163 
MlCEtLAtfEOtJg NOTICES &(•.. 
passage of the lignite into the carbonaceous silex can be dis tine tty 
traced. The lignite first becomes harder, with a somewhat dull as¬ 
pect; minute granules of silex then appear, and continue to in¬ 
crease in number until they break up the base as it were, and 
gradually occupy the whole of it and form the saccharoid rock. 
Under the microscope, with a power of 450, the dull hue is 
seen to be caused by very minute crystals of quartz, each of 
which is isolated and closely invested by the jet* The com¬ 
mon siliceous rock is also seen to consist of microscopic siliceous 
crystals of watery and yellowish hues, with more or less of car¬ 
bon disseminated amongst them, the blackish hue which some 
specimens have, and the blending of both colours into one uni¬ 
form hue in others, arising from the lighter colored crystals be¬ 
ing imperceptible to the eye. 
In a few specimens we see alternate layers of lignite,—com¬ 
pact or very finely granular, black, lapidified, layers,—layers re¬ 
sembling greyish carbonaceous sandstone,—and layers having com¬ 
pletely the aspect of brownish and brownish black decayed crum¬ 
bling wood save that while some parts have the proper dull hue 
the rest has a glistering lustre. The two latter when examined 
by the naked eye appear as if sedimentary sand had been depo¬ 
sited between layers of vegetable matter, in the one case; and in 
the other, had penetrated into the interstices of the decayed wood, 
the microscope how'ever shews the minute glistering granules to be 
regular six sided prisms with pyramidal extremities and so iso¬ 
lated, in many instances, as to leave no doubt that they have crys¬ 
tallised in situ. 
The specific gravity of the most siliceous rock is 2, 58. On 
' This is a very fine instance of that process by which new minerals are 
introduced into the heart of other minerals without any apparent channel. 
Tn many cases where most ot the elements of the new mineral exist in the 
matrix the process may have been merely a chemical one, but in others, 
where new elements are found, electricity has probably been the instru¬ 
ment of the change. In the present case the silex is imbedded in a lignite 
having a \ ery minute proportion of ash, and although the siliciotis matter 
may have been introduced in a gaseous or liquid state and then crystalisad, 
an equal bulk of the carbonaceous base appears to have been re moved for 
each crystal of silex that was formed. Unless we admit the doctrine of 
isomeric transmutation of elements, which (notwithstanding Dr.S. Brown’s 
expei imcnts which he supposed to prove the conversion of carbon into sili¬ 
con, &c.J is generally rejected by cbemists, we must believe that electrical- 
agency replaced the carbon by silex. 
x 
