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periment, I hardly know any which I should prefer to this of Mr. 
Klaproth’s. According to the opinion offered, this substance should 
contain bitumen, into the composition of which carbon enters, in an 
abundant proportion — and, by the experiment, an effect is produced 
which excites the astonishment of this excellent chemist ; because it 
is that effect, which he would have expected from the presence of 
charcoal ; which he had no conception entered into the composition 
of the substance which was the subject of his experiment. Having 
obtained this satisfactory evidence, from the analysis of the semi-opal, 
the task remains to ascertain, whether any traces of the substance are 
to be discovered, in the opal itself. 
The OPAL, opal edler gelher- opal, Werner, the noble opal of 
some, and the oriental opal of the jewellers, in addition to the 
o-eneral characters which distinguish this class of fossils, possesses 
the astonishing property of displaying, in a strong light, the most 
vivid and beautiful colours, which continually play on the eye, with 
varying splendour, on the least change of position. From that 
spot which, the instant before, showed a beautifully bright green, 
or purple, a rose-coloured flame suddenly darts forth, forming what 
the amateurs of this stone term, the fire of the opal. But descrip- 
tion can furnish only a very imperfect idea of the brilliant display 
of colours yielded by this admirable and inestimable jewel. Our 
admired poet Thomson, indeed, appears to have succeeded, as far 
as the powers of language could enable him. It is in his address 
to the Sun, where he thus speaks of the wonderful properties of this 
highly elaborated work of nature. 
The unfruitful rock itself, impregn’d by thee, 
In dark retirement forms the lucid stone : 
The lively Dimnond drinks thy purest rays. 
Collected light, compact, that polish’d bright. 
And all its native lustre let abroad. 
Dares, as it sparkles on the fair one’s breast. 
