lo,# On the Component Parts oj ' lron-jlon£s. 



Befides thefc (wo leading inftruments of alteration in the 

 fmelting proccfs, inherent in and derived from the mate- 

 rials, good and bad effects may be produced from an unjutc 

 proportion and quality of the lime-ftone, which is added, in 

 order that the proper equilibrium may be reftored, and the 

 iron properly and beneficially revived. 



Taking this then for a general principle, that the crude 

 iron contained in all iron- (tones is the fame, arid that it can 

 be called into exiftence as a metal of all the various degrees 

 of carbonation, by regulating the proportion of fuel, and of 

 the folventj I (hall proceed to mention thofe mixtures 

 which I have always obferved determine the future quality of 

 the crude iron. 



I . Argillaceous iron-ftone having fine clay as its chief com- 

 ponent earth, lime in the next proportion, and both thefe 

 nearly deftitute of fand ; which, when properly torrefied, 

 exhibits fibres on its internal fur face, of a brown, dark- 

 brown, or claret colour, running either in lireaks or radi- 

 ated, and adhering tenacioufly to the tongue, will afford, 

 with a moderate proportion of coaks and lime-ftone, iron of 

 the fineft quality, pofiefiing itrength conjoined with an inti- 

 mate degree of fufibilitv. 



%. Calcareous iron-ftone, that which contains lime as its 

 principal earthy mixture ; holding clay in the next propor- 

 tion, and both thefe comparatively unallayed (totally they 

 never are) with fand; which, when regularly torrefied, af- 

 fumes a variety of (hades generally lighter in the colour 

 than the former clafs ; which fometimes, and fometimes 

 not, prefents internal fibres, and which adheres lefs teria- 

 cioufly to the tongue ; always contains iron, which can be 

 revived, richly carbonated with a comparatively fmall quan- 

 tity of coaks, and with a trifling addition of lime. Under 

 this clafs of iron-ftones are found thofe which produce iron 

 of a fufible nature, feldom connected with ftrength, but va- 

 luable for its utility in fine callings, which require ornament 

 more than durability. It is alfo from this fource of mixture 

 thai I would trace the red fhort quality of bar-iron. The 

 { nature 



