PREFACE 



BY E. J. RUSSELL, D.Sc., F.R.S. 



Director of the Rothamsted Experimental Station 



HE utilisation of basic slag in agriculture is an excellent example 

 of the help that modern science affords to the working farmer. A 

 waste product of steel-making, resulting from a modification by 

 Thomas and Gilchrist in 1878 of the Bessemer process, it was at first 

 considered worthless and thrown on the refuse heap. The late Prof. 

 John Wrightson made field experiments in 1884 and 1885 at Ferryhill 

 and at Downton, and showed that the material had noticeable fer- 

 tilising value: this discovery was confirmed and developed by the 

 systematic pot experiments of Paul Wagner at Darmstadt, which 

 began in 1885 and continued for several years afterwards. Extensive 

 field tests were made during the 'nineties by Sir (then Professor) 

 J. J. Dobbie and Prof. D. A. Gilchrist at Bangor, and by Prof. W. 

 Somerville and later on by Sir T. H. Middleton at Cockle Park, with 

 the result that a considerable body of information was accumulated 

 as to the effectiveness of basic slag under the various conditions 

 obtaining in practice. This has already been summarised by Prof. 

 Somerville in the Journal of the Board of Agriculture for 1911, 1918, 

 etc. 



Some ten years ago, however, it became evident that the basic 

 open hearth process would be a serious competitor with the Bessemer 

 process, and chemical examination showed that the slag, though 

 correctly described as 'basic slag,' was altogether different from 

 the material with which the agriculturist had become familiar. The 

 upheaval caused by war and post-war conditions gave an enormous 

 impetus to the open hearth process, and it is now extending to so 

 many works that before long the older process will probably cease 

 to be operated. 



This result is of course distinctly awkward for the agriculturist who 

 sees a valuable f ertiliser disappearing, and being replaced by one which 

 is more costly and at first sight seems to be nothing like as good. 



Dr Scott Robertson has the great advantage of being in close 

 touch with the steel-making industry, and at the same time of being 

 able to carry out agricultural experiments. At the outset of his in- 

 vestigations he made a careful selection of the types of slag likely to 



