Then mix with this powder a flux composed of three parts of Nitre fixed with Tartar, one part of fusile glass, and half a part of Borax and charcoal-dust. The dose of this reducing flux must be thrice the weight of the ore. Put this mixture into a good crucible; cover it with about half a finger thick of Sea-salt; over the crucible put its cover, and lute it on with Windsor-loam made into a paste with water. Having thus prepared your crucible, set it in a melting furnace, which you must fill up with charcoal. Light the fire, and let it kindle by gentle degrees, till the crucible become red-hot. When the decrepitation of the Sea-salt is over, raise your fire to the highest by the blast of a pair of perpetual bellows, or rather several. Keep up this intense degree of heat for three quarters of an hour, or an whole hour, taking care that during all this time the furnace be kept constantly filling up with fresh coals as the former consume. Then take your crucible out of the furnace; strike the pavement on which you set it several times with a hammer, and let it stand to cool: break it, and you will find therein a Regulus of Iron covered with slag. _OBSERVATIONS._ Iron ore, like all others, requires roasting, to separate from it, as much as possible, the volatile minerals, Sulphur and Arsenic, which being mixed with the Iron would render it unmalleable. Indeed it is so much the more necessary to roast these ores, as Iron is, of all metallic substances, that which has the greatest affinity with those volatile minerals; on which account no metallic substance whatever is capable of separating it from them by fusion and precipitation. Fixed Alkalis, it is true, have a greater affinity than Iron with Sulphur; but then the composition which a Fixed Alkali forms with Sulphur is capable of dissolving all metals. Consequently, if you do not dissipate the Sulphur by roasting, but attempt to separate it from the Iron by melting the ore with a Fixed Alkali, the Liver of Sulphur formed in the operation will dissolve the martial part; so that after the fusion you will find little or no Regulus. All Iron ores in general are refractory, and less fusible than any other; for which reason a much greater proportion of flux, and a much more violent degree of fire, is required to smelt them. One principal cause why these ores are so refractory is the property which Iron itself has of being extremely difficult to fuse, and of resisting the action of the fire so much the more as it is purer, and further removed from its mineral state. Among all the metallic substances it is the only one that is less fusible when combined with that portion of phlogiston which gives it the metalline form, than when it is deprived thereof, and in the form of a calx.