3S4 Oa the AJfay'tng of Ores hy Pujtori^ 



by the fufion of an ore_, and from what fource this pfopfcrty 

 is derived. 



Upon a fomier occafion I have mentioned that iron, ob- 

 tained from ai'gillaceous ores, pofl'cflcd a degree of ftrength 

 beyond tliat obtained from the other genera. This trutll 

 daily prefents itfelf to our obfcrvatiun in the large fcale of 

 manufacture 5 and however erroneous the reafoning of the 

 manufaAurer as to the caufc, yet fo evident arc the confe- 

 quences produced, that we muft immediately attribute them 

 to fome fource bevond the cafualties of operation in the 

 fmehing furnace. In the explanation of this faft, as on the 

 degrees of oxygenation and carbonation in general, the ma- 

 nufafturer has rccourfe to the exiftent nature of the iron 

 in the ore, and denominates the metal contained in fuch and 

 fuch an ore to be " ftrong, coarfe, ilUmelting iron ;" of 

 ^^ weak, tender iron, poflefling no body." That iron-ftones 

 and ores yield, in the operation of fmehing, diflerent quali- 

 ties of crude iron, as to ftrength, is an undeniable faft; and 

 that the fame varietv attaches to iron when converted to 

 malleabillfv is a truth daily evinced in our forges • yet thefe 

 l'at5ls bv no means entitle us to conclude, without farther in- 

 veftigation, that thefe varieties of llrengtii are the hereditary 

 property of the priftine formation of the metal. This in- 

 ference accords w ith a haftv view of the matter, and a bare 

 comprehenfion of eft'ci^l^s, without tracing to its fource the 

 niodifving principle of the whole. The theory which I 

 have adopted, and which in every Itep I have found fup- 

 ported bv numerous experiments, upon difierent fcales, and 

 bv a long- courfe of praAical obfervation, explains to me, 

 with much more cafe and harmony, the whole phenomena 

 of quality in ores and iron-ftones. 



To illuftrate that part of my theory relative to ftrength, 

 let the preceding experiment, wherein carbonated crude iron 

 was produced from the oxyde of pure iron, be repeated with 

 the addition of a little pure clay. If the clav added be half 

 the weight of the lime alfo ufed, the iron will be found, 



when 



