Ever wonder where old inventions go to die? Some go softly into the good night. Others enjoy long lives as they get repurposed or recycled into new products or services. Legally, this can happen one of three ways. Improvement patents either remove or add something to an existing invention to make it better. Another similar approach is to incorporate new technology into old products. For example, putting a microprocessor into a device previously controlled by analog circuitry can result in a new patent. Finally, it's possible to think of a new use for an existing patent -- something that transforms the first invention into something completely different.
In this article, we'll look at 10 of these "new-use" inventions. Some items on our list have been around for centuries. Others have been introduced only recently. Almost all of them will astonish you with how radically different their new uses are from their original uses. Take the first item on the list: an ancient medicine that proved to be more useful as an agent of murder and mayhem.
Gunpowder, a mixture of saltpeter (potassium nitrate), sulfur and charcoal, has powered fireworks and firearms since the 10th century. But before its big bang as a propelling charge, it started as a substance thought to have medicinal value. The Chinese were the first to toy with the volatile powder in the 8th century B.C. Unlike their Western counterparts, who were on a quest to manufacture gold from base metals, Chinese alchemists hoped to develop an elixir of immortality. They also used gunpowder as a treatment for skin diseases and as an insecticide [source: Robinson].
There's no record of how many people died trying to extend their lives. We do know, however, that a Taoist book from A.D. 850 featured the formula for black powder and warned readers of the dangers of working with the substance [source: Robinson]. Soon after, the Chinese and Arabs were using their elixir of immortality in devices designed to increase mortality, including crude guns made from bamboo tubes reinforced with iron that used a charge of black powder to shoot arrows.
Cows the world over celebrated when John L. Norris introduced Bag Balm -- an ointment used to soothe irritated udders -- in 1899. It proved so effective that farmers began using it to heal the skin ailments of horses, pets and other domestic animals. A few used the salve -- a mixture of petrolatum, lanolin and the antiseptic 8-hydroxyquinoline sulfate -- on their chapped hands.
Over the years, Bag Balm became the duct tape of medicine. It continued to relieve tired teats and painful paws, but it also pacified squeaky springs and lubricated everything from shell casings to the chamois leather in cycling shorts. Then, a small study using Bag Balm to relieve dry skin associated with male pattern baldness showed that some men began to regrow hair where the salve was slathered. This eventually led to a new patent application for the century-old formula. In 2000, the U.S. Court of Appeals for the Federal Circuit declared that using Bag Balm to treat baldness was patentable because it's a new use of a known composition.
In the early 1920s, a mysterious disease caused a large number of cattle to spontaneously bleed to death. Scientists discovered that the affected animals had eaten moldy hay made from sweet clover. When the fungal cells attacked the clover stalks, they produced a powerful anticoagulant. A team of researchers at the University of Wisconsin eventually isolated the chemical, named it dicoumarol and synthesized it in large quantities. Other chemicals in the same class -- all with powerful anticoagulant properties -- soon followed. Warfarin was introduced in 1948 as a rat poison, and it saw widespread use.
It didn't take long for doctors to realize that warfarin might be helpful in patients at risk of blood clots, embolism and stroke. The U.S. Food and Drug Administration (FDA) approved the drug in 1954 for medical use in humans. Today, warfarin is the 11th most prescribed drug in the United States, although its dosing requirements and side effects make it a challenging medicine to dispense [source: Hall]. In October 2010, the FDA approved dabigatran as a replacement for warfarin, which may put the longtime blood thinner back where it started -- in the bellies of rats.
Say the word "Teflon," and you immediately think of nonstick cookware -- those slick, black pans you might use to make perfect pancakes. But that's not the first use of the famous chemical. After Roy J. Plunkett discovered the slippery, inert polymer in 1938, the company he worked for, DuPont, wondered what to do with it. First, the company trademarked its innovation as Teflon in 1945. Then it went in search of a buyer and encountered the U.S. military. Defense officials found Teflon useful in artillery shell fuses and in the production of nuclear material for the Manhattan Project.
After the war, DuPont looked for ways to incorporate Teflon into a consumer product. Developing nonstick cookware seemed like a good idea, but the very thing that made Teflon unique -- its slipperiness -- thwarted chemists trying to adhere the chemical to pots and pans. Finally, in 1954, French engineer Marc Gregoire figured out how to adhere Teflon to aluminum. A year later, he launched the TEFAL (TEF from Teflon and AL from aluminum) Company and began selling the world's first nonstick cookware. Today, DuPont offers its own line of nonstick cookware products, including Teflon Platinum Plus, which holds up to metal utensils.
Ask any astronaut: When you're hurtling toward Earth in an oversized tin can, it's good to have a cushion to help protect your body. The task of developing that cushion fell to a team of aeronautical engineers led by Chiharu Kubokawa and Charles Yost. The scientists eventually invented a pressure-absorbing material, known as visco-elastic polyurethane foam, that could improve conditions for human survival in impacts generating up to 36 G's. Yost called the material "Temper Foam," alluding to its heat-sensitive nature, and began his own company, Dynamic Systems Inc. (DSI), to develop the material commercially. DSI used Temper Foam in a variety of applications, from ejection seats and wheelchair cushions to ski boots and football helmet liners.
Then, in the 1980s, NASA released its patented formula to the public domain. Many companies tried to develop commercial applications using the viscoelastic polyurethane foam, but few were successful. One company that did succeed was Fagerdala World Foams, a Swedish firm that transformed Yost's Temper Foam into the Tempur-Pedic mattress in 1991. Within three years, 50,000 Swedes were going to bed each night on a Tempur-Pedic mattress [source: Funding Universe]. In 1992, North American distribution rights went to a Lexington, Ky., businessman named Bob Trussell. Today, the company is a leading supplier of foam-based mattresses and pillows, with annual sales topping $1 billion in 2010, according to Tempur-Pedic investor relations.
Beyonce and Lady Gaga probably don't worry about it much, but their careers almost never existed because records, record players and the music industry almost didn't exist. Here's the story: After Alexander Graham Bell patented the telephone in 1876, he marketed his invention to businesses. Savvy executives saw the potential of the device as a way to make correspondence more efficient, and phones began appearing in offices and warehouses across the country. There was just one catch -- they didn't have a way to record their conversations.
Enter Thomas Edison, who devised a way to make recordings by allowing sound waves to vibrate a stylus, which in turn etched a groove into tinfoil wrapped around a rotating cylinder. To play back the recording, he passed a needle over the grooves and transmitted the waves through a speaker. Edison quickly packaged his invention into a product -- a telephone message recorder -- that could be sold to commercial operations. Unfortunately, the sound quality was poor, the machines were finicky and businesses lost interest.
The device might have died a slow death if it weren't for other inventors who stepped up to make improvements to Edison's technology. One of these innovators was Emil Berliner, who, in 1887, developed a process to trace sound grooves in a circular pattern on a flat disc rather than on a cylinder. When a negative was made from the flat master disc, it could serve as a mold for making many copies of the original master disc. These "records" could be played on a machine Berliner named a Gramophone, the progenitor of the entire modern music industry.
Many inventions begin their lives in the service of their country, and duct tape is no exception. Military officials tasked researchers at the Permacel division of Johnson & Johnson with developing a tape that would keep ammunition cases dry during World War II. Their solution: a three-ply tape that sandwiched a fabric mesh between a layer of polyethylene on top and a rubber-based adhesive on the bottom. It was exceedingly strong and waterproof, inspiring admirers to call it "duck" tape. It even had the color of ducks -- a drab olive-brown.
After the war, soldiers returned to a booming housing market, and many took jobs on building sites. Recalling the really strong tape from their military days, they recommended it to heating, ventilating and air-conditioning (HVAC) contractors, who needed a reliable adhesive to hold heating and air conditioning ductwork together. Soon, manufacturers started making the tape with a silver-colored polyethylene top so it matched the aluminum ducts.
Today, the usefulness of duct tape extends far beyond the basement. People use it to make everything from handbags and wallets to raincoats and shoes. And, of course, where would impromptu car repairs be without the ubiquitous silver-sided tape to hold sagging mufflers, cover broken windows and hide rusted rocker panels.
OK, pigeons aren't technically an invention, but the idea of using them to deliver messages is a fully human innovation. Genghis Khan, the great Mongol conqueror, used pigeons as messengers in the 12th century, establishing pigeon relay posts across a vast empire that stretched from China to the Black Sea. Using the birds, he was able to transmit messages and instructions more effectively than if he relied on other communications methods.
Messenger pigeons saw action in other military operations, too. In 1937, Lt. Gen. Claire Lee Chennault retired from the U.S. Army Air Corps and flew to China to prepare Chinese bomber and fighter pilots for a Japanese invasion of the mainland. Chennault's Flying Tigers weren't the only birds that took to the air. He also brought hundreds of pigeons, which carried messages during the war effort. Successors of those pigeons still play an important role in the People's Liberation Army.
Now scientists at the University of California, Irvine, are relying on messenger pigeons to collect data about California smog. Each bird receives a tiny backpack containing gas sensors, a GPS and a cell phone to transmit data. Then the researchers carry the birds 20 miles (32 kilometers) out of town and release them. As the pigeons return home, they collect smog information, which is used to generate a pollution map.
Nighttime driving has always presented problems. First came acetylene headlamps in the 1880s and then, by the turn of the century, electric headlights. High and low beams became available in 1917. These innovations certainly made driving at night easier, but there was still a problem: Even with headlights, drivers couldn't easily see pavement markings. In 1935, U.K. inventor Percy Shaw came to the rescue when he introduced cat's eyes, raised pavement markers that shone brightly at night. Each marker contained two glass spheres with mirror-coated back walls. When light rays from a driver's car entered the spheres, they bent and then bounced back toward the driver, following the exact same path.
This process is known as retro-reflection, and traffic signs, bicycle reflectors and high-visibility safety clothing all take advantage of it to improve the experience of night driving. But there are other interesting applications of retro-reflection. In the mid-2000s, scientists at the University of Tokyo invented something called optical camouflage, which relies heavily on a garment made from retro-reflective material. If you were to wear a garment made with this material, you could appear invisible to a viewer standing in front of you by filming an image of what's behind you and projecting it onto the garment. It takes some other fancy equipment, which you can read about in How Invisibility Cloaks Work, but the retro-reflective garment used in optical camouflage is, in essence, an invisibility cloak -- a la Harry Potter.
Watch a sporting event, and you're bound to see a commercial for Viagra, the erectile dysfunction drug marketed by pharmaceutical giant Pfizer. The funny thing is, most people pay attention to those commercials because of the organ Viagra affects and because of the act that organ participates in when it's aroused. If those commercials featured the disease originally targeted by Viagra, far fewer people would probably pay attention.
To see what we mean, rewind back to 1992. That's when a clinical trial began to test the effects of a new drug called sildenafil on 30 men with angina, the chest pain caused by heart disease. The results didn't look promising for sildenafil as a heart medication, but researchers noticed an interesting side effect. Trial participants experienced stronger, longer-lasting erections. As it turned out, sildenafil, which opens up blood vessels, increased blood flow to the penis. Pfizer switched gears and decided to market sildenafil for erectile dysfunction under the brand name Viagra. The U.S. Food and Drug Administration approved the drug for this use in 1998.
Interestingly, researchers are once again hoping to use sildenafil for other conditions other than male impotence. Some studies indicate that the drug could be used to treat high blood pressure in the vessels of the lungs. This condition, known as pulmonary hypertension, often occurs in babies born prematurely. Doctors have treated a few of these babies with Viagra and observed vast improvements in their ability to get oxygen-rich blood from the lungs to other parts of the body. Who knows, it may be possible one day for a person to get Viagra as a baby and then once again as an adult -- to treat two entirely different conditions.
A chemical used in fast food french fries and tire cleaner may cure baldness. HowStuffWorks checks it out.
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