644 K ESI N -TAPPING. 



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

 lonj; cnouy:h rotjition to get the full benefit from the forest, especially 

 in tiinher, and it is proposed to lengthen it to 75 years, with 

 I') compartments. 



Trivatc forests of maritime pine near Arcachon arc chiefly 

 managed for the yield of resin, and are consequently tapped younger 

 and more severely than the State forests. 



Boppe estimates that in a private maritime pine forest 45 yeai-s 

 old eacli tree will yield 6i to 10 pounds of crude resin per annum. 

 Tlie yield per acre varies greatly, according to the nature of the soil 

 and the management ; 200 to 450 pounds per acre per annum are 

 given as the extremes. The value of the cask of resin containing 

 235 kilograms (G25 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 hai'ras is added by the workman to the 

 extent of 50 kilogi-ams 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.* 



Section III. — Tapping Other Species for Eesin. 



1. Silver-Fir. 



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

 bark, where a few drops of resin accumulate in little projecting 

 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 gradually abandoned, produces Strasburg 

 resin. 



2. Sj^ruceA 



Tlie spruce is tapped for resin by cutting long narrow grooves 

 (:J to G centimeters broad and 1 to 1"5 meter long) through the 

 bark of the trees down to the cambium-zone. As a rule, two 

 grooves are thus cut on opposite sides of a tree, and when the 

 supply of resin from them fulls oft", two more are opened between 



•^j\ii account of the iinwhicts prcparfd lioiu crude resiu is given in Part iii., 

 J). 77<> of tlie inesent book. 



t t'fhia account is taken from Gayer.— Tii.] 



