74 The Limestones, and Lime. [Feb., 



Silica, 21.0 



98.6 



Per cent of lime, 42.32. 



Limestone of Franconia. 



Carbonate of lime, - - - 78.00 

 Silex and mica, - - - 20.00 



Carbonate of iron, _ - . 2.00 



100. 



It contains 43.9 per cent of caustic lime. It is used as a flux 

 for smelting the iron ores of Franconia, and it is probably well 

 adapted for this use. The silex it contains becomes, as far as it 

 goes, an important addition to it for fluxing. It is also employed 

 in agriculture. 



It appears from the foregoing analysis, that magnesia is rarely 

 if ever present in these limestones. They are associated with the 

 mica slate and hornblende rocks. It is not usual to discover any 

 traces of stratification in them. Magnesia, which is more com- 

 monly present in limestone than is suspected, seems to be a rare 

 element here. 



4. P7'imary limestone of Maine. — Limestone of Androscoggin, 

 at Rumford Falls. Color white or gray, granular, containing ac- 

 tynolite, and pagasite. It is included between layers of slate, and 

 is much disturbed and contorted by a vein of granite. 



Analysis. 



Carbonate of lime, _ _ - 78.0 



Oxide of iron, - - - - 1.2 



Insoluble matter, _ _ _ 20.8 



100. 



This, Dr. Jackson remarks, burns fine in part, slackes quickly 

 and makes a strong white mortar of a good quality. Phosphate 

 of lime, pyroxine and hornblende are also found in this rock, 

 and it is principally from their presence that I infer that the 

 limestone whose analysis is given above belongs to the primary 

 system. 



The limestones of Maine, which are generally known as those 

 of Thomaston belong to the Taconic system. Others belong to 

 the new red sandstone. 



We have been particular in noticing the limestone beds of the 

 primary for the purpose of calling the attention of those who may 

 be interested in the subject to the fact, that those rocks are by no 

 means deficient in this important member, and may be sought for 



