On the Component Parts of Iron -f ones. 107 



nature impofed upon crude iron in the blaft-fumace by 

 the development of its mixtures, moil commonlv accom- 

 panies it through all its fubfeqiient ftages of exiftence as a 

 metal. 



3. I hofe iron-ftones whofe component parts are nearly an 

 equalifed mixture of clay, lime and fand, which torrefy with 

 a flight degree of adhefion to the tongue, afluming a dark- 

 red or brownifh colour, void of internal fibre, always afford, 

 with the local proportion of fuel, iron of an intermediate 

 quality for fufibility and foftnefs, but generally pofieflincr 

 ftrength in an eminent degree. Such iron is excellently 

 adapted for the manufacture of great guns, mortars, and the 

 large fpecies of machinery. Its application to the purpofe of 

 bar-iron making, would alfo be attended with the moft bene- 

 ficial efle&s, pofleffing neither the extreme of fufibility nor 

 of infufibility : it would greatly prevent, in the manufacturing, 

 a tendency, which iron pqffefled of thefe extremes has, iq 

 become red or cold fhort. 



4. Iron-ftones which unite a large proportion of fand wifh 

 fparing proportions of clay and lime, which, upon being 

 (lightly expofed to heat, exhibit mafles of femivitrification, 

 neither obedient to the magnet, nor adhefive to the tongue, 

 having a refractory difpofition to part, and pofleffing a dark- 

 blue or black colour, always afford, with the ufual pro- 

 portion of fuel, crude iron of the worft quality, either as tq 

 ftrength or fufibility. Such metal is commonly highly oxy- 

 ginated, and brittle; incapable of being ufed alone for any 

 melting purpofe ; and, when applied to the ufe of the forge, 

 affords malleable iron, which pofleffes the cold (hort quality. 



Thefe are the four principal claffes under which I have 

 arranged our iron-ilones, with regard to their tendency to 

 afibrd their iron carbonated, pofleffing ftrength, or othcrwife, 

 when fmclted in the blaft-furnace with a determinate quan- 

 tity of fuel. As this claflification is exactly analogous to the 

 p fu!u obtained in f,he large way, it may ferve as a ground, 

 '^ work 



