The manufacturers in iron are not so numerous as the karrankeas, but they appear to have studied their business with equal diligence.  The negroes on the coast being cheaply supplied with iron from the European traders, never attempt the manufacturing of this article themselves; but in the inland parts the natives smelt this useful metal in such quantities not only to supply themselves from it with all necessary weapons and instruments, but even to make it a article of commerce with some of the neighbouring states.  During my stay at Kamalia there was a smelting furnace at a short distance from the hut where I lodged, and the owner and his workmen made no secret about the manner of conducting the operation, and readily allowed me to examine the furnace, and assist them in breaking the ironstone.  The furnace was a circular tower of clay, about ten feet high and three feet in diameter, surrounded in two places with withes, to prevent the clay from cracking and falling to pieces by the violence of the heat.  Round the lower part, on a level with the ground—­but not so low as the bottom of the furnace, which was somewhat concave--were made seven openings, into every one of which were placed three tubes of clay, and the openings again plastered up in such a manner that no air could enter the furnace but through the tubes, by the opening and shutting of which they regulated the fire.  These tubes were formed by plastering a mixture of clay and grass round a smooth roller of wood, which, as soon as the clay began to harden, was withdrawn, and the tube left to dry in the sun.  The ironstone which I saw was very heavy, of a dull red colour with greyish specks; it was broken into pieces about the size of a hen’s egg.  A bundle of dry wood was first put into the furnace, and covered with a considerable quantity of charcoal, which was brought, ready burnt, from the woods.  Over this was laid a stratum of ironstone, and then another of charcoal, and so on, until the furnace was quite full.  The fire was applied through one of the tubes, and blown for some time with bellows made of goats’ skins.  The operation went on very slowly at first, and it was some hours before the flame appeared above the furnace; but after this it burnt with great violence all the first night, and the people who attended put in at times more charcoal.  On the day following the fire was not so fierce, and on the second night some of the tubes were withdrawn and the air allowed to have freer access to the furnace; but the heat was still very great, and a bluish flame rose some feet above the top of the furnace.  On the third day from the commencement of the operation, all the tubes were taken out, the ends of many of them being vitrified with the heat; but the metal was not removed until some days afterwards, when the whole was perfectly cool.  Part of the furnace was then taken down, and the iron appeared in the form of a large irregular mass, with pieces of charcoal adhering to it.