VARIETY OP SULPHATE OF LIME. 
into notice by Mr. Sowerby, who has given of it a description Analysis of a 
and drawing, in his British Mineralogy. 
I^alural History of the Fossil. 
It occurs massive, accompanied by granit, in the hill called 
Tyre-Beggar, near Dyce, in Aberdeenshire. The colour of 
this fossil is a pale greenisli white. It becomes phosphorescent, 
and shines with a greenish light when heated to a dull redness, 
for a few minutes only . A more intense and longer continued 
heat, destroys its capability of shining in the dark- On expo- 
sure to moist air, it slowly disintegrates and becomes covered 
with a white dusty efflorescence. Its recent fracture exhibits 
a silky lustre, and appears to be composed of bundles of very 
mmute needle-shaped crystals, scarcely distinguishable by the 
naked eye. It is very hard, but may be scratched with a steel 
point. It is copiously interspersed with dodecahedral garnets of 
the size of large pease. Its specific gravity is 2‘95. 
Analysis. 
In order to examine the agency of acids on this mineral, I 
introduced detached portions of it, finely pulverised into four 
separate flasks, and poured upon one, sulphuric acid, upon the 
other, nitric acid, and upon the third, muriatic acid mode- 
rately diluted, and subjected them for some hours to a gentle 
heat. t 
From this experiment I learnt that the nitric and sulphuric 
acids had produced no change, because the mineral w-as again 
obtained from the acids unaltered in weight, and qualities, by 
mere ablution with water. The muriatic acid alone produced 
with the fossil, by long-continued digestion, a gelatinous 
fluid. 150 grains of it, exposed to a red heat, lost 3 grains. 
It did not fuse. 
I..earning from these preliminar)’ steps, that the analysis could 
not be effected by the agencies of acids, I heated the mineral 
with charcoal powder to redness. This mass, when moistened 
with water, evolved a strong odour of sulphuretted hydrogen, 
a proof that sulphuric acid was present in the fossil. 
A. 150 
