Lost Discoveries: The Ancient Roots of Modern Science-- from the Babylonians to the Maya

Read an Excerpt

from Chapter Three

Astronomy: Sky Watchers and More

China

Chinese astronomy resembles most other premodern sky technologies in that it was driven by divination. Yet Chinese astronomy differed from all others. It was run solely by a government bureaucracy and based on a worldview that said the ruler was "emperor under all heaven" — a divine appointment. Yet the connection between celestial events and human fate was perhaps even more profound. The link was not just between heavenly deities and the emperor; the earth, the emperor, and the entire cosmos were bound together in one gigantic entity, a superorganism in which the five elements, or "phases" — fire, air, wood, earth, and water — were in constant interaction as they sought their affinities with one another.

Yet in China as elsewhere, portent astrology called for careful and regular observations of celestial events. The cosmic importance of every omen in the sky demanded that its results be noted down in detail. As a consequence, the Chinese possess the longest unbroken run of astronomical records in the world, observations of considerable importance to modern astronomers, whose research requires data about long-term celestial events.

China developed astronomy very early in its history. Evidence goes back five thousand years. The ancients wrote stars-laden texts in many forms — on wine jugs, tortoise shells, and silk. The earliest records from archaeological sites in Qinghai Province consist of ceramic fragments on which are painted images of rayed sun disks and moon crescents. A piece of bone found to be thirty-five hundred years old contains writing showing that the Chinese already knew the length of the year to be 3651—4 days. There is evidence of star observation from before the twenty-first century B.C.186

The first recorded astronomical inscriptions date from the sixteenth to nineteenth centuries B.C. in the Shang kingdom of Henan Province. These artifacts are examples of an astronomical-divination system, technically called scapulimancy, a technique going back to Neolithic times. Selecting an ox or deer shoulder blade (scapula) or a tortoise shell, the diviners then dried, polished, and drilled the material with holes. They inserted a hot metal brand into one hole and examined the pattern of resulting cracks in the bone or shell. The diviner noted both the prognostication and later results on the cracked material.

The oracle bones' existence was lost to the modern world until 1899, when a scholar from Peking became ill and sent his valet to a drugshop for medicines. One ingredient in the potion the pharmacist sent him was labeled "dragon's bones." The scholar realized it was bone chips with words inscribed on them in ancient Chinese — oracle bones.

During the following decades the bones were traced to a field near An-yang, around three hundred miles southwest of Beijing. During the 1920s and '30s, some twenty-five thousand oracle bones were excavated there, from what may have been a palace archive. At least 135,000 more pieces have been excavated since, forming a treasury of information going back to Shang times. This vast library recorded on the bone texts has enabled modern historians of astronomy to backtrack regularly occurring celestial events with computers to match sky phenomena inscribed millennia ago.

Recently, NASA astronomers used fourteenth-century B.C. oracle bones to help determine how much the earth's rotation is slowing down. Based on analysis of the tortoiseshell inscriptions, Kevin Pang and his colleagues at the Jet Propulsion Laboratory at Pasadena reported they had fixed the exact date and path of a solar eclipse seen in China in 1302 B.C. That, in turn, led them to calculate that the length of each day was 47Ž1,000 of a second shorter in 1302 B.C. than it is today.

A cache of five thousand pieces of oracle bones excavated in An-yang in 1972 yielded a series of divinations of sky events. The Chinese astronomical historian Zhang Peiyu found that six dates recorded in the inscriptions matched perfectly with a series of solar eclipses visible from the Henan area in the twelfth century B.C., half a millennium earlier than records of such events obtained from Babylonia or Egypt. Other Shang bones yielded inscriptions of lunar eclipses.

A reconstruction of another bone recording from around the same time revealed the observation of a supernova. The supernova inscription, perhaps the most ancient extant record of a nova sighting, says, in part, "On the seventh day of the month...a great new star appeared in company with Antares." The Chinese called these supernovas "guest stars." Thus the Chinese knew well what they were observing when, in June 1054 (A.D.), a star in the constellation Taurus blew. Chinese sky watchers reported it to be as bright as Venus, apparent during daylight, and visible for twenty-three days. The remnant of this explosion can be seen today and is called the Crab Nebula. (The Greeks have no record of the supernova.) Experts today have compiled detailed descriptions of supernova explosions that coincide with contemporary X-ray and radio sources.

In the Greek-influenced West, the sun and heavens were supposed to be immaculate. But Chinese astronomers saw spots on the sun. The earliest surviving record of a sunspot observation is by the astronomer Kan Te in the fourth century B.C. Kan Te assumed that these spots were eclipses that began at the center of the sun and spread outward. Although he was wrong, he recognized the spots for what they were — solar phenomena.

The next documentation of sunspots was in 165 B.C., when it was reported the Chinese character wang appeared in the sun — shaped like a cross with a bar across the top and bottom. It is accepted as the world's earliest precisely dated sunspot. The West's earliest reference to sunspots is Einhard's Life of Charlemagne, around A.D. 807. Joseph Needham found 112 instances of sunspots recorded in Chinese histories between 28 B.C. and A.D. 1638. In other Chinese books he found hundreds more notices, "but no one has had time or stamina to collect them into a body," comments sinologist Robert Temple. Nonetheless, the sunspot records constitute the oldest continuous series of such observations. And again, these are of great use to modern astronomers. Sunspot cycles, for instance, affect the earth's ionosphere and weather (magnetic storms are related to sunspots). Analyzing available records, Japanese astronomer Shigeru Kanda reports he has detected a 975-year sunspot cycle. If so, it may have significant implications for weather cycles.

The Chinese were also careful observers of comets. They computed the approximate orbits of about forty comet trajectories with such precision that many of their trajectories could be drawn on star charts simply from reading ancient texts. They were interested in the precise position and direction of the tail of each comet.

In the year 240 B.C., astronomers officially documented the appearance of a comet today known as Halley's. Another comet recorded in 467 B.C. is also thought to be Halley's. In the 600s A.D., they observed that comets shine by reflected light like the moon. They noted that comet tails always pointed away from the sun, suggesting this phenomenon was the result of a solar "energy." Today it's known that this cometic tail direction is caused by the force of "solar wind," the sun's radiation. It wasn't much of a stretch, says Temple, for the Chinese to formulate the idea of solar wind. It is congenial with their cosmological assumptions, Chinese literature being filled with references to the ch'i of the sun's radiation. Ch'i, translated as something like the "emanative or radiative force," comes from the sun. To Chinese astronomers it would have been obvious that the sun's ch'i was strong enough to blow the tails of comets as if in a strong wind. The Chinese conceived of space as being full of strong forces.

As a consequence of the emperor's divine connection with the cosmos, it became traditional after important changes of rulership, and always after a switch to a new dynasty, for a fresh calendar to be drawn up. This custom was well established by Han times (206 B.C. to A.D. 220) and led to some forty new calendars made up between early Han and the beginning of the Ming dynasty in 1368.

According to the theory of monarchy, the ruling dynasty remained fit to rule because of the accord the emperor maintained with the heavenly order. His special status in the order of nature allowed him to maintain a parallel order in the political realm, for the state was a microcosm. If the emperor lacked virtue or was careless in his duties, disorderly phenomena would appear in the sky as a warning of potential political disaster. Thus astronomers had to incorporate as many phenomena as possible in a "correct" calendar. The calendar, issued in the emperor's name, became part of the trappings of power that demonstrated his dynasty's right to rule, a function, writes sinologist Nathan Sivin, "not entirely different from that of economic indicators in a modern nation."

The importance of astronomical observing in this world of extreme politics, then, made secrecy absolutely necessary. Because the data could be easily manipulated, it could be dangerous in the hands of someone trying to undermine the current dynasty. It was therefore state policy that the proper place to do astronomy was the imperial court. In certain periods it was illegal to do it elsewhere. With this information virtually classified as top secret, the astronomer became a high-level administrative functionary in a country that developed the most elaborate bureaucracy in the ancient world. The databases resided in a state observatory deep within the bowels of the palace.

If not the greatest astronomical mathematicians, the Chinese were the greatest star charters before the Renaissance. Their earliest star chart goes back to at least 2000 B.C., to a carving on a cliff at Jiangjunya in Jiangsu Province. The carving contains many stars, as well as human and animal heads. There are disks indicating the sun in seasonal positions and where a number of bright stars and the moon appear over the seasons. This bright region is recognizable as the Milky Way by its position and appearance; the Milky Way displays gaps and divisions that are depicted on the carving.

China, being in the Northern Hemisphere, fixed itself on the northern circumpolar stars, both for orientation and to express its concept of divine rulership. The circumpolar stars in the higher latitudes are raised quite high in the sky as they rotate about the pole, so the fixity of the polar axis became an apt metaphor for the divine right of emperors. The pivot point about which this rotation occurs is known as the north celestial pole. The emperors were clever to adopt the stars of the north, such as Cassiopeia and Cepheus. These stars are located near the celestial pole, so that in the temperate latitudes of most of China they are visible eternally in the sky, never hidden by the horizon.

The first catalogs of star positions appear to have been drawn up by Shi Shen, Gan De, and Wu Xian, the earliest notable astronomer in China, who worked between 370 and 270 B.C., two centuries before Hipparchus. Together their lists enumerated 1,464 stars grouped into 284 constellations. (The West made bigger groups, with only 88 constellations.) In A.D. 310, during the Western Chin dynasty (A.D. 265-317), this early work was collated by the astronomer royal Qian Luozhi, who cast a bronze celestial globe with the stars on it colored in red, black, and white to distinguish the listings of the three astronomers. As early as the Han dynasty, astronomers prepared star charts. Carvings and reliefs show individual constellations or asterisms depicted as dots or small circles connected by lines to delineate the constellation itself. This ball-and-link convention did not appear in the West until the late nineteenth century.

Star maps need a means of specifying positions of heavenly bodies with reference to one another. The science of mapmaking took a leap forward in the second century B.C. when Chang Heng invented what's now called quantitative cartography. Chang, the inventor of the seismograph and a leading scientist, applied a grid system to maps so that positions, distances, and itineraries could be calculated and analyzed. Chang Heng's own works are lost, although an official history of the Han dynasty stated, "He cast a network of coordinates about heaven and earth, and reckoned on the basis of it." Copies of these maps were never made, since the information on them was too dangerous to risk its falling into the wrong hands. Meanwhile, in Europe, mapmaking had degenerated under the influence of religion, says Robert Temple, "to a point scarcely credible."

Drawing actual charts of the sky means finding a way to depict positions as if one is drawing a map. Preparing maps also involves the problem of mapping the curved surface of the celestial sphere on a flat surface, just as mapping the near-spherical surface of the earth requires the use of map projection. This is made more difficult if the sky is seen as a dome curving above one's head. In both China and the West, projection goes back a long way for mapping the earth. But for mapping the stars, Chang Heng was first, drawing up in Han times a chart that was a "Mercator" projection.

Mercator projection was "invented" in Europe by the Flemish mathematician and geographer Gerhard Kremer, a.k.a. Gerardus Mercator, and first published in 1568. But this projection system had been used by the Chinese centuries before Mercator. The projection works by means of a cylinder. If one inserts a transparent globe of the earth (or other celestial sphere) in the center of a hollow cylinder and turns on a light inside the globe, the features of the sphere's surface will be thrown, or projected, onto this cylinder, and will reflect a certain distortion. The higher up and lower down from the sphere's center, or equator, the more the features are distorted. Virtually useless for land travel, this projection has the odd property that a navigational course drawn on it will come out as a straight line, whereas with other maps such courses are arcs.

The oldest surviving projection chart depicting the whole of the visible sky is painted on paper and now resides in the British Library. Dating from about A.D. 940, it comes from Dunhuang in Gansu Province and gives a flat representation of Qian Luozhi's (the astronomer royal's) tricolored chart, working from his celestial globe. It presents the celestial globe as projected onto a surface by the cylindrical projection technique, displaying over 1,350 stars in thirteen sections. One section is a planisphere — that is, in a kind of Mercator projection it depicts the circle of the sphere on a flat map centered on the north pole. The remaining twelve are flat maps centered on the celestial equator.

A century later, in 1094, Su Sung published further Mercator-style map projections in his book New Design for a Mechanized Armillary Sphere and Celestial Globe. One map had a straight line running across the middle as the equator and an arc above it, the ecliptic. The rectangular boxes of the lunar mansions are clearly seen, with the stars near the equator being more tightly packed together and those near the poles spread farther apart.

The evolution of Chinese instrumentation parallels that of the West. Notched jade disks and cylindrical sighting tubes date back to the fifth century B.C., and probably functioned as means of computing rudimentary celestial cycles. The Chinese used the gnomon as far back as 1500 B.C. Just as the Chinese had begun to standardize weights, measures, and other practical details in the sixth century B.C., and more extensively in the next three centuries, they standardized the gnomon. In addition to timekeeping, they used the gnomon to determine the terrestrial distance corresponding to an arc of the meridian. Such a determination of this north-south line was vital for precise calendar making, because precision calendars required measuring the latitude of those stations where the relevant observations were made. The gnomon was also significant in mapmaking and in the Chinese fascination with determining the size of the earth — nearly a millennium before Eratosthenes!

Between A.D. 721 and 725, under the auspices of the Buddhist astronomer and mathematician Yi Xing and the Chinese astronomer royal Nangong Yue, Chinese scholars set out to do this. To measure the size of the earth, they selected nine locations covering the prodigious distance of more than 3,500 kilometers (2,175 miles) on a nearly north-south axis. They made simultaneous measurements of shadows at the summer and winter solstices at all nine stations. The main outcome of this feat: they determined that the distance on earth corresponding to 1 degree latitude was 155 kilometers (97 miles). This is larger than today's value of 111 kilometers (69 miles), but far more accurate than previous attempts. Indeed, they found that the variation on shadow length with changed latitude was four times the value previously thought. There was no piece of research like it carried out anywhere else during the Middle Ages. In making his tabulations, Yi Xing used "tangent tables." This was thought to have been a Muslim invention of the ninth century, but it turns out that the Chinese discovered the use of tangents and tabulated them at least one hundred years earlier.

The Muslim big-observatory concept came to China in the thirteenth century, and during the Mongol dynasty, in 1276, the astronomer Guo Shoujing built a giant gnomon called Tower of the Winds. It was an all-purpose observatory with the tower itself serving as a gnomon. A horizontal rod in an aperture at roof level — about forty feet above the ground — cast a shadow on the long low wall extending northward below. A chamber at the top was designed for watching stars, while the inner rooms of the tower housed a water-driven clock and an armillary sphere.

Modern astronomical observatories derive not from the European tradition but from the Chinese. Modern telescopes are oriented and mounted in the equatorial system, which in China goes back at least to 2400 B.C. Equatorial mounting takes the equator as the horizontal circle around the side of the instrument, and the pole as the top point. Europeans originally followed the Greek-Indian-Muslim tradition in which the two circles that were important were the horizontal and the ecliptic, the circle described by the sun's motion in the sky that is in the same plane as the earth's orbit around the sun. This tradition more or less ignored the equator. China, meanwhile, largely ignored the horizon and the ecliptic. In the seventeenth century, European astronomers came to realize that the Chinese equatorial system was more convenient and showed greater promise. It was adopted by Tycho Brahe and his successors and remains the basis of astronomy today.

The Chinese, furthermore, had the skills to build the precision observational instruments to display this system. Having invented cast iron, they built large astronomical instruments of bronze and iron that took the form of armillary spheres — huge metal rings precisely graduated with the degrees of a circle.

Different rings representing different sky circles were joined together at the two points where they crossed each other. Always with an emphasis on the meridians, one ring would represent the equator, another the sky-circle meridian passing directly overhead and through the celestial pole. These devices had sighting tubes through which astronomers could observe specific stars. The astronomer could move the sighting tube along the equator ring until he found a star. Then he counted the number of degrees marked on that ring back to the meridian ring, which stood up from it at 90 degrees. As soon as he counted the degrees, he could detect the exact position of the star along the equator and tell which sky segment it was in. These instruments aided astronomers in drawing star maps with great precision.

The earliest known instrument of this type was built in 104 B.C., and the instrumentation became increasingly complex until the thirteenth century. Ken Shou-Ch'ang introduced the first permanently mounted equatorial armillary ring in 52 B.C. and in A.D. 84 Fu An and Chia Kmuei added a second ring to show the ecliptic. Chang Heng, the mapmaker, added a ring for the meridian in A.D. 125, as well as one for the horizon. But Chang Heng was not yet satisfied. He made an armillary sphere that rotated by water pressure in about A.D. 132. He used a wheel powered by a constant pressure head of water in a water clock to rotate the instrument slowly. This instrument was a tremendous tool for demonstrating and computing the movements of heavenly bodies.

An advanced version of the armillary sphere is the torquetum, first invented by Arabs sometime between A.D. 1000 and 1200. (Some credit al-Tusi for the invention.) Here all the various rings are no longer nested together in a single sphere but are mounted at various different parts of a set of struts in a way more efficient than that allowed by the constraints of a single sphere. In 1270 Kuo Shou-Ching made a metal torquetum called the "simplified instrument." It was purely equatorial, with all the Arab ecliptic components left out. It survives today at the Purple Mountain Observatory in Nanking. It was moved there from its home site at Linfen in Shanxi during the Ming dynasty when government officials no longer understood that the difference of 33—4 degrees in latitude caused by the move would render it useless. Needham called this "simplified instrument" the precursor of all equatorial-mounted telescopes. Needham believed that some knowledge of it eventually reached Tycho Brahe in Denmark three centuries later and led to Brahe's taking up equatorial astronomy for his instruments. Actually, an equatorial mounting of the kind devised by Guo Shoujing wasn't constructed in the West until 1791, when it was used for a telescope made in England, and thus its design became known as the "English mounting."

Astronomy was the first real science practiced by the world's ancient cultures. It was primarily observational (rather than experimental), but it meets most criteria for what a science should be. Next we will continue on to an associated discipline, cosmology. I write "discipline" rather than "science" because, as you shall see, it's not clear what cosmology is. Cosmology is dependent on astronomy, extrapolating its data to a worldview. Which is not to say that astronomers always agree with the tales spun by their cosmology colleagues.

Copyright © 2002 by Dick Teresi

from Chapter Seven

Chemistry: Alchemy and Beyond

Antoine-Laurent Lavoisier (1743-1794) was a financier, established a system of weights and measures that led to the metric system, lived through the early turmoil of the French Revolution, and was a pioneer in scientific agriculture. He married a fourteen-year-old girl and was beheaded during the Reign of Terror. He has been called the father of modern chemistry, and, in the course of his busy life, he brought Europe out of the dark ages of that science.

One of Lavoisier's early contributions resulted from his boiling water for long periods of time. In eighteenth-century Europe, many scientists believed in transmutation. They thought, for instance, that water could be transmuted into earth, among other things. Chief among the evidence for this was water boiling in a pot. Solid residue forms on the inside surface. Scientists proclaimed this to be water turning into a new element. Robert Boyle, the great seventeenth-century British chemist and physicist who flourished a hundred years before Lavoisier, believed in transmutation. Having watched plants grow by soaking up water, he concluded, as many had before him, that water can be transformed into leaves, flowers, and berries. In the words of chemist Harold Goldwhite, of California State University, Los Angeles, "Boyle was an active alchemist."

Lavoisier noticed that weight was the key, and that measurement was critical. He poured distilled water into a special "tea kettle" called a pelican, an enclosed pot with a spherical cap, which caught the water vapor and returned it to the base of the pot via two handlelike tubes. He boiled the water for 101 days and found substantial residue. He weighed the water, the residue, and the pelican. The water weighed exactly the same. The pelican weighed slightly less, an amount equal to the weight of the residue. Thus, the residue was not a transmutation, but part of the pot — dissolved glass, silica, and other matter.

As scientists continued to believe that water was a basic element, Lavoisier performed another crucial experiment. He invented a device with two nozzles and squirted different gases from one into the other, to see what they made. One day, he mixed oxygen with hydrogen, expecting to get acid. He got water. He percolated the water through a gun barrel filled with hot iron rings, splitting the water back into hydrogen and oxygen and confirming that water was not an element.

Lavoisier measured everything, and on each occasion that he performed this experiment, he got the same numbers. Water always yielded oxygen and hydrogen in a weight proportion of 8 to 1. What Lavoisier saw was that nature paid strict attention to weight and proportion. Ounces or pounds of matter did not disappear or appear at random, and the same ratios of gases always yielded the same compounds. Nature was predictable...and therefore malleable.

Ancient Chinese alchemy, circa 300 to 200 B.C., was built around the concept of two opposing principles. These could be, for example, active and passive, male and female, or sun and moon. The alchemists saw nature as having a circular balance. Substances could be transformed from one principle to another, and then rendered back to their original state.

A prime example is cinnabar, known commonly today as mercuric sulfide, a heavy red mineral that is the principal ore of mercury. Using fire, these early alchemists decomposed cinnabar into mercury and sulfur dioxide. Then they found that mercury would combine with sulfur to form a black substance called metacinnabar, "which then can be sublimed into its original state, the bright red cinnabar, when once more heated," according to science historian Wang Kuike. Both mercury's liquid quality and the cyclic transformation from cinnabar to mercury and back again gave it magical qualities. Kuike calls mercury "huandan, a cyclically transformed regenerative elixir" associated with longevity. These ancient practitioners became familiar with the concept that substances could be transformed and then come full circle to their original state. They developed exact proportions of the amounts of mercury and sulfur, as well as recipes for the exact length and intensity of the heating required. Most important, according to Kuike, these operations could be performed "without the slightest loss of the total weight."

It would appear that the ancient Chinese alchemists were empirically familiar with the conservation of mass fifteen hundred years before Lavoisier's experiment. He and his alchemist precursors discovered that the weight of the products in a chemical reaction equal the weight of the reactants.

The earliest alchemic text is Wei Po-Yang's Ts'an T'ung Ch'i (Unification of the Three Principles), written around A.D. 140. The work describes an experiment, very likely the cinnabar-mercury-sulfur reaction described above. It is difficult to be certain, because the chemicals going into the fire are called by metaphorical names: White Tiger (probably mercury), Blue Dragon, and Gray Dragon (sulfur?). More important is the vessel they used:

On the sides [of the apparatus] there is the walled enclosure, shaped like a peng-hu pot. Closed on all sides, its interior is made up of intercommunicating labyrinths. The protection is so complete as to turn back all that is devilish or undesirable....Like the moon lying on its back is the shape of the furnace and the pot. In it is heated the White Tiger. Mercury Sun is the flowing pearl, and with it the Blue Dragon. The east and west merge together, and the hun and po [two kinds of souls] control one another....The Red Bird is the spirit of fire and dispenses a victory or defeat with justice. With the ascending of water comes the vanquishing of fire.

The vessel is used for melting and subliming different metals. The instrument is similar to and more complex than Lavoisier's pelican, designed to "turn back" all products to ensure the conservation of mass.

The history of chemistry, Western and non-Western, runs counter to the history of physics. The latter contains a cornucopia of theory, with experiment lagging far behind. In chemistry we see a fascination with empirical knowledge, experimentation with all variety of substances (liquids, solids, gases), using all sorts of methods (fire, boiling, distillation), but without a solid theoretical framework to guide the experimentation. The movie image of the frizzy-haired scientist in his lab sloshing together beakers full of brightly colored chemicals is not too far off. Chemistry has been a science of trial and error. The theory has not always been of the highest quality.

The West developed a coherent theory that predicted which elements will combine with each other and which will not, why some compounds are possible and others aren't, and what precisely will happen when one chemical is combined with another. In addition to Lavoisier there were two great pioneers in this area.

In 1869, at the University of St. Petersburg, the Siberian-born Dmitry Mendeleyev could find no good chemistry textbook to assign to his classes. He began writing his own. Like Lavoisier and the ancient Chinese, he saw chemistry as "the science of mass." He enjoyed playing patience, a variety of solitaire, so he wrote the symbols of the elements with their atomic weights on note cards, one element per card, with its various properties listed (e.g., sodium: active metal; chlorine: reactive gas).

Mendeleyev arranged the cards in order of increasing atomic weight. He noted an obvious periodicity (hence, the "periodic table of the elements," as his arrangement came to be called). Elements with similar chemical properties were spaced eight cards apart. Lithium, sodium, and potassium, for example, are all active metals (they combine vigorously with other elements, such as oxygen and chlorine) and their positions are 3, 11, and 19. Hydrogen, fluorine, and chlorine are active gases, and hold positions 1, 9, and 17. Mendeleyev rearranged the cards in a grid of eight vertical columns. Reading across, the elements get heavier. Reading down, the elements in each column display similar properties.

Mendeleyev did not feel compelled to fill in all the slots in the grid, knowing that, as in solitaire, some of the cards remain hidden in the deck. If a slot in the table called for an element with particular properties and no such element existed, he left it blank. Mendeleyev was widely ridiculed for these gaps in the periodic table. Five years later, though, in 1875, gallium was discovered, and fit in the space beneath aluminum, with all the properties predicted by the table. In 1886 germanium was discovered, and fit in the space beneath silicon. No one has laughed since. Mendeleyev never won the Nobel Prize in chemistry, though he was alive and elgible during its early years. However, three chemists who found "gap" elements did win: William Ramsay, who discovered argon, krypton, neon and xenon; Henri Moissan for fluorine; Marie Curie for radium and polonium.

Growing up in the 1950s and '60s, I, like other students of that era, spent many hours staring at Mendeleyev's periodic table, hung on classroom walls across the country. The periodic table is less in evidence today, which is unfortunate since it inculcates in even the slowest mind the importance of atomic number, an element's placement in the periodic table. The striking qualitative differences among the elements — carbon seems little like hydrogen, or lead like helium — are, on a basic level, differences in atomic number, which we now equate with charge on the nucleus.

The meaning of the periodic table and its regularities and repeating patterns remained hidden until the early twentieth century, when the atom was dissected, and physicists found electrons inside and a nucleus comprising protons and neutrons. Elements differed from one another because of the number of protons and neutrons in the nucleus and the number of electrons whizzing around them. Quantum theory ensued.

One of the pioneers of the quantum heyday (1900 to 1930) was Wolfgang Pauli. He didn't intend to solve the mystery of the periodic table; he was simply trying to understand the atom. Pauli was famous for his acerbic sense of humor. He spared no one. When the celebrated physicist Victor Weisskopf, at the time Pauli's assistant, presented him with a theoretical effort, Pauli said, "Ach, that isn't even wrong!" Pauli also sent a letter to Albert Einstein, recommending a student as an assistant. "Dear Einstein," Pauli wrote, "This student is good, but he does not clearly grasp the difference between mathematics and physics. On the other hand, you, dear Master, have long lost this distinction."

In 1924, Pauli announced the exclusion principle: no two electrons can occupy the same quantum state. It explained the order in Mendeleyev's table, and why we can use it to predict which elements combine with which and how. I won't go into the specifics of what constitutes a quantum state here. Suffice it to say that Pauli's exclusion principle limits the numbers of electrons in what we now call the "shells" of each atom: two in the first, eight in the second, eighteen in the third, and so on. Hydrogen, for example, has but one proton in its nucleus. To balance its single positive charge, we need one electron (negative charge), which occupies the lowest energy state, or orbit. Next in the table is helium. Its nucleus has two plus charges, so we need two electrons, which, according to Pauli's principle, fit together in the first shell.

When we get to lithium, and its three positive charges in the nucleus, we need three electrons. Two go in the first shell, but the third must be put in the second shell. This shell has a much larger radius than the first, and with only one of eight electron slots filled, we can see why lithium is an active metal, combining with other atoms with ease. When the outermost shells are filled, it is impossible to add an electron. The electromagnetic resistance is huge. When there are slots open, it's time to do business.

The Hindenburg blimp is a prime example of this principle. Its tragic explosion over Lakehurst, New Jersey, in 1937 illustrates the Pauli principle. The United States had refused to export helium to Germany, so German dirigibles were inflated with hydrogen. Helium is safer because its two electrons fill its shell, making it an inert gas. Hydrogen has only one electron, making it an active gas, a fact that was evident when the Hindenburg went up in flames.

Hydrogen and helium are dissimilar despite differing by only 1 in atomic number. The vertical columns in the periodic table, on the other hand, contain elements whose outermost shells hold the same number of electrons, and thus these elements have similar chemical properties.

Thanks to Lavoisier, Mendeleyev, Pauli, and many others, seventh graders can do and understand experiments that would have seemed like magic to chemists working only a few centuries ago. Only in the past three-quarters of a century, thanks to Pauli, have we understood why chemicals mix and react as they do. It becomes clear to us why sodium and chlorine can combine to form salt, or hydrogen and oxygen to make water. I'm speaking theoretically. Not everyone grasps this valuable knowledge.

Alchemy is normally associated with the pseudosciences and primitive, superstitious cultures. In a narrow sense, alchemy is the attempt to turn lead or other base metals into gold. Another goal of alchemists was to find an elixir of eternal youth. As we shall see here, alchemy can also be defined as an early form of chemistry.

The ambition to turn lead into gold is not so crazy. As we've seen, atomic number is the key to chemistry, and lead's number is similar to gold's, the elements being close to each other on the periodic table (atomic numbers 82 and 79, respectively), though, of course, the ancients didn't have a periodic table.

One of the first Nobel Prizes in chemistry was awarded in 1908 to Ernest Rutherford, who discovered that through radioactivity some elements transform into others. The elements are alterable. Listen to Rutherford's famous exchange with his collaborator Frederick Soddy.

Soddy: "Rutherford, this is transmutation."

Rutherford: "For Mike's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists."

Rutherford went on to transmute elements in another way, bombarding them with particles to break off protons, "smashing the atoms" to turn them into lighter elements.

In 1938, the Italian physicist Enrico Fermi won the Nobel Prize, in part for supposedly discovering new radioactive elements heavier than uranium. Fermi had bombarded uranium, atomic number 92 on the periodic table, with slow neutrons, and had produced two mysterious substances, which in his Nobel acceptance lecture he called "ausonium" and "hesperium," elements 93 and 94. Actually, Fermi had split the uranium atom into lighter elements, not added neutrons to make heavier elements. He had unknowingly produced fission. In 1939, Otto Hahn and Fritz Strassman, with some interpretative help from Lise Meitner and Otto Frisch, split the uranium atom, and realized they had achieved fission. (Fermi's prize was well deserved; he was a great physicist, a "god" in the parlance, and had many other Nobel-level achievements.) In 1940, Edwin McMillan and Glenn Seaborg accomplished what Fermi's work had hinted at. They created the transuranic elements neptunium and plutonium via bombardment. They won the Nobel Prize in chemistry in 1951.

We will meet ancient and medieval chemists who believed in alchemy and transmutation. Their ideas have been championed, if reluctantly, in our era by such men as Rutherford, Fermi, McMillan, and Seaborg.

Prehistoric peoples' first dabbling in chemistry involved any process that transformed initial ingredients: cooking, dressing hides, working metals, making medicines, painting and dyeing, and making pottery. Eduard Farber, a historian of chemistry, defines it as "the selection, separation, and substantial modification of materials. In the ancient world, fire, the most visible agent of transformation, was at the heart of chemistry. Water also holds an important role in early chemistry as the principal dissolving medium. An exact understanding of what early peoples knew about chemistry is hampered by the numerous names used for the same substance, by a single name denoting vastly different substances, and by the unknown amount of impurities involved in any process, even when the terms are clear.

Alchemy may have been denied its proper place in the history of chemistry because of an inability to interpret the religious, philosophic, and symbolic traditions that embodied its knowledge. Alchemists' fondness for metaphor, such as two lions being emblematic for sulfur, made it unintelligible to literal-minded people. In the chemist John Read's words, "It is easy to despise something which one makes no effort to understand." Ages hence, one wonders what scholars will make of some of our "modern" terms in physics and astrophysics: Winos, WIMPS, quarks, dark matter, the eightfold way, superstrings, big bang, and the like.

Alchemists pioneered one technique that laid the foundations for much of modern chemistry: they experimented. The mystical-religious thinking surrounding alchemy also played a significant role, giving rise to beliefs that were later to become precepts of modern chemistry: conservation of matter, phase changes, and energy transfer. Alchemic mysticism connected the transformation of solid substances into liquids and vapors with the transformation of the human body into the soul. Sublimation, in which a solid converts directly into a vapor, in particular seemed analogous to the spirit leaving the body, and the magical recrystallizations out of a melt or vapor were connected with ideas of reincarnation and rebirth.

Alchemy was philosophy. Alternatively called hermeticism, alchemy had as its primary intention the regeneration of the human soul from its present sensory-dominated state into its original divine condition. It was about raising the life essence of things — metals in particular — to a nobler form.

It's unclear where alchemy originated; some scholars say it began in Egypt and was filtered to China; others say it began in China. Alchemic ideas are seen in Hindu writings from 1000 B.C. in the Arthava Veda. In any case, alchemic ideas were seen far earlier in India, Egypt, and China than in Greece. Let us start with Egypt.

Egypt

The Greeks thought of Egypt as the source of earliest alchemy, and they admired the ancient Egyptian skill in "enameling, glass-tinting, the extraction of plant oils, and dyeing — all dependent on chemical knowledge," according to John Read. "For such reasons, Egypt, or Khem, the country of dark soil...has often been pictured as the motherland of chemistry," he writes. The word chemeia, Greek for a "preparation of silver and gold," may have roots in Khem. Other sources claim that chemyia has origins in word meaning to pour, while scholar Bruce Bynum says that Kem, and al-kemit (as in "alchemy") referred not to Egypt's soil but to the earliest people of the upper Nile who established the Nubian, or Kemetic, civilization. They were black Africans. Hence, to the Greeks Kem came to mean "land of the blacks." Other researchers believe that the Egyptian ideas came from Persian, Chaldean, and Hebrew sources.

Third-century A.D. papyri from Thebes, copied from even earlier texts, may be the earliest records of alchemic schemes for turning base metals into silver and gold. The papyri contained little theory but much practical information on the alloys going into different metals. Alchemy was, however, related to Egyptian philosophical and religious views, and, in a sense, to mummification, according to Eduard Farber:

Egypt, the land of the black earth, was devoted to the cult of the dead. The god Osiris is revived from death after he has been ritually wrapped in bandages. To the Egyptian's mind, this indicated a valid analogy to the fact that minerals are bandaged and entombed in black lye to revive them into metals.

Priests presided over this "embalming" of metals, which came from the dark earth to be transformed (they hoped) into gold. The Egyptian practice of embalming the dead was a logical extension of this belief and, according to Farber, an indication of how matter acted powerfully on the human spirit and life. Life, spirit, and physical elements were interconnected in ancient Egyptians' minds.

This concept of material transformation must have fascinated early Egyptians as they watched metals change color and form after heating or undergoing other processes. The later Alexandrian alchemists (fourth through seventh centuries A.D.) emphasized a color progression in making gold: black was the first stage, from fusing "base metals" such as lead, tin, copper, and iron, or lead and copper with sulfur; bleaching was next, accomplished by firing the black compound with arsenic, silver, mercury, antimony, or tin. Next the substance was yellowed using gold or a lime-sulfur mixture. Finally the color violet prevailed. Violet-colored gold seems odd (and less than authentic) to us, but to the Egyptians this was a kind of heightened gold, the essence of gold, something that was seen as so powerful that it acted like "a yeast" to transform the metal into a spiritual substance. The concept of yeast was seminal in ancient thinking, signifying something very tiny that causes huge changes. In a sense yeast is a precursor to chemical ideas of catalysts or enzymes and is related to the Chinese and later Arabic elixirs of life.

Keeping in mind the Egyptian connection of physical matter with spirit, the vapor of distillation during these processes was associated with spirit, while the remaining "base" material was the body, the corpse. This clearly relates to the chemical process of sublimation, in which solid matter directly turns to gas. The transformation of substances is an early way of thinking about the phase changes of matter from solid to liquid to gas.

Embalming was the first step to take the human spirit from its dead body to reincarnation. The Greek Herodotus (fifth century B.C.) describes the process:

First they draw out the brains through the nostrils with an iron hook, raking part of it out in this manner, the rest by the infusion of drugs. Then with a sharp stone they make an incision in the side, and take out all the bowels; and having cleansed the abdomen and rinsed it with palm wine, they next sprinkle it with pounded perfume. Then, having filled the belly with pure myrrh, cassia and other perfumes, they sew it up again;...they steep it in natron, leaving it under for seventy days....At the expiration of seventy days they wash the corpse, and wrap the whole body in bandages of waxen cloth, smearing it with gum, which the Egyptians commonly use instead of glue.

The natron in which the body is steeped occurs naturally in Egyptian lakes. Chemists debate what natron was; some label it a sodium carbonate and bicarbonate precipitant, others a sodium aluminum silicon oxygen salt. It is now believed that the steeping in natron killed bacteria and dehydrated cells, while wrapping the corpse and sealing it in a tomb kept it from moisture and air. "All in all," write Cathy Cobb and Harold Goldwhite in their book Creations of Fire: Chemistry's Lively History from Alchemy to the Atomic Age, "the process was not much more mysterious than salting pork." (The Hawaiians also preserved bodies by gutting and filling them with salt obtained from evaporated seawater. A body treated in this manner was termed ia loa, long fish.)

As much as gold was revered in ancient Egypt, the occupation of goldsmith was not appealing to everyone. An ancient instruction book tells how Dua-Khety, a man living in the Middle Kingdom in Sile, wished to place his son Pepy in writing school rather than have him seek a profession as a goldsmith. "I have seen a smith at work before his furnace door, his fingers like [the claws of] crocodiles. He stinks more than fish roe." The smell refers perhaps to the fumes resulting from the many chemical procedures done to gold, the curled fingers perhaps a symptom of heavy-metal poisoning. Still, this did not deter others from falling prey to the allure of gold.

The desired end product of alchemy, gold, is found pure in nature and dates from the Stone Age of Egypt. However, the earliest Egyptians could not separate gold from silver. Sometimes Egyptian gold was so rich in silver it seemed a different metal, variously dubbed white gold, asem, or electrum. The nineteenth-century French chemist Marcelin Berthelot analyzed artifacts from the Twelfth Dynasty (ca. 2000 B.C.) and found the metal to contain around 85 percent gold and 15 percent silver. Later (circa 1300 B.C.) methods of separation involved heating the gold-silver alloy repeatedly with common salt, which eventually transformed the silver into silver chloride that would pour off into the slag.

The two papyri of alchemic recipes found at Thebes were first translated into Greek and then into Latin, the version Berthelot analyzed. The papyri are a collection of chemical recipes for making metallic alloys; producing imitations of gold, silver, or electrum; dyeing; and other related arts. The formulas are unabashed about their intended deception, so as to whether Egyptians saw no contradiction between "real" and "fake" gold, or whether the writer(s) were of a more practical nature than the priests, we can only speculate. Berthelot explains:

The parts dealing with the metals are largely concerned with producing passable imitations of gold, silver or electrum from cheaper materials, or with giving an external or superficial color of gold or silver to cheaper metal....There are often claims that the product will answer the usual tests for genuine products, or that they will deceive even the artisans.

Here is a recipe for fake silver (amalgamated tin):

Tin, 12 drachmas [3.411 grams]; quicksilver, 4 drachmas; earth of Chios [white clay], 2 drachmas. To the melted tin add the powdered earth, then add the mercury, stir with an iron, and put it into use"

To make artificial pearls:

Mordant [fix] or roughen crystal in the urine of a young boy and powdered alum, then dip it in "quicksilver" and woman's milk.

"Crystal," in this case, probably refers to softer, absorbent, transparent stones rather than to quartz, which would not soak up the solution. "Quicksilver" is probably fake mercury, made perhaps of mica or fish scales. Today, of course, it is more problematic obtaining young boys' urine and woman's milk. Urine, an alkali, was mixed with alum (potassium aluminum sulfate) to fix colors. We're not sure of the purpose of woman's milk.

The making of skin creams and perfumed oils was highly developed in Egypt, as well as in Mesopotamia. Salves, ointments, oils, eye shadow, and nail paint protected the skin from the desert environment and had religious significance. In 2450 B.C., the sage Ptah-Hotep wrote, "If thou art a man of standing, thou shouldst found thy household and love thy wife at home as is fitting. Fill her belly; clothe her back. Ointment is the prescription of her body."

Animal fat or vegetable oils from castor, colocynth, lettuce, linseed, olive, and safflower served as the base to which aromatic oils were added. Oil from anise, cedar, cinnamon, citron, mimosa, peppermint, rose, and rosemary were popular. The method of extracting the oils is uncertain but could have involved boiling mashed herbs in a pot covered with fat-impregnated cloth, the fat then soaking up the scent, a method still used by peoples along the Nile. Other methods include steeping flowers in fat until the odor was taken up by the fat, and dipping flowers in hot oils and straining off the liquid. Egyptians most likely expressed the oil by squeezing the ingredients in a cloth bag using wooden sticks. R. J. Forbes, a historian of technology, indicates that "milk, honey, salts and such aromatic gun-resins and oleo-resins" were included in beauty products, some of which probably fixed the volatile nature of the oils.

Cosmetic recipes were set down in a sixteenth-century B.C. text, the Edwin Smith Surgical Papyrus, which apparently was a copy of a much earlier document. Its begins by stating, "Beginning of the Book of Transforming an Old Man into a Youth," a sentiment close to modern people's use of cosmetics.

Recipe for transforming the skin: Honey 1, red natron 1, northern salt 1. Triturate [pulverize] together and anoint therewith.

Honey and milk were common bases for cosmetics in Egypt and Mesopotamia. Forbes compares this recipe to modern skin lotions that include "alcohol, glycerine, lactic acid (85 percent), water and perfume." The Egyptians also practiced dandruff control, using potions composed of ground and roasted barley, bran powder, and soft grease, topped off with applications of fish oil and hippopotamus fat. Given shortages of hippo fat, modern dandruff shampoos rely on soft greases such as beeswax, lanolin, petrolatum, olive oil, or liquid petrolatum to dissolve the dry cuticle. The Egyptians also used powdered antimony and green malachite for eye shadow.

Natron was used both as a bleach for linen and as a kind of soap mixed with clay. The importance of soap is demonstrated by the fact that natron and other soaps made from soda and castor oil were overseen by the Egyptian authorities, who taxed the launderers' use of these materials. Wool was cleaned with ashes (which would provide alkaline carbonates as reagents) and clay-water, which would work together as an abrasive substance.

The Egyptians concocted a wide range of dyes, including purple, red, rose, yellow, green, and blue, made from safflower, orseille, woad, mulberry juice, pomegranate blossoms, cinnabar, and iron oxide. The prize of the Egyptians was kermes, the dried pulverized bodies of female scale insects they used to make red and purple dyes. Of course, kermes's history predates its Egyptian use. Pre-eighteenth-century B.C. Persians dyed their rugs with kermes, which is the root of the words "crimson" and "carmine." Blue dye was also popular, but we won't go into the details of its fabrication here. Suffice it to say that, once again, it involves urine. Also pivotal to Egyptian dyeing was something called the Phrygian stone, which, according to Pliny (writing in the first century A.D.), was a pumicelike stone soaked in wine and then heated three times. When wool was boiled with the Phrygian stone, mixed with algae, and washed in seawater, it would turn purple.

Copyright © 2002 by Dick Teresi