ana Iron- Sf ones by Viijlon. 183 



In a former paper I mentioned, that if iron-ftones were 

 fmelted without the addition of any other fubftance, the pro- 

 duft in iron would be proportioned to the quantity of lime 

 contained in the refpeftive clafles. We ihall fee from the 

 following experiments how far this is confirmed by means 

 of the aflay-furnace, and furnifh to ourfelves one important 

 lelTon, How far the various mixtures of ores afFe6t the ope- 

 ration of fmelting ? 



I ft. Into a crucible, with a well- fitted cover, I introduced 

 875 grains of a pulverifed filiceous iron-ftone in its raw ftate, 

 and applied fuch degree of heat as is ufually given in fuch 

 operations. In twelve minutes I found that the iron-ftone 

 was in perfeft fufion, much agitated, and emitting large 

 bubbles of ignited gas of a fiery colour. In forty minutes 

 the crucible was vi'ithdrawn ; the furface of the vitrid fluid 

 ftill continued to boil, and emit bubbles, though in lefs quan- 

 tity. In this ftate I introduced a fmall rod through the fcoria, 

 and difcovercd the forface of a button of metal. The mo- 

 ment it came into conta<Sl with atmofpheric air, a beautiful 

 combuftion took place; the metal rofe in a fpiral form 

 to fupply the rapid inflammation, and continued till the 

 fcoria (ftill in fufion) clofed over the furface of the button. 

 When cold, I found a perfect formed button of extremely 

 oxygenated crude iron, which weighed 219 grains; a pro- 

 duce equal to 25.1 per cent, from the raw iron-ftone. The 

 fcoria obtained was of a fliining black colour, firm and pon- 

 derous, and weighed 402 grains ; fo that the lofs in volatile 

 matter was 254 grains, equal to 29 per cent. 



Although this iron-ftone was filiceous, yet I am convinced 

 the lofs of volatile matter would have been greater, had not 

 nearly one-half of the whole contents of iron remained in 

 the fcoria, united with oxygen, at the rate of 35 /)^r <r^w^. 

 I found the produce of the metallic button thus obtained 

 while as filver, and prcfenting impcrfeft radii; the furface 

 was confidcrably oxydatcd, cfpecially where the combuftion 

 bad taken eiTc6l. 



N 4 ad, I 



