1847 C. Morfit xv. 131 The formation of yellow soap from resin, depends on the direct combination of the resin acids with soda.
1922 J. J. Sudborough (new ed.) xlii. 631 Amber is a fossil resin which contains succinic acid in addition to resin-acids and a volatile oil.
1991 2 Nov. 19/3 The caterpillars which fed on pine needles with a high content of resin acid produced larger and more viscous droplets.