190 Prof. Nepomuk Fuchs"* Chemical Views regarding 



3. Carbonaceous series. — This series, although the smallest, 

 is of great importance. It commences with graphite in the 

 primitive rocks ; and the black limestone and clay-slate, more 

 especially drawing slate and alum-s\ate, and the substance termed 

 lydian stone, attest its presence and its advancing progress. 

 These substances form the continuation of the carbonaceous 

 series in the transition class, where also anthracite makes its ap- 

 pearance in considerable masses. But this series acquires its 

 greatest development in the older rocks of the secondary class, 

 in the true coals ; and it ends with the varieties of brown coal 

 in the newest formations, if we do not regard peat as its last 

 member. To this series also belong the different kinds of 

 mineral pitch which occur in limestone, sandstone, marl, and 

 clay. 



It is only graphite, anthracite, and diamond that are almost 

 universally regarded as original mineral products, and doubts 

 have even been entertained on the origin of these substances. 

 All the others are considered as strangers derived from the ve- 

 getable kingdom. There are many circumstances in favour of 

 this opinion, such as the chemical constitution of these bodies 

 which is similar to that of plants ; the not unfrequent occurrence 

 of vegetable remains, even of entire stems of trees along with 

 coal ; and finally, the distinct passage of wood into brown coal, 

 which, externally, often bears the greatest resemblance to black 

 coal. 



But here we also meet with great difficulties. Thus, we 

 cannot comprehend how it happens that strata of coal so often 

 alternate with other strata, as of sandstone, slate-clay, &c. ; for 

 we can hardly suppose that each bed indicates a new vegetation. 

 Further, we cannot understand how the vegetable fibres have 

 been so completely altered, that they have not only lost their 

 form and all signs of organization, but have even been con- 

 verted into a half-liquid mass, for such a condition must have 

 preceded the formation of coal, inasmuch as the carbonaceous 

 matter could not otherwise have penetrated into the clefts and 

 veinJike fissures in which we sometimes, find it. These diffi- 

 culties have not been overlooked by geologists, and recourse 

 has been had to sulphuric acid, in order to obviate the last. 

 But, besides that this acid, although it can produce a semi- 



