松脂是从松脂油中除去松脂或松脂中的不溶性成分而得到的。它主要由具有一般经验式C20 H30 O2的三环一元羧酸，以及少量可与氢氧化钾或氢氧化钠的沸腾酒精溶液和一些不皂化物质皂化的化合物组成。商业上松香的三大分类是:（1）从活树中采集的松脂中提取的松香； （2） 木松香，从枯木中所含的松脂中提取，如树桩和木节；（3）从塔尔油中提取的塔尔油松香。

Rosin is a natural resin obtained as a vitreous water-insoluble material from pine oleoresin by removal of the volatile oils or from tall oil by the removal of its fatty-acid components. It consists primarily of tricyclic monocarboxylic acids having the general empirical formula C20 H30 O2, with small quantities of compounds saponifiable with a boiling alcoholic solution of potassium or sodium hydroxide and some unsaponifiable matter. The three general classi-fications of rosin in commerce are: (1) gum rosin, obtained from the oleoresin collected from living trees; (2) wood rosin, obtained from the oleoresin contained in dead wood, such as stumps and knots; and (3) tall-oil rosin, obtained from tall oil.