WESTERN DISTRICT. 273 



Water of absorption 0*56 



Organic matter 5*00 



Silex 34-56 



Carbonate of lime 43*06 



Alumina and protoxide of iron 13-36 



Sulphate of lime 1-06 



* Magnesia 2-17 



99-71 



The rod and green marly rock, when submitted to the action of cold water, furnishes 

 a quantity of soluble matter. Thus from 100 grains, we obtained of 



RED MARL. GREEN MARL. 



Soluble matter 1-25 3-50 



Organic matter or aeids. 0-57 0-87 



Saline or bases 0-68 2-63 



The thin beds of green shale are subject to decomposition, and the debris remains on 

 the dry shelving rocks in the form of gray bitter powders, consisting mostly of the sul- 

 phates of soda and magnesia, mixed also in varying proportions with the chlorides of 

 sodium, magnesium and calcium, and the sulphate of lime and sometimes alumina. One 

 hundred grains of the most earthy powder yielded of 



Soluble matter 6-53 



Organic matter 1-03 



Saline matter 5-50 



The latter consists of the above enumerated elements. In many instances the saline matter 

 may be collected in a pure condition, or nearly free from earthy matter. This fact explains 

 the cause of the constant fertility of the soils derived from these rocks : the amount of 

 saline matter which they furnish is always sufficient to supply the wants of vegetation. 

 The analysis of the shales gave another important fact, namely, that the organic salts 

 exist in them ready formed. 



Vegetable materials may be recognized always when they are ignited, both by their 

 blackening, and by the peaty odor which they exhale when subjected to the action of 

 heat. This organic matter must have been derived from vegetables which belonged to the 

 period when the rocks were being deposited. It also increases the fertility of the soil ; and 

 as it is furnished in proportion to the disintegration of the rock, it can rarely happen that 

 the soil will be exhausted of its organic matter by a judicious course of husbandry. 



The condition of the organic matter is much the same as that which exists in ready 

 formed soils : crenic and apocrenic acids constitute the greater part of it. These are 

 combined with the alkalies and alkaline earths, which, when they have been ignited, are 

 decomposed, and pass to the condition of carbonates. Hence it is that we obtain carbonates 

 in all our analyses, where rocks or soils have been subjected to a red heat. The carbonates 

 [Agricultural Report.] 35 



