42 



Economical Geology. 



stones. In Great Britain, basalt has been, within a few years, used 

 for this purpose, and found even superior to the French buhrstone ; 

 and our greenstone is only a variety of the same rock ; indeed, some 

 of our greenstone cannot be distinguished, by the eye, from the Eu- 

 ropean basalt. It is generally extremely compact and tough ; and 

 although its preparation might require a little more labor than the 

 buhrstone, yet it would doubtless last enough longer amply to pay for 

 the additional labor. In the vicinity of Boston and in the Connecti- 

 cut valley, as may be seen on the Map, greenstone exists in great 

 quantities. It also occurs in small beds throughout the whole extent 

 of the gneiss region ; and of a kind, which I should suppose from its 

 appearance, would answer the purpose even better than that of the 

 extensive ranges above mentioned. 



Coal. 



Of this mineral, the object of so much interest in every civilized 

 country, there are found three distinct species ; all of which are some- 

 times employed as fuel. The most common in Europe, which is 

 there considered the best, is the bituminous coal, or that containing bi- 

 tumen. This burns readily with a yellow or white flame. A second 

 species is the anthracite, or stone coal ; which is generally described 

 as burning without flame, because destitute of bitumen. The anthra- 

 cites of this country, however, burn with the flame that results from 

 the combustion of hydrogen ; this gas existing in a state of combina- 

 tion, either with the carbon, or in the water which the anthracite con- 

 tains ; and it is liberated by the heat. The great difficulty in the use 

 of anthracite, consists in igniting it: a difficulty which has almost 

 disappeared before the ingenuity of our countrymen. In Europe, 

 Anthracite has been described as of little value: with the exception, 

 perhaps, of Killkenny coal. But our Anthracite is either of a qual- 

 ity superior to the European, or we have learned better methods of 

 employing it. All the coal obtained from the inexhaustible beds of 

 that mineral along the Susquehannah, Lehigh, and Schuylkill, in 

 Pennsylvania, is anthracite ; and wherever it is skillfully used, I be- 

 lieve it is decidedly preferred to the best bituminous coals of England, 

 or the United States. The coal from Rhode Island, (chiefly from 

 Portsmouth at the north end of the Island, is also anthracite. The 

 Worcester coal belongs to the same species : indeed, every enlighten- 

 ed man in this country now regards our anthracite as a great national 

 blessing. But in Great Britain, their geological writers speak of the 



