636 LIGNITE. 



organized kinds, approaching very near to peat, 

 while the more compact, such as jet, approxi- 

 mate to coal. 



Chemical analysis proves that the most im- 

 perfect peat differs little from wood, and that jet, 

 the most perfect lignite, differs in the same man- 

 ner but slightly from coal. The intermediate 

 varieties between these extremes, present cor- 

 responding differences which show that the whole 

 of these substances are in the progress of bitu- 

 minization, and which render it probable that, 

 by the completion of that process, and by certain 

 changes in their texture, they are ultimately 

 destined to form that substance. It is not within 

 the limits of this work to enter further into this 

 interesting subject, which will find a more ap- 

 propriate place in a system of geological science. 



Lignite is found in strata varying in thick- 

 ness, from a few inches even to fifty feet, and, 

 sometimes occupying extensive tracts in alluvial 

 valleys. It is always covered with the alluvial 

 deposits, and, although it sometimes forms only 

 one stratum, it occasionally exists in repeated 

 alternations with clay, sand, and marie, and 



