1817.) Geological Society. 473 
Hon. Mem. G. S. entitled, ‘« Description of the newly-discovered 
Heads of Encrinites, of which 17 Drawings are sent for Exhibition, 
and a Sketch of the District wherein they are found, was read. 
A stratum of encrinital lime-stone from 20 to 40 feet thick is 
seen cropping out ina line from the Black Rock, near Bristol, to 
the shore of Clevedon Bay, and at the back of a tongue of land 
called Woodspring Point. Throughout this rock remains of stems 
of encrinite are abundant, together with other marine exuvie ; but 
till lately no remains of heads were found. After long research, 
however, by Mr. Cumberland, and other gentlemen of the neigh- 
bourhood, some of these parts of the animal were discovered, and 
investigation proves they are of several species. Among them, as 
appears by the drawings, is the nave encrinus of Parkinson; but the 
greater number are of species hitherto unknown. 
A paper by Arthur Aikin, Esq. M.G.S. was read, entitled, Some 
Observations on a Series of Specimens from Torre del Greco pre- 
sented to the Geological Society by the Hon. H. G. Bennet. 
On June 15, 1794, part of the town of Torre del Greco was 
overwhelmed and buried by a stream of lava from Mount Vesuvius. 
About twelve months afterwards the lava had considerably cooled, 
the heat indicated by a thermometer placed in the crevices being 
178° Fahrenheit, and new buildings were erecting on it. In 
digging the foundations of these new houses, the ruins of those that 
had been covered by the lava were occasionally broken into, and 
several articles were obtained which had during a year been sub- 
jected to the heat of the torrent. Many interesting specimens of 
these were obtained by the Hon. H. G. Bennet, who has presented 
them to the Geological Society ; and Mr. Aikin, in this paper, has 
given his observations upon them. 
Several pieces of glass, which appear to have been acted on in 
various degrees by the heat, show changes similar to those produced 
in the laboratory by burying them in red-hot sand, excepting that 
this slower process has produced the more crystalline structure. 
Those which have actually undergone fusion have become masses 
more or less cellular, differing but little in structure and general 
appearance from ordinary glass. ‘These changes coincide with the 
results obtained by Reaumur in his experiments. 
Pieces of iron have become converted into the state of black, red, 
grey, and magnetic oxide, and having in the hollows and inter- 
stices crystals of brownish-red transparent oxide of iron, and of 
specular iron ore. From the changes that the various articles of iron 
have undergone, the author concludes that there was little, if any, 
free sulphur in the lava, since there is no appearance of iron pyrites. 
Also, as the forms of the articles have not been materially altered, 
and the crystals are in many instances produced by sublimation, that 
iron or its oxide becomes volatile at a much lower temperature than 
has hitherto been observed. 
Pieces of copper show changes into the states of crystallized red 
oxide, and red oxide mixed with green and blue carbonate. 
