According to United States Patent No. 1,800,295, dated April 14, 1931, a resin fast to light and soluble in oils is obtained by heating 82 parts of p-tertiary amyl phenol with 90 parts of formaldehyde, in the presence of sodium hydroxide. This substituted phenol resin passes slowly into the infusible state, thus permitting better control of the reaction. Para tertiary butyl phenol. Para tertiary butyl phenol is a white solid with an aromatic odor, melting at approximately 100° C. It is a new commercial product and is used in resins for paints and varnishes. It is the most important resin material in this group. Phenyl phenols. Both ortho and para phenyl phenol are commercially produced and are used to some extent in resins to replace phenol. The ortho isomer is a white solid boiling at 284° C. and melting at about 56° C. It is used chiefly as a germicide, though small quantities are used in resins. Para phenyl phenol is a white solid melting at about 165° C. and boiling at 322° C. Commercial production was reported for the first time in 1933. The output has increased each year since and the selling price has gradually declined. Resorcinol. Resorcinol, usually obtained by fusing meta benzene disulphonic acid with caustic soda, is a colorless, crystalline substance with a peculiar odor. It melts at 119° C. and boils at 276° C. It is used in medicine, in the manufacture of intermediates and dyes, and to some extent in synthetic resins. Resorcinol condenses with formaldehyde at such a rapid rate that some means must be applied to slow up the reaction. It is used to increase the rate of condensation of tar-acid resins and to reduce the danger of sticking or undercure. Domestic production of resorcinol has decreased in recent years. Its relatively high cost is probably an important factor in limiting its use in synthetic resins. FORMALDEHYDE Description and uses. At ordinary temperature and pressure formaldehyde is a gas. It enters commerce as formalin, an aqueous solution containing 40 percent formaldehyde by volume (37 percent by weight) and from 6 to 14 percent methyl alcohol. It is generally made by the oxidation of methyl alcohol. Commercial formalin contains polymers which tend to precipitate in water solution; these are kept in solution by allowing from 6 to 14 percent methyl alcohol to remain in the solution. The principal use of formaldehyde is in the manufacture of synthetic resins. Other uses are (in the order of their importance): In the manufacture of synthetic indigo; in the manufacture of hydrosulphite; as a disinfectant, deodorant, and preservative; as a fungicide; in embalming fluids; in tanning leather; and in the manufacture of coated paper and wallpaper. United States production.