The earth of Sumatra is rich in minerals and other fossil productions.

Gold.

No country has been more famous in all ages for gold, and, though the sources from whence it is drawn may be supposed in some measure exhausted by the avarice and industry of ages, yet at this day the quantity procured is very considerable, and doubtless might be much increased were the simple labour of the gatherer assisted by a knowledge of the arts of mineralogy.

Copper, iron, tin, sulphur.

There are also mines of copper, iron, and tin.  Sulphur is gathered in large quantities about the numerous volcanoes.

Saltpetre.

Saltpetre the natives procure by a process of their own from the earth which is found impregnated with it; chiefly in extensive caves that have been, from the beginning of time, the haunt of a certain species of birds, of whose dung the soil is formed.

Coal.

Coal, mostly washed down by the floods, is collected in several parts, particularly at Kataun, Ayer-rammi, and Bencoolen.  It is light and not esteemed very good; but I am informed that this is the case with all coal found near the surface of the earth, and, as the veins are observed to run in an inclined direction until the pits have some depth, the fossil must be of an indifferent quality.  The little island of Pisang, near the foot of Mount Pugong, was supposed to be chiefly a bed of rock crystal, but upon examination of specimens taken from thence they proved to be calcareous spar.

Hot springs.

Mineral and hot springs have been discovered in many districts.  In taste the waters mostly resemble those of Harrowgate, being nauseous to the palate.

Earth oil.

The oleum terrae, or earth oil, used chiefly as a preservative against the destructive ravages of the white-ants, is collected at Ipu and elsewhere.*

(Footnote.  The fountain of Naphtha or liquid balsam found at Pedir, so much celebrated by the Portuguese writers, is doubtless this oleum terrae, or meniak tanah, as it is called by the Malays.)

Soft rock.

There is scarcely any species of hard rock to be met with in the low parts of the island near the seashore.  Besides the ledges of coral, which are covered by the tide, that which generally prevails is the napal, as it is called by the inhabitants, forming the basis of the red cliffs, and not infrequently the beds of the rivers.  Though this napal has the appearance of rock it possesses in fact so little solidity that it is difficult to pronounce whether it be a soft stone or only an indurated clay.  The surface of it becomes smooth and glossy by a slight attrition, and to the touch resembles soap, which is its most striking characteristic; but it is not soluble in water and makes no effervescence with acids.  Its colour is either grey, brown, or red, according