226 



COMPOSITION OF LIMESTONES. 



of these different varieties of lime be applied, which is a mode- 

 rate dose, the one gives to the land the phosphate of about ten 

 bushels, the other of about a bushel and a half, of bones. It is 

 obvious, therefore, not only that the fertilising action of the 

 lime which contains the larger quantity must be modified in a 

 considerable degree by the presence of the phosphate, but that 

 the sensible effects of the two different limes must differ with the 

 quantities of this compound which they respectively contain. 



The following tables exhibit the composition of four varieties 

 from the carboniferous limestones of Cumberland, Dumfries, 

 and Lanark, respectively, in their natural or unburned, and in 

 their burned states. They were analysed in the burned state, 

 as they are represented in the second table ; I have been unable, 

 therefore, to distinguish between the gypsuin existing naturally 

 in the limestone and that which was formed during the burning 

 in the kiln. 



a Composition of the limestones : 



Carbonate of lime, 

 Sulphate of lime, . 

 Phosphate of lime, . 

 Carbonate of magnesia, 

 Alumina and oxides of iron, 

 Silica, . 



100 



100 



I Composition of the burned limes : 



Cockermouth, Brampton, 

 Cumberland. 



100 



Kilnhead, 

 Dumfries. 



100 



Carluke, 

 Lanark. 



Lime, .... 



Sulphate of lime, . 



Phosphate of lime, . 



Magnesia, 



Alumina and oxides of iron, 



Silica, in the state of silicate, 



Carbonic acid and moisture, 



100 



100 



100 



100 



The limes, of which the latter table represents the compo- 

 sition, differ not only in the proportion of caustic lime they 

 respectively contain, but also in that of gypsum and of phosphate 





