Basic Slag. 7T 



111 addition to the 46,000 tons of liigli -grade slag' — and it will 

 be remembered tliat, according- to our own definition, liig*li-grade 

 slag must contain not 15 but 16 per cent, of citric- soluble phosphoric; 

 oxide, and in the above table not only the citric-soluble but all the 

 phosphoric oxide is included — there w^as only 212,000 tons of lower- 

 g-rade slag that would have been allowed on our market at all even 

 under our relaxed war-time regulation No. 11. This (quantity would 

 not even suffice the British farme'-, and precludes all idea of export. 

 As for the 28,000 tons l)elow 5 per cent., it would not be worth 

 grinding. 



(2) As far as the second point discussed by the committee went, 

 it was estimated that (he farmers of the United Kingdom ought to 

 have been using 890,000 tons of basic slag annually, even before the 

 war. 



(3) Regarding the augmentation of the phosphate in the slag 

 from subsidiary sources («) some experiments were carried on by 

 adding rock phosphates in the proportion of h cwt. per ton of the 

 slag in the fused state, but there was not sufficient alteration of the 

 rock phosphate to justify the process, and the committee decided that 

 such an addition could only be justified if it improved the character 

 of the rock pliosi)hate added. \ b) The use of iron ore containing 

 more phosphorus or the addition of phosphates in the blast furnace 

 Avas considered, but from the steel manufacturer's point of view this 

 would add to the cost of production of the steel, and could, therefore, 

 be adopted only if the price of the resulting slag were sufficiently 

 attractive. The matter is still under consideration. (c) Another 

 point remaining under consideration is the reintroduction of the two 

 lowest grades of slag into the blast furnace so as to increase the 

 phosphatic character of the pig-iron, and thus produce a higher- 

 grade slag. 



(4) The committee arranged for experiments to be carried out at 

 Rothainsted to elucidate — 



{a) Whether the soluble and insoluble open-hearth slags differ 



in agricultural value, aiid, if so, whethei' some method of 



evaluation can be devised better than the present citric 



acid method ; 

 (J)) whether the present oj)en-hearth slags are inferior to (lie 



pre-war Bessemer slags -.vhen applied in (juantities of e((ual 



phosphatic content ; 

 (<■;) whether finely ground mineral phosphates differ greatly in 



value from basic slag; 

 {d) whether the manurial effect of basic slag is wholly dependent 



on its phosphate content, oi whether other constituents 



(manganese, etc.) should be considered of value. 



Up to six months ago no conclusion had been arrived at on the 

 first three of these points, and on the fourth the results lent no 

 support to the idea that manganese is of value. 



The Question uf Solubility. 



In the January, 1922, issue of the Journal of the Ministiij of 

 Agriculture " Dr. E. J. Russell says that " in days before the war 



