^58 Di’ Traill on the Mincmhgy of Halkm Mountain, 
other side of Halkin. I am disposed to consider it of a distinct 
series of bedsi The clay-pit presents a remarkable appearance. 
It occupies a basin apparently in the limestone. Just below the 
soilj lies a coarse clay, coloured by iron, and in some places by 
carbonaceous matter. It is friable, from being much mixed 
with sand, The colouring matters are unequally distributed, 
giving a variety of red and yellow tints. The carbonaceous 
portions are blackish^grey, but they burn white in the fire. 
They have been used as an oil-paint. Under this lies a thick 
bed of very white quartzy sand, slightly cohering while wet, 
from containing a little white clay. This sand, when washed, 
seems well adapted for the glass-house, or might be used instead 
of flint-powder in porcelain manufactories. In some places, this 
sand is richly variegated with bright red and yellow hues, from 
nests of coloured clay, the yellow portions of which have most 
of the qualities of variegated clay. The bed of sand becomes 
more fine as it descends, and, at the depth of two or three yards, 
passes into a pure white clay, which we shall now describe. 
The great mass of this clay, when dried, has the following 
characters. It is either snow-white, or has the faintest tinge of 
greyish-white. Its particles are dull and dusty, soiling strongly. 
When rubbed between the fingers, the fineness of its particles 
prevents harshness, and it is rather soft, though not greasy to 
the touch. This is the general character ; but some masses 
disseminated through the bed, and especially in the lowest point 
yet reached, have rather a greasy feel, and, when rubbed, be- 
come shining on the surface, as if passing into lithomarge of the 
purest white colour. The clay adheres a little to the tongue. 
Its specific gravity is S.4885. 
When either the dull or the greasy-looking clay is thrown in- 
to cold water, it rapidly gives out air, with a hissing sound, and 
falls into powder ; the greasy sort rather less rapidly than the 
other: but both are inclined to form a paste with v>^ater. In 
some experiments which I made, specimens of the clay yielded 
more than 80 per cent, of silica ; the rest was alumina, and a most 
minute trace of iron ; but as I afterwards discovered that the 
subject of my experiments had been diffused through water, 
and again dried, after it was taken from the pit, it is my inten- 
