130 
position, and forming these beautiful appearances. Being 
from Dalton in Lancashire, where it certainly could not 
have been expected, makes this specimen still more curious; 
for this substance was thought rare even in Scotland, and 
has but lately been discovered any where, as will be seen 
in the next table. 
The specimens I possess pass from transparent or opaque 
white to reddish or topaz-like yellow. They are con- 
tained in hollow stone cases, lined as it were by Analcime. 
—See tab. 59, and the lower left hand magnified figure of 
this plate. The crystals of Mesotype, which are peculiarly 
neat right-angled four-sided prisms terminated by obtuse 
four-sided pyramids, are sometimes a little varied as to 
the number of their angles: for when any faces of a regular 
crystal are, as it were, deeper cut, they borrow angles 
from their neighbours ; thus the otherwise regular three- 
angled plane of the four sided pyramid, trespassing occa- 
sionally on the column and opposite faces, becomes six- 
sided ; which will be easily understood by the figure. 
This substance differs from Stilbite and other substances 
which have been called Zeolites, not only in the form of 
the crystal, but in the fracture, and in being electric by 
heat. It is so far soluble in nitric acid as to form a jelly, 
which other similar minerals are not. Zeolites in general 
may be known by their being capable of a particular kind 
of ebullition, forming a frothy enamel under the action of 
the blowpipe. 
I figure some from Raghlin in Scotland, and have some 
specimens nearly similar, but not so fine, from Antrim, 
found among Basalt, and some from the county of Derry, 
by favour of my kind friends Dr. Scott, John Templeton, 
Esq., and Mr. Tennant. 
I suppose, now it is made known, it will be recognised in 
many places in Great Britain. It is, however, still to be 
remarked, that our authors are more generally backward to 
acknowledge British specimens than foreign ones. 
