On Prhnary Ores of Iron. 361 



any time in contact with external air, either in the procefs 

 of cementation for fteel, or in the de-oxygenation of iron- 

 ores. Iron-ores thus Stratified, expofed to a ftate of complete 

 ignition, would in 8 or 10 hours nearly part with the whole 

 amount of mixtures, including oxygen, with which they 

 were combined ; the ore would be found penetrated with * 

 confiderable portion of carbon, and the metal exifting iiva ftate 

 nearly difengaged. Their tendency, however, would much 

 depend upon the various mixtures which compofed the in- 

 dividual ores; their lofs of weight, their properties and 

 appearance, alfo depending upon fimilar circumftances with 

 thofe explained in the preparation of iron-ftone in a former 

 paper. 



The varieties of the primary ores of iron found in this 

 country are much limited, and chiefly poflfefs the fame ex- 

 ternal characteristic forms — at leaft thofe which have come 

 within my knowledge — that of the iiland of Iflay excepted. 

 Cumberland and Lancashire feem to be the two great depo- 

 sits for this mineral. The ore of the former is found in 

 laro-e maffes, fplinty, and globulatcd, confiding of various 

 kidney forms and haematites, ftriatcd and Smooth, of blueifh 

 and reddifti colours. The kidneys are frequently large, com-, 

 pofed of fucceffive layers encrufting a nucleus of coarfer 

 ore. The fplinty pieces are of a light blueifh colour, and 

 frequently afford the molt beautiful Specimens of various 

 cryltals, principally of a whitifh colour, of a chalky, and. 

 Sometimes of a pellucid appearance ; alio garnet, more or 

 lefs intenfe, and green. The moft common Shapes are pen-< 

 tao"onal and hexagonal pyramids, with truncated bafe?. 

 Some of thefe I have found meafure 1 inch at the bafe • 

 from this uncommon Size, down to the moft minute forms 

 imaginable, the fame figures are found poSTeSIing purity, 

 tranfparency, and finiSh in the higheft degree : thefe clafTes 

 are of a whitifh water colour, more or lefs pellucid. Garnet 

 colpurcd cry (tub are found of the fame Shape, but of a very 



fmall 



