RESINOUS PRODUCTS. 93 



the paint to dry rapidly. Colophony is the solid matter that remains 

 after the separation of the oil of turpentine ; its chemical formula is 

 CM H 10 2 ; it differs in appearance and properties according to the 

 amount of impurities contained in it ; the best colophony is brownish 

 yellow, crystallises in small rhombic prisms, is insoluble in water, but 

 is dissolved in alcohol ; it is a non-conductor of electricity, and 

 in its fossil state it is known as amber. 



The principal seats of the resin industry are: (1) Districts around 

 Bordeaux in France which are covered with plantations of Finns Pinaster \ 

 (2) in the north of Italy on a much smaller scale where Venetian turpen- 

 tine is prepared from the resinous secretions of the common Larch ; (3) 

 in southern Norway and Sweden where the coarser products as tar and 

 pitch are procured from Pinus sylvestris; (4) in the Pine Barrens 

 of the southern States of North America, the source of the greater 

 part of the turpentine of British commerce, which is obtained from 

 Pinus palustris and P. Tceda ; and (5) on the outer or sub-tropical 

 Himalayan zone where the Indian supply is obtained from Pinus 

 longifolia. The modus operandi of collecting the crude resin in each 

 region is different, and is attended with widely different results. 

 In the south of France the processes employed are conducted with 

 the greatest economy of material with a minimum of injury to the 

 trees, so far as the nature of the operation admits. In Georgia and 

 South Carolina the aim of the resin-collectors is to obtain the greatest 

 amount of crude resin with the smallest expenditure of labour and 

 time, without any regard to the fate of the trees they attack. A 

 comparison of the two methods is highly instructive. 



French method. Towards the end of February the rough outer bark of 

 the maritime Pine, Pinus Pinaster, is trimmed off at the place intended 

 to be tapped, so that only a thin layer of bark is left covering the sap- 

 wood, the part of the tree in which the resin is most abundant. Early 

 in March an incision is made in the shape of a longitudinal groove of 

 small dimensions by a special instrument called an abchotte, much 

 resembling a carpenter's adze but smaller. The resin trickles through the 

 orifice thus made in drops which thicken in contact with the air; one 

 portion of it solidifies and adheres to the surface of the groove, the 

 remainder flows into a vessel placed below to receive it. The resin ceases. 

 to exude about the middle of October when the collecting ceases, but it 

 is renewed in the following March and continued for several years > 

 usually about five, from the same trees ; the trees are then left for two- 

 or more years untouched when the collecting is renewed from a fresh 

 incision ; by this metliod the trees retain their vigour for many years and 

 their timber is not impaired. Once a week the groove is freshly cut by 

 slicing off a thin shaving from the upper side, so that whilst the groove 

 becomes gradually longer, its width remains unaltered. 



The crude resin is collected in earthen pots varnished on the inside, 

 placed at the lower end of the groove and held by means of a zinc collar 

 fixed across it. As the pot becomes filled, the collector empties it into a 



