352 
THE GEOLOGIST. 
Tertiary age. Unfortunately tliey were lost during their transmission to' 
England ; tbut the author gave a list of genera and of some species since i 
obtained. 
Manchester Geological Society. — June ^Ofh. — Mr. Joseph Goodwin 
presented to the Society two specimens of shale ; one from the Jet Amber 
Mine, Haughton, containing minute shells of Anthracosia, and the other 
from the Peacock Mine, Hyde, containing beautiful specimens of ferns 
(Pecopteris), etc. A vote of thanks was passed to Mr. Goodwin for his 
donation. 
A collection of fossil fishes, consisting of Megalichthys, Helodus, etc., 
from the roof of the Spanish Juice or Half-yard Mine at Carr Knol, 
near Oldham, was presented by Mr. John Butterworth, of Moorside, 
Oldham. Mr. Wilde, of Moor Edge, sent for exhibition a fossil plant 
found in the sandstone at Oldham Edge, which he thinks proves that 
Halonia is but the root of Lepidodendron This connection of the two 
plants, Mr. J. S. Dawes, F.G.S., of Smethwick House, asserted he had 
proved many years since. 
The paper read was " On the Effect produced on Rowley Rag by Heat, 
and the practical Application of its Products to useful Purposes," by Mr. 
J. Plant. 
The author's object was to give an opportunity for the examination of a 
series of specimens which were obtained from Mr. Henry Adcock, the in- 
ventor and patentee of the Basaltic Stone Works at Oldbury, Worcester- 
shire ; these works, and nearly all similar works for the conversion of 
basalts and vitreous slags to ornamental purposes, having been discontinued, 
opportunities will consequently rarely occur for the examination of the in- 
teresting results of these experiments. 
The question as to the changes which heat has effected in the constitu- 
tion and cr3'^stallization of certain igneous rocks has ever been one of great 
interest to the geologist ; and with a view to explain certain theories upon 
the columnar structure and prismatic form of basalt, as observed generally, 
but more especially at the Giant's Causeway, Staffa, and the hill at Rowley 
Regis, experiments were conducted as early as the year 1801, by Mr. . 
Gregory Watt ; which experiments established the fact that basalt and trap 
were igneous rocks, and that the columnar structure of basalts could be 
experimentally produced under certain conditions of heat and pressure. 
Rowley Rag has been described by Senft as Melaphyre, an indistinctly 
mixed rock, intermediate between ordinary greenstone and black basalt, of 
dirty greenish-brown, hard and tough in a fresh state, having a specific 
gravity of 2*85, and a composition of silica, 55 ; alumina, 25 ; oxides of 
iron and manganese, 12 ; lime, 8 ; soda, 6 ; and inappreciable amounts of 
potash and magnesia. Mr. Watt fused 700 cwt. of this material, and kept 
it in a furnace several days after the fire was lowered. It fused into 
a dark-coloured mass, of a vitreous character, with less heat than was 
necessary to melt iron ; and a portion which was taken out whilst the mass 
was in fusion, and cooled quickly, became perfectly glassy. As refrigera- 
tion proceeded in the mass it became changed into a stony substance, and 
globules appeared ; these enlarged till they pressed laterally against each 
other, and became converted into polygonal prisms. The most important 
result observed was the formation of spheroids, sometimes extending to a 
diameter of two inches. They were radiated with distinct fibres, in some- 
what concentric layers ; but the centres of most of the spheroids became 
perfectly compact before they attained the diameter of half an inch. This 
structure gradually pervaded the whole body of the spheroid. A con- 
