:286 Annual Rej)ort of the Consulting Chemist. 



Silica 43*50 



Alumina and a little oxide of iron 22'95 



Lime 31-50 



Magnesia and loss in analysis 2 • 05 



100-00 



In a chemical point of view iron-slag is a double silicate of 

 lime and alumina, with a little silicate of magnesia derived frorn 

 the limestone employed in the iron-furnaces. 



By a new and very cheap process iron-slag may be completely 

 disintegrated by being run red-hot into a rapidly revolving wheel 

 and violently agitated in water. This disintegrated material, 

 resembling in appearance pumice-stone. Lord Cathcart informs 

 me, can now be had in any quantity for little more than the cost 

 of carriage. 



The results of the preceding analysis show that lime and silica 

 are the two constituents of slag which are capable of rendering 

 good service to vegetation. The proportion of lime in iron-slag 

 is considerable, and there cannot be much doubt about the utility 

 of the fine disintegrated slag for improving moor land or peaty 

 soils. 



It is true the lime is combined in the slag with silica, and 

 therefore it is not so readily available to plants as caustic lime. 

 On the other hand, the effects of the lime in iron-slag appear to 

 me likely to be more permanent than the effects of quicklime ; 

 and as the slag can be procured for little more than the cost of 

 carriage, it may be applied to all land in much larger quantities 

 than quicklime can be applied, for economical reasons ; and when 

 used in large quantities, say five or six tons per acre, I have no 

 hesitation in saying that sufficient lime will be liberated from the 

 silicate of lime of the slag to meet all the requirements of the 

 crops usually grown on the farm. 



The artificial disintegration of the slag I believe greatly favours 

 its decomposition in the soil, and fits it to yield both lime and 

 silica to vegetation. Before it can be useful to the plant the slag 

 must undergo decomposition. The carbonic acid produced in 

 the soil by decaying vegetable matter gradually acts also upon the 

 silicate of lime, converting it into carbonate of lime on the one 

 hand, and liberating from it, on the other hand, silica in a gela- 

 tinous and readily soluble condition. In peaty soils and such as 

 are rich in vegetable matter, this decomposition will take place 

 with greater rapidity, and hence the greater fitness of iron-slag 

 as an application to such soils. 



Silica is necessary, especially to our corn and grass crops, and 

 therefore anything which will supply it to the peat in a soluble 

 form is supposed to possess much virtue as an application to the 



