170 VEGETABLE SUBSTANCES. 



CHAPTER X. 



CORK-WOOD TEAZLES ULVA MARINA. 



CORK is the bark of an evergreen oak, which has been 

 already described in our account of timber trees. 

 It grows in the southern parts of Europe and on 

 the shores of the Mediterranean. This tree is to be 

 seen in our English gardens, but bearing evident 

 marks of its exotic growth. 



Cork-trees are generally fifteen years old before 

 they arrive at sufficient maturity to yield a supply of 

 bark, and after this, at intervals of eight years, the bark 

 is always sufficiently renewed to be again removed. 



The cork is stripped off in large masses, from two 

 to three inches in thickness, and retains the curved 

 figure corresponding with that of the trunk of the 

 tree. The only preparation required is to reduce it 

 to a plain compact surface. In order, chiefly, to 

 impart closeness of texture, it is scorched on both 

 sides, and while still hot it is laid between flat heavy 

 planks where it remains until cold. 



The elasticity and the levity of cork cause it to 

 be extremely useful wherever those properties are 

 desirable. Since it can be readily compressed, and 

 will expand again as soon as the compressing power 

 is removed, it fills up very closely that space into 

 which it had been driven by force; while its numerous 

 pores are so minute that neither water nor any com- 

 mon liquid can escape through them, and even the 

 more subtile particles of alcohol but very gradually, 

 and that after a considerable space of time, penetrate 

 through this almost impervious substance. A more 

 compact wood, but having wider pores, affords a 

 passage with greater facility to fluids. Cork is more 



