THOMAS-SLAG OR BASIC CINDER. 



2.sr 



The chief peculiarities of this substance are that it contains 

 from an eighth to a fifth of its weight of oxides of iron, and 

 some metallic iron ; that the base lime is far in excess of the 

 acids, and when freshly made it is in the caustic state, so that 

 the reaction is strongly alkaline. There is an almost entire 

 absence of sulphuric acid, and the only thing in it that is soluble 

 in water is some of the lime, which, when put on the soil, will 

 have the effect of a gentle liming. One could scarcely anticipate 

 that a substance of that composition would be a successful 

 phosphatic manure, as he would probably be curious to know 

 the effect which the large amount of iron oxides might have 

 upon the crop. Now that that matter has been satisfactorily 

 proved, it is important to note the variation in composition to 

 which the substance is liable. The two analyses given above 

 show that the phosphoric acid may at least range from about 

 14 to about 20 per cent., equal to from about 30 to about 40 per 

 cent, of phosphate of lime, so that one sample of the slag may 

 have only three-fourths the value of another sample. 



During the short time the slag has been in existence, a large 

 immber of experiments have been made with it, chiefly on the 

 Continent. 



In 1885 Professors Wrightson and Munro made a somewhat 

 extensive series of experiments with it on the experimental farm 

 attached to the Agricultural College at Downton, where the soil 

 is light and calcareous, and at Ferryhill in Durham, where the 

 scil is heavy clay, and almost destitute of lime. 



