|Table of Contents for Caveman Chemistry: 28 Projects, from the Creation of Fire to the Production of Plastics|
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The story of Unktomi-Venus is somewhat autobiographical. My wife had gone out shopping and I was left home alone with our German shepherd, Sandy. By the time my wife returned I had several feet of what I considered the finest twine I had ever seen. We will never know the details of the first time someone sat down with a handful of fiber and made string from it, but I have tried to tailor my little story to fit the evidence presented by Elizabeth Wayland Barber in her excellent book Women's Work: The First 20,000 Years, on the early history of textiles. The earliest representations of human clothing depict women of child-bearing age wearing waist-hugging skirts made of what appears to be spun string rather than tanned hide; contemporary images of men are nude. The tradition of spinning was the domain of women up to the time that it began to be industrialized in the Iron Age. Apparently the work of spinning meshed well with that of child-rearing, but there is nothing to prevent the modern reader from learning and enjoying this craft, regardless of gender. As I see it, though inventions originate with particular individuals of particular races and genders, the inventions themselves belong to our common human heritage. Once an inspiration leaves its original home, it's no longer male or female, black or white; it's just a spider in the wind looking for a place to land.
The goal of spinning is to make long fibers from short ones. While any one strand of wool is no more than a couple of inches long, it may be used to make string hundreds or even thousands of feet in length. A beginning spinner may assume that this is accomplished by twisting the fibers together, but as important as twisting is, properly arranging the fibers, drafting them at the point where fiber turns to twine is even more crucial. And in a curious coincidence, the biological synthesis of long fiber molecules from short ones parallels the spinning of string from fiber.
All higher organisms face the problem of getting material from one place to another. Plants send material from the roots to the leaves and back via sap. Animals move nutrients from the stomach to the rest of the body via blood. Both sap and blood are aqueous solutions and so material transport depends on the solubility of the chemicals to be transported. But once they reach their destinations, some of these chemicals must be converted to skin and bone and hair or else the organisms would dissolve in its own juices and slump into a puddle of goo.
Nature discovered long before we did that short, water-soluble monomers can be linked together to make long, insoluble polymers. For plants, the principle monomer is called glucose, the same molecule that's in honey. You already know that glucose dissolves in water, since it is the sugar that is fermented to make mead. The plant makes glucose out of air and water and sunlight in the leaves and sends it all over the plant in the sap. When that glucose gets wherever it's going, the plant chains all those little molecules together, polymerizes them, into one long molecule, cellulose, which is what wood is made out of. The cellulose molecule is so much larger than water molecules that they can't push it around; in other words, cellulose is insoluble in water.
One of the most important classes of polymerization reactions, called condensation, results when a hydrogen atom on one molecule gets together with a hydroxide group on another and leaves as water; Equation 6-1 shows how cellulose condenses from glucose. The n in the equation could be any number at all, one or a thousand or a million, but as in any balanced reaction equation, there are the same number of each kind of atom on both sides of the equal-sign. Also notice that the formula for cellulose is (C6H10O5)n, not CH2O as Lucifer told you. The long formula is called a molecular formula, because it tells you how many atoms are in each molecule. Lucifer introduced you to an empirical formula, one which only tells you the proportions of the different atoms. In glucose, for example, you can divide the molecular formula, C6H12O6, by 6 to determine the empirical formula, CH2O. Now, if you've been paying attention, you'll notice that the empirical formula of cellulose really ought to be C6H10O5, because you can divide the whole molecular formula by n. If you were to try dividing it down further, say, by 5, you would get C1.2H2O, which does not have integer subscripts. Lucifer's formula for cellulose was actually only an approximation so as not to scare you with a big long formula right off the bat. You might want to go back to Equation 1-1 and update it with the correct formula.
Animals use glucose, too, but not for structural purposes. Proteins are the stuff of skin and hair, and they are composed of twenty slightly different monomers, the amino acids, of which, the simplest is glycine, C2H5O2N. When an animal eats meat, the meat is broken down into amino acids in the stomach and these amino acids dissolve in the stomach acid. They get pushed around in the blood to wherever they're going, and when they get there, they are hooked together once more into long protein molecules, which like cellulose, are insoluble in water. Equation 6-2 shows what the condensation reaction would be if you polymerized glycine alone. In reality, proteins are sequences of all twenty different amino acids, and the properties of the protein are determined by the amino acid sequence. But the main idea, the linking of small things into big ones is common to all living things, and so is at the heart of making textiles on both the microscopic and macroscopic scales.
I think it would be fairly difficult to hurt yourself making string. I suppose you could jab a drop spindle into your eye or something, so don't do that. Chemically speaking, wool has so many different things in it, different amino acids and grease and whatnot, that you won't be able to find an MSDS for it. But you should get used to thinking about hazardous materials as a matter of course. Sheep produce lanolin to make their coats water-proof and since lanolin is a component of many hand creams, spinning "in the grease" will leave your hands soft, supple, and farm fresh. Raw wool will also contain dingle-berries and urine, and given the propensity of bacteria to reproduce, it would be a good idea to wash your hands after spinning.
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If you are in a class, you might want to know what will be on the quiz.