PROCEEDINGS 1841 — 1848. 
183 
a black glassy slag. Thus the slate rocks appear to be decidedly less 
fusible, less easily acted upon by heat than the porphyries. The 
same result was obtained in fusing fragments of Skiddaw slate, 
Skiddaw gi'anite, and porph)rry, in a common reverberatory furnace. 
A white heat was required to fuse them, but the granite and porphyry 
melted much more readily than the clay slate when pressure was 
employed to consolidate the powders of granite, Skiddaw slate, and 
porphyry in strong tubes, and the compressed mass was secured by 
screwing down. The melting occurred in each case at a lower heat 
wdth pressure than without. A red heat was sufficient to fuse them, 
when slowly cooled they resumed a stony texture and did not resemble 
the glassy slags produced by fusion without pressure. A large mass 
of syenite of Charnwood Forest was melted in the reverberatory 
furnace and slowly cooled. It showed every gradation of texture 
from that of glassy slag to stony, granular, and even porphyritic 
structure. By exposing glassy slag to heat below fusion for two or 
three weeks, a stony texture is found to be induced. It is much to 
be wished that experiments of this kind may be repeated under 
pressure, and, if practical, in presence of moisture, for in every view 
of the Plutonic rocks moisture must be conceived to have been 
present. According to the theory of a cooling globe, the influence 
of the atmosphere and ocean must have been very strongly felt in the 
formation of compounds by consolidation from fusion, while, according 
to the theory of volcanic heat being generated fi'om the contact of 
water and unoxidised bases of alkahes, earths, and metals, some 
trace of water should appear, as, in fact, it does in the minerals 
crystalised in lava." 
No report was presented in 1845, but at a meeting of the 
Council held at the Philosophical Hall in Leeds, on Monday, February 
3rd, it was resolved that the services of a paid secretary are essential 
to the prosperity of the society, and that as the present funds are 
inadequate to the payment of a liberal salary to a competent person, - 
the following gentlemen be appointed a committee to consider the 
propriety of proposing such a reduction in the amount of subscrip- 
tion as may induce a large increase in the number of members, and 
that the committee be instructed to communicate with the president 
