In connection with these manufactures of different kinds there is a process of great interest; it is that of bleaching: for cloth washed and exposed to the sun and air assume an unwonted whiteness. We are in ignorance as to the origin of this process; but, in some way or other, a certain degree of putrid fermentation was observed to carry off coloring matter from vegetable fibres. The practice must therefore have arisen of macerating cloth in water mixed with putrescent animal matter, which has continued to the present day from the earliest times. The secret was also found out by many nations of antiquity, that natron, the nitre of Scripture, combined with and carried off the coloring matter with which cloth is stained; and the substance is still used for the same purpose. According to Pliny, the ancient Gauls knew the use of a lixivium formed from the ashes of burnt vegetables as a detergent, and also how to combine it with oil so as to form a soap. In one of the tombs of Egypt we have a representation, as the hieroglyphic inscription denotes, of the washing or fulling of cloth. One man is seen rubbing the fabric in a vessel containing some liquid, and another is shaking it out, preparing it for the next process, which is often depicted—its being well wrung out, stretched lengthwise, and fully exposed to the air. Another process of great importance is that of dyeing. It is based on the natural attractiveness of color. How often is the infant’s eye first caught by some bright hue! The blue sky and the verdant carpet of nature have a loveliness for all; while these, with the roseate tints of the morning, the golden sheen of noon, and the rich, empurpled dyes of evening, have furnished epithets freely lavished on the topics they have adorned, by the poets of every age. Even Herodotus says of a nation on the borders of the Caspian—“They have trees whose leaves possess a most singular property; they beat them to powder, and then steep them in water: this forms a dye, with which they paint on their garments figures of animals. The impression is so very strong that it cannot be washed out: it appears to be interwoven with the cloth, and wears as long as the garment.” Strabo, in his account of the Indians, mentions on the authority of Nearchus the various and beautiful dyes with which their cloths were figured. Pliny says of the Egyptians, that they began by painting on white cloth with certain drugs, which in themselves possessed no color, but had the property of attracting or absorbing coloring matters. That these cloths were afterward immersed in a heated dyeing liquor of a uniform color, and yet when removed from it soon after, they were found to be stained with indelible colors, differing from one another according to the nature of the drugs that had been applied to different parts of the stuff.