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25 or 30 per cent, of ferric oxide we called it an ore of iron, though 

 a very poor one, for all metnllurgical purposes. These three oxides 

 differed very largely froui one another in many of their properties 

 and qualities. By a few simple experiments, he could make the 

 chemistry of this part of the subject clearer to them. The first 

 oxide was unknown in its free state, but in the precipitate they saw 

 it in combination with a molecule of water or as a hydrate. In the 

 tubes he had some very nearly pure iron, which he had prepared 

 from its oxide by means of hydrogen. The metal was thei-e in a 

 state of very fine division. He shook it out on a piece of warm 

 metal. It took fire instantaneously, and, in burning, became the 

 oxide known more commonly as rust. The iron had, in fact, 

 rusted very quickly. In the place of the brilliant metal, we had a 

 mass of reddish earth. In this solution iron was dissolved in an acid. 

 The addition of a little alkali would separate the iron from the 

 acid, and the precipitate was the same oxide as had been produced 

 by the union of the iron with the ox3'gen of the air. Once more he 

 would plunge steel wire into a vessel of oxygen. The ir<m was now 

 glowing white hot, and the globule was a compound of iron and 

 oxygen, in the proportion of three of the metal to four of the gas. 

 It was very different from the othei's, being black instead of red, 

 and, besides, it was magnetic. But they would, perhaps, ask if these 

 thi'ee oxides formed the basis of all the ores of iron, whence all the 

 perplexing variety of specimens on the table before them ? The 

 answer was, these ores diffei'cd from one another mainly in the 

 combinations of the oxides with the elements of water, with carbonic 

 acid, and with one another. 



It would be better, perhaps, to take the specimens in order, and 

 explain them as he went on. The greenish-grey stone was a 

 specimen of the celebrated Cleveland iron-stone. It was a protoxide 

 of iron combined with carbonic acid. The oyster shell imbedded 

 in the mass told of its marine formation. It was, in fact, from the 

 lias. It might give them some little idea of the enormous extent 

 to which this stone was worked, when he told them that, according 

 to the Government returns, out of the 12,000,000 tons of stone 

 raised in Great Britain in 1871, no less than 5,i00,000 tons were 

 from the Cleveland district. It contained about 32 per cent, of 

 iron. Much of the best Staffordshire ore was also a carbonate, and, 

 as they would see, resembled in colour, though not in texture, the 



