EFFECT OF FUEL, FLUXES, TEMPERATURE, ETC. 303
upon the amount of sulphur in the fuel, the silicon and manganese in the iron, the flux and the heat in the cupola. An increase of the sulphur in the fuel or flux will cause a corresponding- increase of sulphur in the iron; while the less fuel used and the better a cupola is fluxed or '' hot iron '' produced, the less sulphur will the re-melted iron contain.
The reduction or oxidation of silicon is greater the higher the blast pressure and also the hotter the iron is melted. In a general way, it can be said that silicon is reduced from one to three-tenths of one per cent, and sulphur increased from one to six hun-dredths of one per cent., where the fuel holds .80 to i.oo in sulphur. The author has, in a few rare cases, found the silicon to be but very little reduced, but never found a re-melt where the sulphur was not materially increased. The increase of one point of sulphur can often neutralize the effect of ten to fifteen points of silicon, and hence, owing to the increase of sulphur being so powerful in neutralizing the effects of silicon, it is very essential that all conditions influencing the increase of sulphur should be guarded and controlled so far as practical, in order to be best assured of obtaining any desired results in the castings.
The changes due to manganese in re-melting iron are toward its reduction. The hotter the metal, the higher the blast, the greater its reduction. The reduction can range from 10 to 30 points. The more manganese iron contains, the less the increase of sulphur, owing to the affinity manganese possesses for carrying off sulphur in the slag.
Phosphorus may be called a '' sticker,'' as when once absorbed by iron it cannot be easily eliminated.sile strength of 50,000 to 60,000 pounds per square inch is claimed. The author has endeav-give a softer re-melt than gray parts of the same casting, see pages 338 and 339.