about 70'F. The caterpillars are black or gray, later turning creamy white, and are interested only in eating. Mulberry leaves, their preferred diet, are supplied to them every three to four hours. After five weeks the caterpillars are 3 inches long and are extremely sensitive to smells or noise; when fullgrown they reject food and become restless, a sign that they are ready to make their cocoons. Small straw frames are then placed on the trays for this purpose. The silk is produced by a pair of tubular spinning glands, each of which secretes a single fiber. One fiber is joined together with the other by muscular contraction, producing a thread up to 300 feet long. A gummy secretion holds it all together in its cocoon shape. This process takes about ten days, after which 90 percent of the cocoons are sent to the factory, while the farmer keeps 10 percent for breeding purposes.

The factory Once at the factory the cocoons are sorted to reject any that are flawed, and the remainder are then steamed to kill the live chrysalis. The threads from six or seven cocoons are needed to produce a fiber strong nough for weaving. The cocoons are immersed in hot ater to loosen the threads, which are then extracted from the water and reeled together as one by machine. The cocoon case left behind is used as an ingredient in traditional medicine. 

The twisting is done mechanically-rows of machines transfer the yarn from one bobbin to another, with each bobbin moving at a different speed in order to achieve the amount of twist required.  From here the silk goes to dyeing factories and then to weaving factories to be made into cloth or carpets, or perhaps to institutes that specialize in the production of silk embroidery. The most famous of these is in Suzhou, and there are others in Guangdong and Sichuan.

Porcelain
Ceramics have a long history in China. During the neolithic period there were two principal types: a red e rthenware, often decorated with black animal and geometric designs, from the Yangshao culture (as seen at Banpo in Xi'an), and black ware from the Loigshan culture.

and fired at a high temperature (the critical feature that distinguishes it from simple pottery) and simultaneously fused with a glaze. Always resonant, the porcelain is sometimes translucent. By the time of the Tang dynasty, porcelain was widely used and exported in enormous quantities, although its method of manufacture remained a mystery outside China until the 18th century. But it was during the Song dynasty that the production of porcelain achieved an artistic elegance that set a precedent not only for subsequent Chinese dynasties but also for the eventual production of porcelain in Europe.

Specialization

During the Song, kilns of different types, both coal-fired and wood-fired, sprang up all over the country and produced both stoneware and porcelain. As production increased, areas began to specialize according to their strengths. In the north, cream-colored porcelain, often with molded designs, predominated, although olive-green or grayish-toned glaze ware, known as celadon, was also produced; in the south, where the best clays were found, a "bluish-white" ware was produced. Production overlapped to some extent, not least because Chinese political life was concentrated in the north until the 12th century, and although each kiln tended to specialize in one type of ware, there is evidence to suggest that they would have produced a quantity of the other types as well. rough out the Song empire, waver, all porcelain was distinctive for its simple elegance and monochrome glazes. The only exception was cream Cizhou ware from Hebei, which was decorated either with narrative painting or deep carving.

Technology During the Mongol (Yuan) dynasty the most important advance was the introduction of blue and white underglaze painting. This used cobalt, imported from the Near East, over a white undercoat of clay, a translucent glaze and high-temperature firing (in excess of 2,335'F). During the Ming dynasty, considered by many the zenith of Chinese porcelain production, the use of underglaze blue and white painting achieved an unsurpassed elegance. There was also a revival of the three-color glazes that were popular during the Tang and the beginnings of overglaze coloring. The latter allowed greater variation since overgiazes were added to the finished product and did not have to endure firing at a high temperature. The new technique permitted a revival in monochromes at the beginning of the Qing, but using rich pastel colors. By the late 19th century, however, design had become heavy and ornate and, although porcelain is still produced in vast quantities today, the elegance of the great dynasties has yet to reassert itself.

EARLY EXPORTS Porcelain began to be exported in earnest during the Tang dynasty. Chinese ceramics from this period have been discovered in places as far afield as Japan, Korea, Borneo, and Egypt. Much was taken by camel along the Silk Road. Al b'lsa, 9th-century governor of Khorosan in Persia (modern Iran), offered over 2,000 porceiain vessels as tribute to the Abbasid caliph, and hundreds of shards have been discovered near Cairo. In AD 851, an Arab merchant noted: "The Chinese make pottery clay vessels as translucent as glass. Wine poured into them can be seen from outside."