CONSTANT AND CHANGEABLE METALLOIDS, ETC. 13! cannot effect a change in the grade of an iron. Variations of either of these two elements can change the grade similar as variations in silicon or sulphur, but we must look to the furnaceman in preparing his mixtures of ores, etc., when making iron. If he desires an iron high, medium, or low in manganese or phosphorus, he can generally obtain it so evenly, in iron below 3.00 per cent, silicon, as not to affect in a practical way the grade of the iron which he desires to obtain, as long as the furnace uses the same ores, fuel, and fluxes. On the other hand, the silicon and sulphur • may vary considerably at times. However, future advancement in obtaining more uniform temperatures and distribution of blast in a furnace, which is now being gradually secured by some, will bring about improvement in this line. Nevertheless, silicon and sulphur will always be the metalloids which will most largely change the grade of iron to a greater or less degree where the same ores, fluxes, and fuels are used. Changes in the total carbon. It is thought by some furnacemen that the higher the temperature, and the more slowly the ore passes down in its reduction to iron, to the hearth of a furnace, the greater total carbon will be found in like irons. However, the author has failed to find where there were changes in total carbon, by the use of the same ores, etc., sufficient to radically change the grade of iron. Ores from the same mines or locality are liable to differ in their composition sufficiently to occasionally change the percentage of manganese and phosphorus, to some extent, in the same brand of iron. Nevertheless, such changes would generally call for an alteration of about half of one per cent, in manganeseths of the Warwick Iron Co. of Pottstown, Pa. is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................ 2,720 "