He holds 1,093 patents. His inventions ranged from an electric voting machine and the stock ticker to motion picture cameras and the phonograph. He produced the world’s first feature film and first storage battery, perfected kilns to make superior cement, and developed a process for extracting iron ore from the ground. Not bad for someone with only a few months of formal education. And that is all young Thomas Edison had! His mother, infuriated when her son was labeled as “addled” by his first teacher, had resolved to educate the boy at home. Mrs. Edison did a wonderful job, nurturing his love of learning, introducing him to the great works of literature, and encouraging him to study those things that interested him the most. As the man who grew to be perhaps the world’s greatest inventor later said, “My mother was the making of me. She understood me; she let me follow my bent.”
Most people don’t know that young Tom Edison’s first “bent” was chemistry! His passion was triggered by R. G. Parker’s book School of Natural Philosophy, which his mother gave him in 1857, when Edison was ten years old. The book described various experiments that could be done at home, and before long, Tom had built a chemistry lab in his basement. This is where he conducted his legendary experiment with friend Michael Oates. Edison thought that if his friend drank a mixture that would produce a gas in his stomach, he would be able to fly like a gasfilled balloon. Michael, gas and all, stayed put, and got sick. This put a crimp into Tom’s basement chemical investigations for a while, but soon he was back at it, albeit in a different location. On a train! At the age of twelve, young Edison got a job as a newsboy on the train that ran daily from Port Huron to Detroit, but didn’t know what to do during a five-hour layover before the train returned. He had managed to get permission to move the lab from his cellar aboard the baggage car so that he could continue his experiments. Everything was fine until a piece of white phosphorus burst into flame and set the baggage car on fire. The conductor had had enough of Tom’s foolery, and threw him and his chemicals off the train. In spite of this misadventure, Edison never lost his enthusiasm for chemistry, although he did become enchanted with the mechanical and electrical devices that would make his fame and fortune. But even here his chemical interest would come in handy!
Edison’s favorite and most original invention was the phonograph. The earliest version used a needle that moved in response to sound to etch a pattern into tin foil that covered a rotating drum. To play back the recording, the process was reversed. The needle was connected to a diaphragm that vibrated as the needle traced the pattern in the foil, causing the air around the diaphragm to move. Our ears perceive such rhythmic pulsations of air as sound. Edison’s first tinny recording of “Mary Had a Little Lamb,” in 1877, was an astounding breakthrough, but foil was very fragile, and early recordings could be played only a couple of times. A more reliable material was needed, so Edison went back to his chemical roots. Using stearin, the rendered fat of cud-chewing animals, he concocted a wax base of stearic acid, sodium stearate, and aluminum stearate. To achieve the right consistency, he experimented with mixing in various naturally occurring waxes, like carnauba, whale wax, beeswax, or ceresin wax. The components had to be blended together in a heated vat—a dangerous business. One day, in 1899, a batch exploded, leaving Edison swathed in bandages for weeks. He did eventually come up with a mix to manufacture cylinders on which sound could be more permanently recorded. By then Edison had set up his “invention factory” in Menlo Park, New Jersey, where he and his crew of insomniacs doggedly worked on inventions. Modifications such as adding lead and asphalt to the wax yielded better recordings. Edison never gave up trying to improve his cylinders, and eventually switched to the novel plastics celluloid and bakelite.
Edison’s chemical ingenuity was also evident in his electrical endeavors. He had designed a system to distribute electricity, but there was the question of how to charge for the service. Edison was a businessman, reportedly often saying that if an invention could not be sold, he was not interested in it. He knew all about the process of electrolysis, whereby the passage of electricity through a solution can cause substances from solution to plate out on an electrode. So he designed an electric meter that consisted of two copper plates dipped into a solution of copper sulfate. When direct current passed through the solution, one of the copper plates served as the positive electrode, the other as the negative. This meant that positive copper ions from solution were attracted to the negative electrode (cathode), and plated out. At the same time, copper from the positive electrode (anode) dissolved in the solution. The net result was a change in the weight of the plates in proportion to the amount of electricity that passed through the solution.
Meter readers would then periodically come, switch off the power, and remove the copper plates, replacing them with new ones. The used plates were taken away and weighed. On the basis of the change in weight, the customer would be charged for the electricity used. The electric meters were often located in unheated basements, and there was a chance that the solution would freeze. Edison solved the problem neatly. He incorporated a lightbulb into the meter, which produced enough heat to warm up the solution. The bulbs, naturally, were to be bought from Edison’s company. Edison was a clever man.