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. Attheend 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 
ean 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 efticacy 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 t6 
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: 
. Thick, measuring 31 millimeters or above. 
. Ordinary, measuring 26 to 30 millimeters. 
. Bastard or fair, 23 to 25 millimeters. 
. Thin, 22 millimeters. 
Bm oO bo He 
