which conjlltute Crude Iron and Steel. 147 



Caft fteel requiring more hardnefs, with, of 



charcoal, - —5th part. 



Steel capable of {landing a few blows, but quite 



unfit for drawing, - - y-glh 



Firft approach to a fteely granulated fradlurc, is 



from - 1 I r,th to ^th 



White call iron - - tt^ 



Mottled caft iron - - *^th 



Carbonated caft iron - - T V ta 



And fupercarbonated crude iron - tV*^ or 



when any greater quantity is ufed. 



Although this is the quantity of charcoal neceffary to form 

 thefe various qualities of metal by this mode of fynthefls, 

 yet we are by no means authorized to conclude that this is 

 the proportion of real carbonaceous matter taken up by- the 

 iron, feeing that in experiments No. I. to No. VI. inclufive, 

 the weight gained by the iron was upon the average equal 



only to — ^-th part; whereas the charcoal which djfap- 



2 Ho 



peared in the different fufions amounted to 61. 1 per cent, of 

 the original quantity introduced along with the iron. 



In the fucceeding experiments the following differences 

 are remarkable : 

 No. VII. Charcoal ufed 

 No. VIII. 

 No. IX. 



No.X. 



No. XI. 



No. XII. 



No. XIII. 



No. XIV. 



From this we fee that when a proportion of charcoal equal to 

 T ^th part, and above, the weight of the iron is ufed, the latter 

 always gains in weight; but when a more fparing proportion 

 is introduced, room is left for the exertion of another affinity 

 upon the metal, and it consequently and invariably lofes in 

 weight proportioned to the diminution of the carbon. I have 

 here further to remark upon the foregoing experiment, and 

 upon the nature of experiments by fynthefls performed in 

 this way in general, that the refults as to quality will differ 

 materially when different portions of matter are ufed. So 

 that an operator repeating the above experiments cither in 

 , Vol. XIII. No. 50. L crucibles 



