and Volcanic Substances. 221 
rous, porphyritic or amygdaloidal. This is accompanied 
by stones fused, half fused, ignited, heated, or warmed, 
acted on by fire so as to affect their appearance, or not so, 
according to the degree and continuance of the heat, and 
_ the nature of the stones thus acted on. This statement re- 
quires no proof to persons accustomed to look at volcanic 
regions, or even cabinet specimens of well selected volca- 
nic productions. _ 
__ sill these characters, belong to the Basalt of France and 
‘Germany, and to the whin and toad stone of Great-Britain. 
They belong to no other class ofrocks. Every known 
character that Lava possesses, is possessed also in like man- 
ner, and under like circumstances, by the newest fletz trap 
of Werner. Werner himself was aware of it, for when on a 
visit to Paris.a few years before his death, he was invited, 
and urged to pay a visit to Auvergne, he steadily declined it. 
- He had already put the detached masses of Saxon Basalt 
into his Neptunian formations, finding them to repose upon, 
and to alternate with rocks decidedly of Neptunian origin. 
He called them, rocks of the newest fleetz trap formation. 
Newest because they were found covering the alluvial, 
and the most recent of his secondary formations. 
_ Fletz, because, covering the fleetz or horizontal rocks, 
they appeared to belong to that series. 
Trap, from the hornblende character so observable in 
Basalt. He does not seem to have distinguished between 
Augit and Hornblende, as being decisive of the character of 
igneous rocks. 
The rocks usually ranked as fletz trap, by the Werne- 
rians, are Basalt, Porphyry, Amygdaloid, Greenstone, 
Pitchstone, Obsidian and Pumice. It is hardly necessary 
at the present day, to prove that the three last of these rocks 
are igneous in their origin. I shall take it as conceded that 
they are so. 
J proceed then to shew, 
1. That the columnar, prismatic, figurate basalt, so com- 
mon among these disputed rocks, is common also among 
the best known active volcanoes, which abound in basalt of 
all kinds. 
2. That Basalt leaves decided aba les of fire on the sub- 
stances contiguous to it. 
Vor, IV....,.No: 2. 3 
