Look through the text and complete the gaps.

Materials That Changed History

Where would we be without wood, ceramics, glass, iron? Here, look at 10 materials that were very important for humanity, ranging from the most ancient ones to the 21st century.

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Before stone there was wood. We humans are, after all, products of the forests. Our material world was once one of logs, sticks, bamboo, and many other forms that wood takes in nature.

Wood allowed humans to transform rivers and seas from barriers to highways; to build fences, homes, and walls, even when little stone was available; and to furnish their lives with everything from beds and chairs to buckets and barrels. In the last century wood extended to new forms, including slices, laminates, particles, and chips.

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In the 21st century, we don’t think much about pots made from fired clay. But back in the times, ceramics was one of indicators of a society's development. An "aceramic" society had few ways of storing food or water, and thus its agriculture was limited and primitive.

Clay can be shaped and then hardened by drying, but only when it is baked to high temperatures, it can keep its shape over a range of conditions. Combining clays with other minerals and then firing the mixture resulted in brilliant colors.

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While a limited number of "fibers" exist in nature, there is no cloth. And the fibers that do exist—silk, cotton, or wool, for example—have to be transformed before they can be made into cloth. How humans learned to take the hair of a sheep or goat and twist hundreds or thousands of individual hairs together to make wools is one of the great mysteries of our early history.

The variety of cloth has not stopped the application of modern chemistry. While some of the earlier efforts at fashioning clothing from synthetic materials such as polyester became jokes, today it is a rare wardrobe that does not feature some cloth whose history began in a test tube rather than on a farm.

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The first metal that humans could make use of was copper. But bronze, an alloy of copper with small amounts of tin, is a much more useful form.

As the first alloy, bronze started the use of metals, mainly for weapons. The first swords had bronze blades with sharp edges.

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Even in the 21st century, no more important metal exists than iron, and this has been true for as much as 3,000 years. Workable ores of iron are in almost every part of the world, and different techniques can produce forms of the metal with a great range of properties.

For the last century and half, the most important form of iron has been steel. Steel is actually a great range of materials, whose properties depend both on the amount of carbon contained—typically between 0.5 and 2 percent—and on other alloying materials.

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The first glass was probably made by accident, as sand found its way into an oven and then melted. While we think of glass as normally clear, it took centuries of experience and experiment to produce a clear glass.

Glass is made by heating sand with a "flux," which is a mineral that will lower the melting point of the mixture.

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Humans tried to write for thousands of years before they had paper—writing can be put onto stone, clay, wood, cloth, skin, and other surfaces. But even with so many alternatives and electronic media, a world without paper would be very different.

Paper is one of a number of inventions that came out in China about 2,000 years ago.

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For thousands of years, people liked a small number of materials distinguished by their appearance: ivory, tortoiseshell, and horn were luxury items. In the 1800s, the growth of markets and understanding of chemistry made it possible to produce such items in great quantities at low cost. The first commercial plastic was celluloid, made from nitrated cotton and camphor. When this combination was heated under pressure, it was made into everything from combs to dolls and ping pong balls.

Closely related to plastics was rubber, which started out as a natural product brought to Europe from South America. The Europeans adapted the production techniques.

Words:
Ceramics. paper. glass. bronze. iron and steel, fiber and cloth, wood, plastics and rubber