426 ]\Iessrs. Price and Nicholson on the Influence of the Hot-blast 



amount, whilst in 3 and 4 it falls considerably short. That 

 this is owing to the length of time during which the reduction 

 process is carried on we have no doubt, as we have frequently- 

 repeated the assays with the same proportions, and have found 

 the amount of phosphorus in the button to vary considerably, 

 never having succeeded in obtaining more than four-fifths of the 

 total quantity. If, however, the cementation were prolonged 

 for a sufficient length of time, it is very probable that the whole 

 of the phosphoric acid would be reduced. 



We have undertaken many expeiiments upon the large scale 

 with the view of deciding this pomt. For this purpose we have 

 determined the amount of phosphorus in iron that had been 

 smelted from argillaceous ores by cold-blast, and by a blast 

 heated to 600" F. 



The following are the results : — 



I. II. III. IV. 



Hot-blast . . . 0-74 0-68 0-71 0-58 



V. VI. VII. VIII.* 



Cold-blast . . . 0-81 0-62 0-68 0-63 



The iron in both cases was what is known as good No, 2 

 foundry pig. 



In two instances it will be seen that the per-centage of phos- 

 phorus is higher in the cold-blast iron than in the hot ; but the 

 difference in these and in the other two is so slight, that it may 

 fairly be attributed to the variations in the composition of the ore. 

 The slags produced simultaneously with four of the above irons 

 were examined for phosphoric acid by the usual methods, as well 

 as by molybdate of ammonia ; and it was only by the latter re- 

 agent that we were able to find minute traces. We append the 

 analyses of the slags : — 



I. II. V. VI. 



Silicic acid .... 39-95 40-20 41-64 42-94 



Alumina 17-41 16-45 13-20 16-29 



Lime 29 64 3000 35-91 31-10 



Magnesia 6-47 729 4-21 4*16 



Protoxide of iron . . . 0-24 0-57 0-11 0-34 

 Protoxide of manganese . 0-91 0-84 0-74 0-51 

 Sulphide of calcium . . 3-60 2-71 2-19 2-16 



Alkalies 1-46 1-30 1-70 1-87 



Phosphoric acid . . . trace trace trace trace 

 Loss 0-33 0-64 0-30 0-63 



100-00 100-00 100-00 100-00 



* These correspond with tlie per-centage amounts of phosphorus calcu- 

 lated from the analyses of the ores, that the pig-iron should contain if all 

 the phosphoric acid were reduced. 



