536 Experiments and ObfervationS 



ciently metallic upon the furface to receive a confiderable de- 

 gree of polifh from a file. The interior of each piece, from 

 the want of a fufficientdofe of heat, remained in a foft, eafily 

 pulverifed form, perfectly magnetic, and burning with great 

 rapidity when ltrewed in the flame. 



The apparent advantages which feemed to refult from this 

 chance difcovery were fufficient to induce me to perform, 

 during the courfe of three or four years, feveral hundred ex- 

 periments. In the profecution of this fubject, I foon aban- 

 doned the ufe of iron-ftones. It was found requifite to ufe 

 them in a roafted ftate ; and even afterwards, when heated in 

 contact with charcoal for three or four days, it was with the 

 greatefl difficulty that the procefs of malleability could be 

 made to penetrate to the centre without a general and pre- 

 mature fufion, which was always carefully to be avoided. 

 When raw iron-ftone was ufed, it was difficult to pre- 

 vent it from entering into fufion, and Separating its iron in 

 the (late of minute globules of crude iron. Having thus 

 fatisfied myfelf of the precarious refults obtained in this pro- 

 cefs by the ufe of iron-ftones, I had recourfe to Cumberland 

 ore, as a fit fubllitute, and my expectations in it were not 

 difappointed. 



I fhall fimply ftate the methods which I ultimately followed 

 to produce bar-iron in this procefs with the ufe of pit-coal 

 and charcoal of wood, Having prepared a fmall furnace 

 with an oblong cavity, furrounded with a fufficient number 

 of holes to admit the heat all round, I introduced 50 to 60 lbs. 

 of Cumberland iron ore reduced to pieces of nearly 3 ounces 

 weight each. This was mixed with a fufficient quantity of 

 clean duft produced in the charring of coal. The ore was 

 furrounded by a layer nearly 3^ inches thick, and this laft of 

 all was covered with a layer of moift fand % to 3 inches thick. 

 The fire was maintained at a temperature of nearly ioo° of 

 Wedgewood for 36 to 48 hours, according to circumftances. 

 It was then allowed to cool gradually. Upon examination, 

 the pieces of ore were frequently found attached to each 

 other fo firmly as to require confiderable force to part them. 

 They filed, and were, when the cementation was continued 

 long enough, malleable throughout. The ore, thus prepared, 

 was piled up in a flat broad fhallow crucible with a loofe 

 top, and placed in a furnace heated with the flame of pit- 

 coal. A welding heat was brought on the whole mafs, 

 which was then carried to the hammer: the firft blow de- 

 (i roved the crucible, and the ore was fhingled into a bloom at 

 the firft heat. 



}n this way excellent iron, was produced. Its fracture was 



light 



