62 



— or whether, as has been maintained, they are in fact of a decided- 

 ly more recent origin, are points only resolvable by cautious and 

 diligent investigation. 



In connexion with these sandstones and the rocks of the coal 

 measures, there occur in several places beds of earth sometimes 

 having nearly the firmness of a soft rock, containing a considera- 

 ble proportion of calcareous matter. In Prince Edward, where their 

 existence was first particularly remarked by Dr. Morton, these clays 

 and semi-rocks are occasionally so liberally impregnated with this 

 substance as to furnish a strong and valuable marl. At other points, 

 a mixture of carb. of lime and carb. of magnesia is found in beds 

 of considerable extent, and having a texture similar to the materials 

 above described. According to an analysis of a specimen of this 

 substance from Bear Island, it consists in 60 grains of 



Carb. of lime, 



31 



Carb. of magnesia, 



18 



Alumina, 



3 



Silica, 



7 



Loss, 



1 



60 



The occurrence in many parts of this region, of clays and rocks 

 thus abounding in calcareous matter, is certainly to be looked upon 

 as a happy circumstance. Those interested In availing themselves 

 of the fact, should have no difficulty In the application of these sub- 

 stances in the raw, or if necessary, in the calcined condition ; for, 

 even should they generally contain any notable proportion of 

 magnesia, the more enlightened experience of the present day would 

 seem to show that the presence of that earth is rather favourable 

 than injurious when associated with lime, and in some cases almost 

 equal in efficacy to calcareous matter itself. 



There is moreover another economical aspect in which this ma- 

 terial may be regarded. From the large proportion of magnesia it 

 contains, it would furnish an admirable resource for the manufacture 

 of that earth in the state of pure carbonate, or of what is at present 

 an object of much more extensive commerce, I mean the sulphate of 

 magnesia, or epsom salts. 



