CRUDE DRUGS. 653 



COLOPHONY. ROSIN OR RESIN. The residue after 

 the distillation of the crude oleo-resin (or turpentine) of 

 Pimis pahistris and other species of Pinus (Earn. Coniferae), 

 evergreen trees (Fig. 47, B) indigenous to the Southern United 

 States (p. 81). There are two commercial varieties of Colo- 

 phony : ( I ) one which is amber colored and derived from the 

 oleo-resin of trees tapped for the first time; and (2) a yellowish- 

 red or reddish-brown variety derived from the oleo-resin of trees 

 that have been tapped for a number of years. The former kind 

 is preferred. 



Description. Usually in sharp, angular fragments ; trans- 

 lucent, amber-colored, usually covered with a yellowish dust, hard, 

 brittle, pulverizable, fracture shiny and shallow-conchoidal ; odor 

 and taste faintly terebinthinate. 



Resin has a specific gravity of 1.070 to 1.080, and it is soluble 

 in alcohol, ether, benzol, carbon disulphide, acetic acid, fixed and 

 volatile oils and in solutions of potassium or sodium hydrate. 



On heating a small quantity of colophony and neutral methyl 

 sulphate or neutral ethyl sulphate in a test-tube the mixture 

 assumes a rose, then violet and finally a deep violet color. 



Constituents. From 80 to 90 per cent, of an anhydride of 

 abietic acid, which on treatment with alcohol is changed into 

 abietic acid, which latter is crystalline ; sylvic acid, which is prob- 

 ably a decomposition product of abietic acid ; ash, about i per cent. 



White rosin, prepared by agitating melted rosin in water, 

 occurs in whitish, opaque masses, due to inclusion of air. 



Rosin is not infrequently used as an adulterant of other resin- 

 ous products, as of Burgundy pitch and Venice turpentine. A 

 mixture of rosin and oil of turpentine is sometimes substituted 

 for the latter. 



Resins are a class of substances which may be looked upon 

 as final products in destructive metabolism. They result from the 

 oxidation of oils and allied products and usually accompany them, 

 as oleo-resins, gum-resins, etc. They are insoluble in water, solu- 

 ble in alcohol, acetone, ether and similar solvents, and burn with a 

 yellow flame, forming considerable soot. Several kinds of 

 resins are recognized, depending upon the nature and constitution 

 of their important constituents : 



