The first emperor of China, Qin Shihuang, accomplished a huge amount during his rule. Between 221 and 210 B.C.,he started the construction of the Great Wall. He built a large network of roads. He introduced a new writing system, currency(货币),and a set of measurement. The emperor also ordered the construction of a huge army of life-sized terracotta soldiers. These, he hoped, would protect his tomb after his death. The soldiers in Xi'an's Emperor Qin shihuang's Mausoleum Site Museum are today （light） brown, but they weren't always. They began as an army of red, blue, yellow, green, white, and purple. Sadly, most of the colors did not last to the present day. After being exposed to air during excavation(挖掘),the coating under the paint began to fall off. The paint disappeared in less time than it takes to boil an egg, taking with it important pieces of history. Now new techniques are starting to reveal the army's true colors. Archaeologists have recently discovered an area with more than a hundred soldiers. Many of them still have their painted features, including black hair, pink faces, and black or brown eyes. Chinese and German researchers have developed a special liquid to help preserve the soldiers" colors. After hey find a soldier or other artifacts(手工艺品),archaeologists spay it with the liquid.They, then, cover it in plastic Archaeologists are also finding colors in the dirt around the soldiers. It's important not to disturb the dirt,so the colors won't be lost."We are treating the earth as an artifact," says archaeologist Rong Bo, the museum's leading chemist. The next challenge, says Rong, is to find a way to apply the colors to the army again. Once that happens, artists can bring Emperor Qin's army back to life in full, vivid color.