GRAPHITE 209 



to contain lead, it was called black-lead or plumbago (Latin 

 plumbum, lead). 



The name graphite was given to it because it makes marks 

 on paper, from graphein, to write. 



It is found in very ancient rocks, such as gneiss, sometimes 

 in layers and sometimes in great lumps. 



Pencils are not now made of graphite alone, but of a mixture 

 of graphite and fine clay. Both substances are ground to a fine 

 powder, and then mixed with water to form a stiff paste. 

 This is put into a cylindrical vessel, perforated with holes 

 in the bottom, and forced through them. It emerges in the 

 form of long thin sticks. These are cut into convenient 

 lengths and allowed to dry. They are then made red hot, 

 after which they are ready to be inserted into the cedar- 

 wood holders prepared for them. 



Graphite is used as a dry lubricant for machinery, and for 

 this purpose alone we import large quantities every year ; it 

 is also used to polish fire-grates. 



As graphite is a very poor conductor of heat it is used 

 to line moulds into which white-hot metals are to be poured, 

 and (mixed with clay and sand) to make crucibles, in which to 

 melt ore and metals. These are its two most important uses. 



SOURCES OF SUPPLY. Borrowdale, in Cumberland, in former 

 days produced large quantities of graphite, but these mines 

 are now practically exhausted. 



Of countries within the empire Ceylon is the most important 

 contributor, though India, and to a smaller extent Canada, send 

 us supplies. Australia, and New Zealand, and the Transvaal 

 have deposits, but at present they are not much worked. 



The Ceylon mines are in the southern mountains, and the 

 ' output is much more than sufficient to render the empire 

 independent of foreign sources of supply '- 1 



As, however, she sends us only about one-fifth of her total 

 export, we have to buy more than half our supplies from foreign 

 countries. 



2203 



1 The Dominions Royal Commission. 

 O 



