356 — Notice of Professor Steffens” Geological Writings. 
great many natural phenomena, by the idea of their being 
placed in a necessary contrast to others, a contrast with which 
the phenomena of polarity, observed in so many natural ob- 
jects, might be compared. Steffens was the first, nay, the 
only one, who attempted, and that in a most able manner, to 
apply to geology this mode of investigation, to which we are 
indebted for numerous additions to our knowledge of the na- 
tural sciences. At that period he wrote a work, which was 
received with the most lively interest by his contemporaries, 
and was entitled, Contributions to the Natural History of the 
Interior of the Earth (Beitrage zur innern Naturgeschichte der 
Erde, Freiberg, 1801). This book contains many attractive 
delineations, is filled with a rich collection of geological views, 
and is altogether most remarkable for the time at which it 
was written. He regarded the alkalies and earths as metallic 
oxides (as had previously been supposed by Lavoisier and 
Bergmann); and his account is peculiarly animated of the 
great contrast, which he himself first pointed out, between the 
siliceous and calcareous series of the newer formations of the 
crust of the globe, by means of which all rocks of the Neptu- 
nian origin can be arranged under two principal groups. He 
directed attention to the remarkable fact, that, of the higher 
extinct organisms, stratified rocks belonging to the siliceous 
series contain chiefly remains of plants, the largest accumula- 
tions of which present themselves in the rocks of the coal for- 
mation, and hence he concluded that the development of such 
organisms was necessary for the formation of the coal itself. 
In the rocks of the calcareous series, on the other hand, there 
is the same predominance of animal remains ; it is there that 
the coral rocks and beds of shells are found, which seem 
to require for their formation the existence of a consider- 
able quantity of lime in the surrounding medium. Beds of 
coal in limestone rocks were at that time quite unknown, and 
are even’yet arare and inconsiderable phenomenon. Steffens 
therefore concluded that the origin and further development 
of nitrogen was connected with the appearance of lime, and 
hence considered that the great contrast which was expressed 
in the higher organisms, by the simultaneous advancing de- 
velopment of the animal and vegetable kingdoms, had been 
