Combustion Is Anything but Ordinary
Editor’s note: We are pleased to present a series adapted from biologist Michael Denton’s book, Fire-Maker: How Humans Were Designed to Harness Fire and Transform Our Planet, from Discovery Institute Press. Find the whole series here. Dr. Denton’s forthcoming book, The Miracle of the Cell, will be published in September.
Of course, human determination, inventiveness, and sheer genius played a major role in the development of technology. But this is only part of the story. On even the most cursory reading, the march of technological advance from the Stone Age to Curiosity was only possible because of what would appear to be an outrageously fortuitous set of environmental conditions, without which, despite our genius, we would still be hunter-gatherers and, as Alfred Russell Wallace noted a century ago, no advance beyond the most primitive stone tools would have been possible.1 In short, in the development of technology, nature lent a hand.
The combustion of wood or coal may seem so familiar as to be unworthy of any comment. But combustion — the reaction between reduced carbon (in wood, coal, or charcoal) and oxygen — is anything but ordinary. On the contrary, it is a unique chemical reaction, providing enormous energy and heat to perform many useful tasks while at the same time being non-explosive and readily controlled. The relative lethargy of the reaction between oxygen and carbon — witnessed in the difficulty of starting a campfire — is the result of unique features of both the oxygen atom and carbon atom,2 which renders them peculiarly unreactive at ambient temperatures.
This low chemical reactivity allows for the safe and controlled use of fire. It also means that we do not spontaneously combust at ambient temperatures in the current atmosphere of 21 percent oxygen. And because of the curious un-reactivity of the oxygen atom at ambient temperatures, oxygen must be activated to utilize its energetic potential: in the body by special catalytic processes and in wood through the application of heat.
Adding Fortuity to Fortuity
Moreover, as I mentioned earlier, it is only because charcoal reacts more vigorously with oxygen than uncooked wood, making possible the high temperatures in kilns and furnaces, that the extraction of metals from their ores and the development of metallurgy was possible at all. And adding fortuity to fortuity, burning charcoal not only provides the necessary heat but also the reducing conditions in the kiln that strips the oxygen from metal ores, an essential element in the smelting and metallurgy of iron.3 As Arthur Wilson notes: “It was a fortunate coincidence that the fuel that primitive man used to generate heat [sufficient to smelt metals] was also an effective chemical agent for reducing oxidized ores to the metallic state.”4 (Emphasis added.)
The fact that the same substance, charcoal, provides the source of heat for smelting metals and the reducing conditions in the kiln necessary strip oxygen from metal ores is another unique and crucial element of fitness which made the development of metallurgy possible. It is very difficult to imagine how the essential reducing atmosphere in the kiln could be achieved in any other way. And there are yet other elements of fitness of charcoal for metallurgy. Being porous, charcoal enables the blacksmith to regulate the temperature in the kiln by changing the flow of air through the bellows.5
It is certainly an intriguing element of fitness in nature that, although ordinary wood fires do not generate sufficient heat to smelt copper or iron, charcoal “was one way in which nature came to the rescue of the early metal workers.”6 As mentioned above, burning charcoal in a vented kiln can generate temperatures well above 1,000° C, sufficiently high for extracting these two key metals from their ores. Given the range of temperatures in the cosmos and the fantastic diversity of the properties of matter, it beggars belief that the smelting temperatures of metal ores are in reach of the temperatures that can be generated in wood or charcoal fires — a coincidence upon which the whole subsequent development of technology depended.
Tomorrow, “The Path to Technology Was Built in Nature.”
- Alfred Russel Wallace, The World of Life (London: Chapman and Hall, 1910), 359-361.
- Witnessed in the unreactivity of soot, graphite, and coal. See Nevil Vincent Sidgwick, The Chemical Elements and their Compounds, vol. 1 (Oxford: Oxford University Press, 1950), 490.
- Wilson, 11.
- “Charcoal,” Wikpedia, May 12, 2016, accessed May 17, 2016, https://en.wikipedia.org/wiki/Charcoal.
- King, “Early Bronze and Copper Technology From the Dawn of History Until Early Historic Times (2000 B.C.-400 B.C.),” Roman History, Coins, and Technology Backpages, 2006, accessed May 18, 2016, http://www.jaysromanhistory.com/romeweb/glossary/timeln/t09.htm: “Nature did work in one way to favor the early metalsmiths… Charcoal is produced as part of the burning process. This natural tendency of a fire to produce essentially pure carbon is the one way in which nature came to the rescue of the early metalworkers, for pure carbon is the only fuel the ancients had available to them that could even come close to producing the temperatures needed to smelt metals. Pure carbon will burn quite hotly in the presence of a forced air draft… While a fire burning naturally will produce mostly carbon dioxide and ash, with a little carbon monoxide, a forced fire will produce greatly increased quantities of super hot carbon monoxide [an excellent reducing agent which draws the oxygen from the metal ore].” (Emphasis added.)