15 



Fourth period. Six years after the expiration of the third period the 

 harvest of cork may be taken from the surface measuring 48 inches on 

 the upper portion. At the end of the period of development the harvest 

 will be produced as before from the surface measuring - 48 inches on the 

 lower portion of the tree, which at this time will measure 34 to 39 inches 

 in circumference. A surface of 24 inches in length situated above the 

 last barked surface should now be prepared for a future harvest. 



Fifth period. Six years after, the harvest will be taken from the 

 surface having a dimension of 48 inches situated in the central part 

 of the trunk. At the expiration of the period of development the cork 

 can be taken from the 48 inches of surface on the lower part of the 

 tree and the 24 inches situated on the upper part of the trunk. The 

 measurements of various portions of the trunk will vary from 39 to 48 

 inches in circumference. 



At the end of the fifth period the barking of the wild bark is not 

 extended further unless the vigor of the tree well permits an increase 

 of the barked area, and thereafter only the commercial cork is gathered 

 twice during each period, alternating the harvest from the surface hav- 

 ing a measurement of 48 inches situated in the center of the trunk with 

 that of the surfaces having a measurement of 48 inches situated at the 

 base and top of the trunk. 



PREPARATION FOR MARKET. 



The cork, having been stripped from the trees in the form of slabs or 

 cylinders, is first placed in long rectangular vessels and boiled for the 

 purpose of swelling the bark. The boiling closes the pores, increases 

 its elasticity, and renders it more supple and compact. The efficacy of 

 this treatment is incontestable; its specific weight is reduced, but the 

 volume is increased about 20 per cent. 



The vessels used are about 6 feet square and will hold from 3 to 5 

 hundredweight of bark, which is flattened and held in position by means 

 of heavily weighted planks. The cork is boiled about one-half to 

 three-quarters of an hour. After boiling, the cork slabs are allowed to 

 cool. They are then scraped with an instrument, either by hand or 

 machinery, by which means all the wood fiber is removed. The loss in 

 weight is greater when treated by machinery than by hand. After 

 the operation of scraping, the cork slabs go to the cutter, who trims 

 them in proper shape, removes the defective parts, and sorts them 

 into grades suitable for different purposes. The various qualities are 

 placed in five classes, namely, thick, ordinary, bastard or fair, thin, and 

 refuse, having measurements as follows : 



1. 'i'liick, measuring 31 millimeters or above. 



2. Ordinary, measuring 26 to 30 millimeters. 



3. Bastard or fair, 23 to 25 millimeters. 



4. Thin, 22 millimeters. 





