mineralogical description of the island of banka. 401 
When struck with an hammer it separates at the fissures, which 
appear on the surface, into irregular fragments; it also frequently 
follows the direction of the streaks or lines : these are formed of a 
substance hard and semi-transparent, approaching the nature of rock- 
crystal. They often separate from the common mass of the stone 
into extensive laminae of unequal thickness from half a line to a 
quarter of an inch: In many cases, however, they are closely united 
to the substance of the rock, they appear on the fracture but cannot 
be separated. This rock is completely siliceous, and exhibits not 
the least sensibility on the application of the strong acids. 
The village of Kdmpdk is situated about half a mile from the dis¬ 
charge of this river ; the banks are here elevated about 12 or 15 feet 
above its common level at low water. After some search I discover¬ 
ed a spot where they were exposed by an artificial section ; they 
here consisted of a stratum of the red-iron-stone formed of fragments 
of various figures, from the size of a pea to that of several inches m 
length and diameter, disposed in very fine sand adhering partially by 
means of particles of clay; they were all rounded at their edges and 
bore the marks of having been carried down by the stream. Alter¬ 
nating with this stratum, and in some instances immediately under 
the soil, I remarked extensive masses of clay of a reddish ground, 
variegated with yellow and white ; small fragments of red-stone were 
often bedded in it. 
From Kampfik the direction of the river is winding through the 
alluvial plain to its third branch which leads to the stockade of Je¬ 
hus ; the profuseness of vegetation along the whole course, extending 
completely to the water edge, prevents an accurate examination of 
the banks ; in several places where they were exposed they exhibi¬ 
ted a black vegetable mould. The stockade of Jebus is built on the 
first elevation beyond the level of the river: I examined the frag¬ 
ments of stone which were thrown out in making the ditch which 
surrounds it; they are of the same kind as those found near the river 
at the village of Kampak, small Red-Iron-stones all bearing the marks 
of attrition, corroded on the surface, flat, oblong reniform, variously 
excavated, perforated and rounded, the fracture exhibited a red or 
