_Raw materials._—Although the chief raw materials consumed in the synthetic resin industry are coal-tar derivatives and formaldehyde, many others are utilized. The rapid expansion of the industry has created new demands for materials in increasing quantities and has not only increased the markets for well-known materials but has resulted in the production on a huge scale of materials entirely new to commerce. Practically all the raw materials now used can be derived from a few natural substances, such as air, water, coal, petroleum crudes, salt, sulphur, and limestone. The air yields nitrogen which may be converted to ammonia, a raw material for urea, one of the components of the urea resins. Coal, as is well known, yields a great variety of substances, many of which are essential to synthetic resin manufacture. Benzene is the starting point for synthetic phenol; naphthalene is used to make phthalic anhydride and maleic anhydride; coke is converted to calcium carbide, which in turn yields acetylene, acetic acid, and many other synthetics; carbon monoxide which is converted to methanol and formaldehyde; and the natural tar acids such as phenol, the cresols, and the xylenols. Limestone is a component of calcium carbide, and salt yields needed alkalies and acids. Water is broken down, and the hydrogen is converted to ammonia, methanol, formaldehyde, and ethylene. Some idea of the expansion in production of these raw materials whose principal use is in synthetic resins may be had by comparing the output in 1923 of tar acids, formaldehyde, phthalic anhydride, maleic anhydride, urea, vinyl acetate, and vinyl chloride, which amounted to 35 million pounds, with the output of 270 million pounds in 1936. The manufacture of these materials is largely by coal-tar distilling companies and makers of chemicals. _Resins._—The coal-tar resins are the most important in quantity, value, and variety of application. This class includes four groups: (_a_) tar acid, (_b_) alkyd, (_c_) coumarone and indene, and (_d_) polystyrene. Of these, resins from tar acids (phenol, cresols, and xylenols) are produced in the largest quantity, the output having increased from about 15 million pounds in 1932 to about 80 million pounds in 1937. In the latter year about 40 percent of the consumption of tar acid resins was in molded articles, 25 percent in paint and varnishes, 20 percent in laminated products, and 15 percent in miscellaneous uses. The alkyd resins have shown a remarkable increase in output. Production totaled slightly less than 10 million pounds in 1933; in 1937 it amounted to about 61 million pounds. Practically all of the alkyds have been consumed in paints and varnishes. The coumarone and indene resins have increased steadily over a number of years and are now one of the most important groups.