Absolute Zero and the Conquest of Cold (8 page)

In 1724 Fahrenheit was elected as a foreign member of the Royal Society and went to London. Just before this trip, he did some significant though haphazard basic experiments to determine some fixed points for his thermometers. In a 1729 letter to Boerhaave, Fahrenheit first apologized for any delay in delivery of his thermometer, saying he was "now seeking a friend of the fair sex, which matter, as you will understand, will take up much of my time until it is resolved," then told of his pre-1724 research on the artificial production of cold.

These experiments were like a chance visit to an unknown territory by someone unprepared to be a proper explorer but who grasped the opportunity of an accidental landing to climb a mountain, view the lay of the land, and record a few observations of unusual phenomena. Mixing aquafortis (concentrated nitric acid) and ice, Fahrenheit reduced the temperature of his mix to a point so low that the largest measuring tube he had was not long enough to measure it. Intrigued, he constructed a thermometer able to register as far down as 76 below his 0 and managed to lower the temperature of an aquafortis/ice mixture to 29 below.

Next, using a series of beer glasses with freezing mixtures in them, he tried what would later become known as a cascade series: he cooled the first glass with his original aquafortis/ice mixture until the mix registered its lowest temperature; then he poured off the liquid in the mixture and used the solid that remained on the bottom as the starter for the second glass, to which he added more liquid, enabling him to reduce the temperature of the second glass to 32 below; continuing the technique, he reached down successively to 37 and then to 40 below. He boasted to Boerhaave that he could have gone still lower had he had purer chemicals. During this exploratory descent, Fahrenheit also managed to create crystals from some liquids. Not well enough schooled to make advanced scientific conclusions from his experiments, he "humbly" wrote to Boerhaave the prescient observation that "we know just as little of the first commencement of heat as we know of the extreme limit of heat."

After his sole excursion into the territory of the cold, Fahrenheit returned to what he did best, the manufacture of measuring implements, and confided in his next letter to Boerhaave that friends of the young lady he was courting, who wanted her money, had influenced her to spurn his advances. Free of the distraction of finding a wife, he immersed himself in the technical problems affecting his thermometers' precision of measurement and comparability with one another. He was vexed because the various kinds of glass used for tubing yielded differing results and because the inconstant purity of the mercury he bought made it nearly impossible to accurately fill two bulbs with precisely the same amount of liquid mercury—he would tolerate only an error margin of 5 parts in 11,520, or 0.05 percent.

Although his thermometers were bought and used throughout Europe, Fahrenheit died penniless in 1736; he had spent everything he earned from the ones he sold on research and on materials for newer ones. Good as Fahrenheit's thermometers were, they came into general use only in those countries where the language of choice was not French. No matter what the field of endeavor—astronomy, agronomy, or meteorology—the French liked to use their own measurements; there were, for instance, 18 kinds of the unit of length known in French as the
aune,
and in one district, 110 measures for grain. The French considered Fahrenheit to be Dutch/Polish and would not use his thermometers. Instead, they preferred thermometers with a scale created by René-Antoine Fer-chault de Réaumur. This highborn savant had done very credible work in botany, ferrous metallurgy, and embryology, and he considered his thermometric work less worthy of attention than his other scientific endeavors. He was right about that, for his thermometric scale was not even a true innovation, simply reproducing Hooke's scale without attribution. Yet Réaumur wrote so extensively about his thermometric scale that his scientific memoirs took on the force of public-relations efforts and pushed the French to adopt it, even though Réaumur thermometers froze at low temperatures and had to be modified to be useful. Réaumur also advanced his cause by actively dissuading experimenters from using Fahrenheit-scale thermometers, and when other thermometers marked with a "centigrade" scale began to show up on the Continent, he went out of his way to disparage and suppress them, too.

In this latter effort he failed, because in time the centigrade scale, the most logical and most useful measuring innovation developed during the first 150 years of the thermometer, would supplant Réaumur's and almost all other scales. In terms of accuracy, fixed points, and utility of the scale to the needs of researchers, centigrade-scale thermometers reached as far as was then technologically feasible. They became extremely important tools for exploration of low temperatures.

In 1948 the Ninth International Conference on Weights and Measures decided that the points on the centigrade scale that had been known as "degrees centigrade" should henceforth be known as "degrees Celsius," to honor Anders Celsius, who had invented the scale. Success has many fathers, and despite the twentieth-century canonization of Celsius as the inventor of centigrade, there remains a whiff of controversy as to the true claimant to that title.

In 1740, the year before Celsius was supposed to have invented the scale, Reaumur was grumbling to his diary about centigrade scales, and there is also evidence that several Swedes other than Celsius could lay claim to having formulated the centigrade scale. The instrument maker Daniel Ekström had worked in England with the thermometer maker for the Royal Society, and an Ekström-modified London thermometer appears to have been in use at Uppsala University since 1726—a thermometer on which the freezing point of water was at o° and the boiling point at 100°. Two other potential claimants for the title of father of centigrade were Märten Strömer and the botanist known to history as Linnaeus.

Anders Celsius's centigrade scale had the distinction of being born as a direct result of a visit to the geographic country of the cold. Celsius was the son and grandson of astronomers, and his main work was in that discipline; he mapped the aurora borealis, studied the light of the moon, changed the Swedish calendar from the Roman Julian to that used by other countries in the eighteenth century, and was a participant in an international scientific expedition that journeyed far inside the Arctic Circle to help verify Newton's theory that the earth was flattened at the poles. On that trip in the 1730s, Celsius became dissatisfied with the instruments then available for measuring the considerable cold in the air and on the ground.

He was an unusual man, recalled by memoirs as being quite learned, able to converse in a half-dozen languages and interested in ancient runes, a man of "harmonious" personality and grand vision but also a man of honor, one who defended ideas he thought were correct, his own as well as those of Newton—this last contention reflecting a controversy in which Celsius's astronomical observations that verified Newton's were viciously attacked by a leading Continental scientist, then eventually proved correct.

In 1741 Celsius obtained a thermometer from St. Petersburg and etched on the side opposite its scale a formulation of his own. It had two fixed references, the boiling and freezing points of water, which he designated, respectively, as o° and 100°; like his fellow astronomer Rømer, Celsius was more concerned with the accuracy of the near-freezing temperatures than with the near-boiling ones. His thermometer was first used on Christmas day 1741, and he wrote about that use in a 1742 publication, stressing the handiness for calculations of having 100 demarcations between his two fixed points. Two years after this publication, Celsius died, at the age of forty-two.

Strømer made a centigrade thermometer in 1750, on which he simply reversed Celsius's scale, putting 100 at the top and 0 at the bottom; as Celsius's successor at Uppsala, Professor Strømer would not think of claiming credit for his predecessor's innovation. But Carolus Linnaeus could and did try to do so. In 1758 Linnaeus claimed to have been the originator of the centigrade scale.

That Linnaeus would even want to make such a claim underlines the importance to science the centigrade scale had achieved in a relatively short period of being in use. In 1758 Linnaeus was the most celebrated botanist in the world, a man whose fame as a scientist outshone that of virtually all others of his time. He was also one of the most egocentric scientists who ever lived, a man who told others that God had anointed him to promulgate the rules of classification and who believed that all his publications were masterpieces. Linnaeus brooked no criticism of himself, even as he vacillated between extremes of exhilaration and despair over his work and worth. Knowles Middleton suggests that in Linnaeus's mind, his claim on centigrade probably dated back to 1735, when he had lived for a time on the estate of a wealthy Dutch planter and had written a book about the gardens there; one illustration shows angelic putti holding what appears to be a thermometer with a scale that goes from 100 at the top, down by tens to 1 in the middle—not to 0—and then down again by tens to 100 at the bottom. However, Middleton points out, the text of Linnaeus's book does not refer to the instrument in the illustration at all but does mention a hothouse containing African violets kept at a temperature of 70. Since on a centigrade scale a 70° temperature would scorch such plants—40° would be about their limit—it is likely that Linnaeus's text reference was to a thermometer etched with a non-centigrade measuring scale. So Linnaeus can be credited, at most, only with inverting Celsius's scale.

As for the date of his claim to inventing the centigrade scale, the botanist apparently chose not to initially lay claim to inventing the centigrade scale before 1758, because earlier he was indebted to Celsius, who was pushing hard to obtain something for Linnaeus that he desperately wanted at that time—a position at Uppsala University. In deference to his sponsor, Linnaeus delayed making a claim of invention of the centigrade thermometer scale until more than a decade after Celsius was dead.

D
URING THE EXCEPTIONALLY FRIGID WINTER
of 1740, workers in St. Petersburg harvested from the Neva River square blocks of pure ice and with cranes and pulleys hauled them to the bank. Some blocks were so large that each took up an entire horse-drawn wagon, so it appeared to onlookers as though the wagon was burdened with one huge diamond or sapphire. The workmen were said to resemble mythical or allegorical figures, their beards and hair caked with congealing ice, their visages contorted by grimaces as they toiled in the bone-chilling cold. Using water to fasten one block to another, the workers erected, for the empress Anna, a translucent palace 56 feet long, 21 feet high, and 18 feet in depth. They painted the window frames to look like green marble, and at night they placed inside lit candles, which shone out from the windows. The ice palace produced "an effect infinitely more beautiful than if it had been built of the most costly marble, its transparency and bluish tint giving it the appearance of a precious stone," one observer wrote.

Shortly, the palace became more than a jewel to gaze at; it was used as the setting for an unusual series of tableaux. A young man and a young maid were dressed in old and colorful Russian peasant costumes taken from a collection of ethnographic displays already accumulated by past tsars, and an ice marriage was mounted to amuse the court. The bridal couple was drenched in water, which formed a light ice coating around them for the duration of the tableaux. After the ice palace had been on display for a while, workmen cut the blocks apart and stored them in the ice cellars of the Imperial Palace, for use in summer months to cool drinks and to refrigerate produce.

In hereditary monarchies such as those of Russia and France, where nearly every sort of commerce capable of yielding large quantities of money was controlled by the crown, the ice trade was a royal prerogative, with monopolies on the gathering and sale of ice granted to court favorites. To properly maintain a courtier at Versailles in the time of Louis XIV required 5 pounds of ice a day. Even in countries where the ice trade was not royally controlled, it was a pleasure reserved for the rich. Only such wealthy Virginia planters as George Washington, Thomas Jefferson, and James Madison could afford icehouses on their farms. In Philadelphia, convicts harvested ice from the frozen Schuylkill River for sale to the public, but few citizens could afford to pay 6 cents a pound. Furthermore, religion-based reluctance to modify temperatures with ice continued; as a contemporary account reports, "Some thought a judgment would befall one who would thus attempt to thwart the designs of Providence by raising flowers under glass in winter, and keeping ice underground to cool the heat of summer."

The reserving of ice for the titled and the rich, the high price of ice, and the religious reluctance to use it found echoes in the scientific laboratories' deliberate distaste for the practical consequences of refrigeration experiments. In 1748 professor of medicine William Cullen did something remarkable in the first chemistry laboratory in Scotland, at the University of Glasgow: he created artificial refrigeration. Basing his work on the recognized phenomenon of cold being produced by evaporating liquids, he tried to intensify the effect by means of a vacuum. Working with "nitrous aether," he exhausted a vessel of its air, which froze the water in another vessel that surrounded the apparatus. Content to write up
Cold Produced by Evaporating Fluids
for publication in a Scottish journal, Cullen did not attempt to exploit the effect commercially.

Neither did English physicist Edward Nairne, who in 1777 improved on Cullen's work by adding another step to the process. As Cullen did, Nairne used a vacuum to evaporate water through a reduction of pressure, but he then employed sulfuric acid to absorb the evaporated water. The absorption process accelerated the rapid drop in temperature of the water in the surrounding vessel and turned that water into ice more quickly than Cullen's simpler process had done. Still, sulfuric acid was so dangerous to work with, and Nairne's process produced so little ice, that while the experiment was frequently replicated in teaching laboratories over the next fifty years, it was not thought of as having commercial applications. It remained little more than a way to demonstrate the "affinity" between sulfuric acid and water. The production of ice was a theatrical grace note that helped students remember and appreciate the general principle.