718 PROPERTIES, HARVESTING AND DISPOSAL OF RESIN. 



The timber is cut mainly into railway-sleepers and pit-props, 

 which latter are exported chiefly to England. 



The French forest officials do not consider that 60 years is a 

 long enough rotation to get the full benefit from the forest, 

 especially in timber, and it is proposed to lengthen it to 75 

 years, with 15 compartments. 



Private forests of maritime pine near Arcachon are managed 

 chiefly for the yield of resin, and consequently are tapped 

 younger and more severely than are the State forests. 



Boppe estimates that in a private maritime pine forest, 45 

 years old, each tree will yield 6J to 10 pounds of crude resin 

 per annum. The yield per acre varies greatly, according to the 

 nature of the soil and the management ; 250 to 450 pounds 

 per acre per annum are given as the extremes. The value 

 of the casks of resin containing 235 kilogram (625 pounds) 

 was 40 to 45 francs in 1885, but only 30 to 35 francs in 1894. 



One of the reasons for the variation in price is that the 

 spring-crop of resin is much lighter-coloured and freer from 

 impurities than the autumn-crop, in which barras is added by 

 the workman to the extent of 50 kilograms per cask. 



The chief dangers in the forests of maritime pine are fires 

 and invasions of shifting sand, the protective measures 

 against which are described in Vols. II. and IV. of this 

 manual. 



B. TAPPING OTHER SPECIES FOB KESIN. 

 1. Silver-fir. 



Most of the crude resin in the silver-fir is contained in its 

 bark, where a few drops of resin accumulate in little project- 

 ing blisters. It is collected by pressing these blisters with 

 the sharp nozzle of a small tin vessel. This practice, which 

 yields little and is being abandoned gradually, produces 

 Strasburg resin. 



2. Spruce.* 



The spruce is tapped for resin by cutting long narrow 

 grooves (3 to 6 centimeters broad and 1 to 1*5 meter long) 



* [This account is taken from Gayer. Tr.] 



