RESIN OF TURPENTINE. 889 



chlorine. Fused by heat, and exposed again to chlorine chloro- 

 colophene absorbs that gas, and emits a large quantity of hydro- 

 chloric acid, giving a new product, of a transparent yellow 

 colour, which may be represented by C 40 H 24 C1 8 . 



It thus appears that four isomeric oils exist related to the 

 essence of turpentine, of which the common formula is C 20 H 16 , 

 namely camphene, terebene with camphilene and terebilene, the 

 two latter being obtained by similar processes from the two 

 former ; also another pair, of which the atomic weight is double 

 and the formula C 40 H 32 , namely colophene and colophilene ; 

 and that each of these bodies gives rise to a particular series of 

 compounds by uniting with hydrochloric acid, chlorine, &c. 

 (Deville, An. de Chim. Ixxv, 37). 



COLOPHONY, OR RESIN OF TURPENTINE. 



Common turpentine affords when distilled with water from 

 5 to 25 per cent of essence, what remains being common resin, 

 named colophony, or colophonium, of which the composition 

 generally received is C 40 H 32 O 4 (Rose) ; that is, 2 equivalents of 

 the essence combined with 4 equivalents of oxygen. M. Liebig 

 is disposed, from more recent analyses, to represent the resin 

 by C 40 H 30 O 4 , and then in its formation, the essence C 40 H 32 

 loses 2 atoms of hydrogen, which are replaced by 4 atoms of 

 oxygen. The resin is not, however, a homogeneous product, 

 but was divided by M. Unverdorben into two different resins, 

 which he named sylvic and pinic acids. The properties of the 

 mixture of these resins or colophony are familiar ; it is a yel- 

 lowish brown, translucent, brittle solid, fusible, readily soluble 

 in alcohol, ether, the fixed and volatile oils ; soluble in alkaline 

 leys, with which it combines as an acid, and forms soluble salts, 

 which are detergent, and enter largely into the composition of 

 all brown soaps. The two resins are separated from each 

 other by means of cold alcohol, of 72 per cent (sp. gr. 0.86'7), 

 which dissolves pinic acid, or alpha-resin as it is also called, 

 and leaves behind sylvic acid, or beta-resin. 



Alpha- resin (pinic acid), is precipitated from the alcoholic 

 solution by water ; it is not crystallizable ; after being fused, it 

 has quite the appearance of colophony ; it is insoluble in water, 

 but dissolves easily in alcohol, ether, and oil of turpentine ; 



