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Radar, Hula Hoops, and Playful Pigs
67 Digestible Commentaries on the Fascinating Chemistry of Everyday Life
By Joseph A. Schwarcz
ECW PRESSCopyright © 1999 ECW Press
All rights reserved.
THOSE FASCINATING CHEMICALS!
The Lot of Lot's Wife
The tourist guide points to a pillar of stone as the bus leaves the Dead Sea and enters the Negev desert. "That is Lot's wife," he explains in a serious tone. Ears perk up as he quickly relates the familiar Bible story of the righteous Lot and Mrs. Lot, who were warned by the Almighty about the impending destruction of Sodom and Gomorrah. "They would be allowed to leave without fear of being harmed as long as they didn't look back upon the firestorm which would consume the evil cities. But Mrs. Lot's curiosity got the better of her — she sneaked a peek and immediately turned into a pillar of salt. And there she has stood for millennia."
There are chuckles all around, and some of the less sensitive husbands even poke their wives as if to underline the hazards of being too curious. Finally, though, the pillar story is passed off as a bit of tourist-guide fluff. But is that all it is? A chemistry professor at Northwestern University in Chicago has argued otherwise.
In a paper submitted to the prestigious Journal of the Royal Society of Medicine, Dr. I.M. Klotz has claimed that there is a scientific explanation for the tale of Lot's wife. In an article filled with equations, formulas, and high-powered technical language, Klotz explains how Mrs. Lot could have literally turned into a pillar of calcite, a form of the common mineral calcium carbonate.
Everyone knows that our bones contain calcium, but fewer are aware that our blood and tissues also contain the mineral. Indeed, our nervous system and heart could not function in the absence of calcium. It is also a well-established phenomenon that when organic matter burns carbon dioxide is produced. Without a doubt, massive amounts of carbon dioxide were released in the inferno of Sodom and Gomorrah.
When Mrs. Lot turned around she got a good whiff of that gas, and this triggered an instant reaction in her tissues, with the calcium forming insoluble calcium carbonate. According to Professor Klotz, she literally turned to stone, dying of "rigor calcium carbonatus."
An interesting thesis. The journal's editors obviously thought so, deeming it worthy of publication. There is only one problem with this fascinating chemical saga: it is utter nonsense. A moment's reflection immediately reveals that the few grams of calcium present in human tissues could never turn a body to stone, even if the reaction with carbon dioxide were a possibility. Could a chemistry professor make such an elementary error? Of course not. Dr. Klotz was not making a mistake — he was making a point.
He wanted to show how easy it is to get nonsense published in the scientific press. The people who review articles submitted to the Journal of the Royal Society of Medicine tend to be medical doctors. In all likelihood, they had long forgotten their basic chemistry and assumed that Dr. Klotz's complicated chemical discussion made sense. Klotz undoubtedly enjoyed reading the letters to the editor that focused on the nuances of his theory.
What are we to learn from this bit of mischief? That a degree of skepticism is very healthy when dealing with information. Nonsensical arguments can sound very logical and be very persuasive in the absence of pertinent background knowledge. Perhaps the next time we read about alien abductions, psychic spoon-bending, or the latest dietary supplement that cures all of humanity's ailments, we will benefit from reflecting on the mischievous chemical lot of Lot's wife.
Basking in the Limelight
Everyone likes to be in the limelight now and then, but who gets the chance anymore? Tungsten light, maybe. Or halogen light. But lime light — no.
Have you ever wondered where the term "limelight" comes from? It has nothing to do with the common green fruit that, coincidentally, happens to be called a lime. It has everything to do with the chemical calcium oxide, which is also known as lime. This white compound, which can be granular or lumpy, has an amazing property. It becomes incandescent when heated.
Before electricity, theatrical stages were bathed in the light generated by heating calcium oxide. A lens fitted in front of the glowing lime focused the light and enabled actors to bask in the glory of the limelight. The light was spectacular, and so was its chemistry. It was also a little scary.
The problem, in the theater, was to find a way to heat the lime to the necessary temperature, and the solution required some very clever chemistry. Starting in the early 1800s, the flame that heated the calcium oxide was produced by burning hydrogen in the presence of oxygen, but this was long before these gases could be purchased in cylinders. They had to be generated on-site.
In those days, the under-stage area was a veritable chemical laboratory. Here hydrogen was made by dropping pieces of zinc into sulfuric acid. The gas was then collected and stored in large, bellows-shaped bags. Oxygen was generated by heating potassium chlorate with manganese dioxide. It, too, was stored in gasbags. The hydrogen and oxygen bags were connected to the limelight by pipes, and when illumination was needed the emerging hydrogen was ignited. Obviously, theater fires were a constant threat.
Today, of course, we don't have to rely on lime for spotlights, but lime itself is still in the spotlight. In fact, it would be hard to picture modern life without it. Lime is made by heating limestone (calcium carbonate) and is widely used in agriculture. It is an alkaline substance, or "base," which can be added to soil to neutralize acidity as well as to increase calcium content. Agricultural liming actually predates the Christian era, and as late as colonial times many farms had kilns in which limestone was converted to lime.
Since lime is the cheapest base available, it has even been used to neutralize acid rain. In Sweden, where the acid-rain problem is particularly serious, the "liming" of lakes is common. Acid rain is caused mostly by industrial emissions of sulfur dioxide, a gas that can combine with water to form sulfuric acid. The problem is greatly reduced if the sulfur dioxide is destroyed by spraying a lime solution into a chamber through which effluent gases pass before being released into the air.
The largest consumer of lime, however, is the steel industry, which uses it to remove impurities such as silicon dioxide from the metal. Lime has also been a component of cement for thousands of years. The Great Wall of China, the Appian Way, and the Temple of Apollo were all built with lime cement. We still use the substance today.
At water-treatment plants, large amounts of lime are used to reduce water "hardness." Adding lime to the water causes dissolved magnesium bicarbonate and calcium bicarbonate (the "hardness" minerals) to precipitate out as magnesium carbonate and calcium carbonate. The water "softened" by this process will not allow soap scum to form.
Lime even has a nutritional aspect. In Mexico, tortillas are traditionally made by soaking corn kernels in lime water until they become soft enough to be pounded into flour. This not only increases the calcium content of a person's diet, but it also improves the flavor of the tortillas. If the process is changed, the tortillas just don't taste right. Today we know why: they are missing 2-aminoacetophenone, a compound that is formed when lime reacts with the amino acid tryptophan and that is so flavor intensive it is detectable at the unbelievably low concentration of two parts per billion.
In Papua New Guinea, India, and Southeast Asia, lime is used in a more unusual fashion. Here, the chewing of betel nuts is a popular pastime. The nuts contain arecoline, a compound that can produce euphoric effects, and the euphoria is more intense if the nuts are chewed with lime. Apparently, arecoline is more active under alkaline conditions. Unfortunately, the strongly alkaline conditions can also cause oral cancers: oral squamous cell cancer is the most common type of malignancy in Papua New Guinea.
Lime has even been used in glue manufacture. Casein, a protein in whey, reacts with lime to form insoluble calcium caseinate, a substance used to glue wooden airplane parts together during the 1930s. The glue was sold as a white powder consisting of whey, caustic soda (for solubilization), and lime. In a sterile world it would have been a perfect glue, but, like cheese, it softens when degraded by microbes. Soft, like Camembert, the glue ran out of the joints.
Although the applications of calcium oxide are interesting, I've always been amazed by the amount of heat released when lime reacts with water to produce "slaked lime," or calcium hydroxide. This reaction is so exothermic that it can produce temperatures as high as 700 degrees Celsius. For this reason, lime has to be kept completely dry while in storage. If it comes into contact with water, a fire may result — wooden sailing ships occasionally caught fire when water leaked into the hold where lime was stored.
But the most unusual lime story involves kitten urine. A few years ago, fire destroyed a Japanese farmer's shed. It seems he had been storing a bag of lime he intended to use for soil improvement there. Initially, no cause for the fire could be found, but a couple of kittens were discovered next to the bag of lime. They had met an unfortunate end; apparently, they'd answered nature's call in the wrong place.
Boyle's Law and a High-Flying Elmo
I had an amusing little encounter with a prospective scientist last time I was flying home from Toronto. Sitting next to me was a small boy who was playing with several bags of peanuts, the bribe he'd extracted from the flight attendant in return for being quiet during the flight.
The boy played happily with the unopened bags throughout the journey, but his face took on a perplexed expression as we landed. The bags had noticeably decreased in volume, prompting the youngster to ask his mother where the peanuts had gone. She had no answer and told her son to stop asking so many silly questions. The lady was obviously unaware of Boyle's Law.
Robert Boyle was born in 1627, in Britain, and was eventually sent off to study at Eton. One evening, while he was outside watching a spectacular display of lightning, he began to wonder why he had not been struck. In a rather unscientific fashion, he concluded that God must have reserved him for some special task. From that moment on, Boyle dedicated himself to demonstrating God's glory by unraveling the secrets of nature.
Boyle became interested in an experiment that had been performed in Germany by Otto von Guericke. In the early part of the seventeenth century, von Guericke had heated a hemispherical copper bowl filled with water until the water boiled. He then fitted a second bowl over the first one, leaving just enough space at the joint to let steam escape. After the heat source was removed, von Guericke discovered that the bowls had become sealed so tightly that two teams of horses couldn't pull them apart. The steam had driven out the air, and when the steam inside the sphere condensed back into a liquid, a partial vacuum was created. The two hemispheres were now held together by the outside air pressure.
All this may sound a little complicated, but the fact is that most of us have carried out a version of this classic experiment in our kitchens. If you remove the lid from a boiling pot and place it on the counter, you'll likely find that it sticks like glue. The trapped steam condenses and creates a vacuum. It isn't surprising that Boyle was fascinated by this effect and was inspired to study the relationship between air and pressure.
Boyle's classic experiment was a marvel of simplicity. He took a J-shaped tube sealed at the short end and proceeded to trap air inside by filling the tube with mercury. He found that the volume of the trapped air varied with the amount of mercury he used and formulated the law that is now studied by every high-school student around the world: the volume of a gas is proportional to the pressure exerted on that gas.
This is exactly what my young traveling companion had experienced. As the airplane gained altitude and the pressure in the cabin decreased, the volume of the peanut package increased. On landing, he could observe the reverse effect.
I didn't feel it was my role to enlighten the young man and his mother about the subtleties of Boyle's law, but this was not the case when I took my daughter to see Sesame Street Live. Needless to say, such an outing involved the purchase of a souvenir — in this case, a helium-filled Mylar balloon in the shape of Elmo. Also needless to say, the balloon didn't make it back to the car. Its escape into the great beyond of course elicited tears, but it also prompted a question about what would now happen to Elmo. And this was not such an easy question to answer.
If the balloon had been made of rubber, it would have expanded in size as it floated up in response to the decreasing outside pressure. But temperature decreases with altitude, and gases contract with lower temperatures; this effect may then be expected to shrink the balloon. We therefore have two factors working in opposition. Calculations, however, show that the expansion due to reduced pressure is more significant, and that as the balloon rises it should eventually burst.
This was probably not the fate of the Elmo balloon. Mylar is made of polyester coated with a thin layer of aluminum. It was originally developed to serve as a heat-reflective material in the space program. Mylar does not have elastic properties, but it is extremely strong — so Elmo could rise to great heights without bursting.
In all likelihood, the helium would eventually diffuse through the plastic membrane, and the collapsed balloon would fall back to earth. This, while certainly a comforting thought, did not nix the demand for a replacement Elmo: Elmo number two still exists and is adored, although it is in rather anemic shape due to the loss of helium by diffusion.
Boyle's law has some unusual connections as well. The New England Journal of Medicine reports that a lady tourist showed up in the emergency room of a hospital in Frisco, Colorado, complaining of a "swishing" sound in her breasts. X-rays quickly revealed the source of the problem. It seems that the patient had a saline breast implant, which is basically a plastic bag filled with saltwater. Such implants, however, are not completely filled with water and therefore have air pockets. The lady had come to high-altitude Colorado from sea level, and, according to Boyle's law, the air pockets had expanded due to the lower external pressure. The water inside now had room to swish around.
This is a true story, unlike the tale going around about the flight attendant who purchased an inflatable bra and experienced an explosion after takeoff. Although such devices do exist, the small change in volume due to a decrease in cabin pressure is not enough to cause such a spectacular effect. The story is an urban myth that deserves to be deflated.
"Der Schwarzer Berthold"
The inscription on the monument that dominates the town square in Freiburg, Germany, reads simply "Berthold Schwarz." Berthold, the legendary father of gunpowder, is one of my favorite scientists. Constantin Anklintzen assumed the name Berthold when he joined the Franciscan order of monks sometime in the thirteenth century. Because of his interest in black magic, his fellow monks began calling him Black Berthold, or "Der Schwarzer Berthold." He was not, in fact, as much interested in black magic as he was in "black powder," although surely at that time the properties of black powder must have seemed very magical indeed.
Black powder was the earliest form of gunpowder and, according to legend, was introduced into Europe by Schwarz. While this is impossible to confirm — the Franciscan records in Freiburg have long since been destroyed — some historians claim the reason we cannot find any authentication of Berthold's existence is that his name was stricken from all records because he was reputed to have compounded gunpowder with Satan's blessing.
Whether Berthold Schwarz actually lived or not will remain a mystery, but one thing is certain: he did not invent gunpowder. Various formulations based on saltpeter, sulfur, and charcoal were known and used long before the thirteenth century. Credit for the discovery rightly goes to the Chinese alchemists who, three hundred years earlier, published a manuscript describing the flammability of this mixture. They probably made their discovery in the course of their search for elixirs that would guarantee immortality. Taoist philosophy dictated that immortality could be achieved if the opposing forces of yin and yang were brought into perfect harmony within the body. Saltpeter was believed to be rich in yin, and sulfur and charcoal were thought to impart yang properties. Actually, saltpeter (potassium nitrate) is rich in oxygen, which allows the sulfur and charcoal to burn.
Excerpted from Radar, Hula Hoops, and Playful Pigs by Joseph A. Schwarcz. Copyright © 1999 ECW Press. Excerpted by permission of ECW PRESS.
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