Crude grades, melting between 70° and 78.5° C., are found in commerce as yellow, red, or brown crystalline solids. These grades are used in the manufacture of phthalic anhydride and other coal-tar intermediates; in the manufacture of lampblack; to enrich illuminating gas and sometimes motor fuel; in synthetic tanning materials; and in certain insecticides. Probably its most important outlets are as a raw material for phthalic anhydride (see p. 98) and refined naphthalene. Refined grades, melting above 79° C., are marketed as white, crystalline lumps or flakes. Their principal uses are in the manufacture of intermediates, dyes, medicinals, solvents, and textile assistants; as moth repellants; as a lubricant when mixed with rapeseed oil; to remove the “bloom” from lubricating oils; as a preservative for rubber goods and animal skins; and in explosives (trinitro naphthalene). In 1936 more than 75 coal-tar intermediates made from naphthalene were commercially produced in the United States. Of the 75 million pounds of these intermediates produced in that year, 31 million pounds were phthalic anhydride, an important component of synthetic resins of the alkyd type. United States production. Crude naphthalene is produced in the United States by byproduct coke-oven operators, gas works that produce their own coal tar, and also by firms that purchase coal tar and distill it. Statistics of production by groups are shown in table 33. TABLE 33.—_Crude naphthalene: United States production, 1918-37_