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Carbon Black: From Copying to
Communication
Andrew R. Barron
This work is produced by The Connexions Project and licensed under the Creative Commons Attribution License †
It is a commonly held fallacy that James Watt (Figure 1) was the inventor of the steam engine. This actually honor belongs to Thomas Newcomen (Figure 2). Watt's actual achievement was to improve New- comen's design of a steam pump. While Watt was working in the repair shop at the University of Glasgow he was xing a Newcomen pump when he developed several key improvements on the original design.
Figure 1: Scottish inventor and mechanical engineer James Watt FRS (1736 1819).
∗Version 1.1: Sep 28, 2009 9:24 am GMT- †http://creativecommons.org/licenses/by/3.0/
Figure 2: English ironmonger and inventor of the steam engine Thomas Newcomen (1664 - 1729).
The reason for Watt's success was that Britain was going through a major industrial boom and was in need of signi cant quantities of raw material including coal. Many of the coalmines, especially those in Devon were prone to ooding. Unfortunately, Newcomen's engine (which was actually a steam pump) could not pump the water out fast enough, whereas Watt's engine was powerful enough to drain the mines. As a result Watt's career as a manufacturer was assured. However, Watt did not see the full potential of his invention, this was left to an employee of his, William Murdock (Figure 3), whose invention of the gearing to allow the steam engine to be used for powering machinery.
Figure 3: Scottish engineer and inventor William Murdock (1754 - 1839).
One outcome that Watt found from his increased business was an increase in paperwork! While he was living in Redruth, Cornwall, close to where many of the mines were situated he told a friend that he
note: The term CC commonly used in e-mail programs today grew from the use of carbon paper and means carbon copy.
Interestingly, carbon black is still used today in modern photocopiers and laser printers. One of the attributes that allow its use is the ability for carbon black particles to become charged. This is related to another application of carbon black in early communications: its ability to conduct electric, and the changes that occur as a function of external pressure. While Alexander Graham Bell was the rst to be awarded a US patent for the electric telephone in March 1876, it was an invention by Thomas Edison (Figure 5) that provided signi cant improvements. Early telephones relied on a metal diaphragm that was attached to an electromagnet. Speaking into the metal diaphragm caused its vibration, which in tern vibrated the electromagnetic and hence created a current. Unfortunately, the current was very low and subsequent clarity was poor. Between 1877 and 1878 Edison investigated methods to improve the clarity of the signal. The key development was the carbon microphone (Figure 6).
Figure 5: American inventor, scientist and businessman Thomas Alva Edison (1847 1931).
Figure 6: A schematic of a simple carbon button microphone.
The carbon microphone, also known as a carbon button microphone consisting of two metal plates separated by granules of carbon. One plate faces outward and acts as a diaphragm. When sound waves strike this plate, the pressure on the granules changes, which in turn changes the electrical resistance between the plates. A direct current is passed from one plate to the other, and the changing resistance results in a changing current, which can be passed through a telephone system. The carbon microphone was used in all telephones until the 1980s. It was one of Edison's researchers, Edward Acheson (Figure 7) whose discovery allowed for the extension of communication on a global scale. While trying to make arti cial diamonds, Acheson began mixing clay and coke (carbon) at very high temperatures. In an electric furnace at high temperatures he found hexagonal crystals of silicon carbide (SiC) attached to the carbon electrode. He called this material carborundum. When, by mistake, he overheated the mixture to 4150 ◦C he found that the silicon evaporated (boiling point 3265 ◦C) leaving pure and highly crystalline carbon: graphite.
Figure 8: German geologist Abraham Gottlob Werner (1749 1817).
The V-2 rockets or Vergeltungswaen-2 (vengeance weapon-2) was 47 feet long, and reached 3,600 mph with an altitude of 300,000 feet (Figure 9). In order to control the direction of ight the V-2 was guided by four external rudders on the tail ns, and four internal vanes at the exit of the jet (Figure 10). These vanes were made of graphite, it being the only material that would survive the extreme temperatures.
Figure 9: A V-2 rocket at the Peenemu¨nde Museum.
Figure 10: View of the V-2 rocket showing the graphite vanes for directional control.
Of course it was as a result of the same German scientists who worked on the V-2, working for NASA, that allowed rockets of su cient power to escape the Earth's gravitational pull and send man to the moon, and position many of the satellites that are now vital for global communication.
