Oji the differ e7it 'Proportions of Carhon, ^c. 3 23 



nity betwixt iron and carbon which conftitutes the ^ndlefs 

 varieties of this metal. 



To invoftigate this fiibje6l with accuracy, it appeared to 

 nie that a feries of experiments, made by the fufionofbar 

 iron with well prepared charcoal of wood in veflels completely 

 air-tight, would be produ6live of the greateft nicety of re- 

 fult. With this view, the proportions of iron and charcoal 

 recorded in the following experiments were each of them in- 

 troduced into crucibles of Stourbridge clay while the clay 

 was yet moift. The top was accurately clofed upon the con- 

 tents, and the crucibles fet aiide to dry for eight or ten days. 

 Previous to the introduction into the melting furnace they 

 were baked in a common annealing fire to bring them to an 

 ordinary red heat: from this furnace, while hot, they were 

 fucceffively placed in the alTiy-furnace for reduAion. 



The following are the details of thefe experiments : Grains. 



Exp. I. Pieces of S wed i(h iron - - il73 



Charcoal ', or - grs. ^Sl^ 



The mixture was expofed to a moderate degree 

 of heat for 70 minutes, when the crucible was 

 withdrawn. When cold it was carefully exa- 

 mined, and found free from cracks. 

 Charcoal untaken up, of a deep black colour, 3iOr 



Charcoal difappeared in the fufion - 271 



equal to 48 per cent, of the original quantity. 



The button obtained was fupercarbonated crude iron, 



and weighed - _ , ^ li'i<i 



Gained in weight, by the combination of carbon, 60 

 equal to .,',th part fully of the firll weight of iron. 



The fraiMurc of ihi.s button was exadly that of No. I. pig 

 iron, towards the upper furface largely granulated ; and be- 

 low, a fubdratum of ftnall grained metal refembling; No. JIL 



P'g 'f""- . Grains. 



Total weight of the mixtures « I754r 



Charcoal remaining 310^ grains. 



Iron obtained - 1233 gr^iins. 1543 



Total lofs in fufion ail 

 The quantity of charcoal which difappeared in this operation 



was equail to — -th part the weight of the iron. ^ . 



4,r ° Grams. 



FjA-p. TI. .Swedifh bar iron - - 1093 



Charcoal |, or - grs, 273 j 



Xa The 



