that the water congeal8 when taken out and put in chests or v& to cool . . . having tested this water and seen that it is reduced to the point where i t congeals, take it out and put it in vessels of wood or rough ones of earthenware that are crossed inside with same sticks of wood for congealing on. Let it cool and rest well for three or four days.

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cr7rt.11iration Equipment fro," Didera, pnd D'Alemh.rt's Ensydopedie, "Ou Distionnaire Raieonne des Sciences. des Artea, dea Matiom. par u n Sosieto de Gons de Lettros" Paris. 1752801

which, when boiled and left to cool, there is an inert salt obtained, not so white as ordinary salt.

In Egypt, according to the "Papyrus Ebers" (about 1500 B.c.) the solar evaporation and crystallization of sea water that has been allowed to flow into enclosed basins a t the sea shore was carried out. It mas not until sometime after 327 B.C. that sugar-cane juice was -,-

Although the language is somewhat strange to us, the tools and techniques bear close resemblance to some of our present-day methods. The importance of salt to man was evidenced by Paracelcus; he states that "God has driven man to such a pitch of necessity and want that he is unable to live in any way without salt, but has most urgent need thereof for his food and eatables." The great importance of salt was also recorded in the words of Agricola in his "De re Metallica": The history of salt making in salt pans, from sen water or salt springs goes further hack than human records. From an h i s torical point of view the real interest attached to salt lies in the hewing which loedities rich in either natural salt or salt springs, have had upon the human race. Many ancient trade routes have been due to them, and innumerable battles have been fought for their possession. Salt has, a t times, served far currency and during many centurie~in nearly every country has served as a basis for taxation.

Pitolo courtesy

H.Amnro

[Snl Tslo L d n . Lisbon. Portouall

The Anoiont Art of Salt Production by Solar Evaporation, aa Practised in Portugal Today

Although this brief account of the early efforts of man in the art of crystallization does not reveal to us anything of practical value regarding processes of today, it lays the groundwork upon which the modern-day practices are built. If nothing else it creates in us a feeling

VOLUME 33, NO. 8, AUGUST, 1956

for the antiguity of the art and perhaps gives us some insight into the extent and importance of crystallization on man in earlier times.

I n the seventeenth century Anton Van Leeuwenhoek studied with the microscope a very large number of crystalline materials and also studied their formation and growth. At this early period of technical and LATER DEVELOPMENTS IN THE ART scientific knowledge it is interesting to note that he The history of crystallization is closely interwoven believed, by analogy, that the cubic crystals of salt with the study of the crystals themselves. It was were composed of minute cubic crystals, and these in through a familiarization of crystals, their forms, and turn were composed of still smaller ones. nature that man was able to apply his knowledge to a M. A. Cappellers' "Prodromus Crystallographiae" practical end and develop more satisfactory processes for written in 1723 was the earliest treatise on crystallogproducing them. I t is with this thought in mind that raphy. A few years later, C. Linnaeus described we feel the necessity of reporting on some of the about 40 common forms of crystals among minerals in pertinent advances in both of these closely related "Systema Naturae." No real advances were made in the field until the end of the eighteenth century fields. Any attempt t o subdivide the history of these fields when J. B. L. Rome de I'Lisle and Hauy published their into chronological divisions is, of course, quite arbitrary. works. We may say, however, that the first important step in It was the work of Rome de I'Lisle and Hauy's law of the study of crystals was that of Nicholas Steno. rational indicies that laid the foundations of crystallogSteno, a famous Dutch physician and afterwards a raphy. It is a t the end of the eighteenth century and Bishop of Titiopolis, gave in his treatise "De Solido the beginning of the nineteenth that we begin to see a Intra Solidum Naturaliter Conterito" (1669) his transition from the art to the science. Although we ohsewations on quartz crystals. L. J. Spencer, of must remember that, even today the transition is not the British Museum, states in the Encyclopedia Brit- complete. Many of the theories that have been detanka, "He [Steno] found that although the faces of veloped have yet to find their fullest application in different crystals vary considerably in shape and modern-day crystallization technology. relative size, yet the angles between similar pairs of faces are always the same. He further pointed out that the crystals must have grown in a liquid by theadditions of layers of material upon the faces of nucleus . . . . The thickness of the layers, though the same over each face was not necessarily the same on different faces, but depended on the position of the faces with respect to the surrounding liquid; hence the faces of the crystal, though variable in shape of size, remained parallel to those of the nucleus, and the angles between constant." We now know this as the first law of crystallography. At about the same time, Robert Boyle in his "Origins of Forms and Qualities" noted that the habit of a crystal may be altered when formed in a liquid that contains other salts in solution, thereby laying the groundwork for "crystallization-additives" or "habit modification." He stated that "Not withstanding the regular and exquisite figures of some salts, they may, by the addition of other bodies, he brought to cou- Cm.talliration b y Evaporation. Woodcut from Georgiva Agrisol... stitute crystals of very different yet curious shapes." "De re motallism" (1SS6)

THIRD LIGNlN ROUND TABLE AT THE INSTITUTE OF PAPER CHEMISTRY TEE Fundamental Researoh Committee of the Technical Asso&tion of the Pulp and Psper Industry and the Committee on the Chemistry of Plant Products of the National Research Council are jointly sponsoring the Third Lignin Round Table at The Institute of Paper Chemistry, Apple ton, Wisconsin, September 24, 25, and 26, 1956. The subject of the Round Table will be "The Biochemistry of Lignin" with emphasis on the formtion of lignin. The program chairman is Dr. Roland E. Kremers of The Institute of Paper Chemistr.", a member of the National Research Council Committee. Questions dealing with registration, accommodations, transportation, ete., ~houldbe directed to Dr. Harry F. Lewis, Chairman of the Fundamental Research Committee of TAPPI and Vice-president of The Institute of Paper Chemistry.