36 ON CAST IRON. 



judge from appearances, confifted chiefly in carburet of iron. 

 Not removable We attempted to remove it; but asfome of the metal adhered 

 for adhering to j^ anc i cam e away at the fame time, we defifted. Soon 

 after, the furnace being clofed, we heard a continual boiling, 

 refembling that of a vifcous fubftance in a clofe veflel. On 

 The metal was opening the furnace, we perceived that the whole matter in 

 brought to ebul- reality boiled, and that bubbles were continually rifing, which 

 Carburated hi- burft on the furface with a beautiful bluith flame. Thefe jets 

 drogen gas evol- of flame had the colour exhibited by carburated hidrogen gas. 

 The boiling continued as long as the fire was kept up ; at the 

 fame time a pretty large quantity of fcoria was formed, which 

 however could not be removed, on account of the vifcous con- 

 fidence now acquired by the metal. Befides, as the metal was 

 frequently ftirred to prefent a frefli furface to the air, the fco- 

 ln five hours it ria mingled with it. At the end of five hours it was no longer 

 became white fluid, and appeared to be refined. It had loft its gray colour 

 grained, an d finenefs of grain, was white and coarfe grained, and 



and a little mal- fhowed itfelf more malleable, though it was not capable of be- 

 This^was after- m S f° r g e d. The refiner carried it to his ordinary furnace, and 

 wards refined there it was refined in lefs time, and required lefs labour than 

 foonerthan com- common cafl ; 

 mon caft iron. . 



As in this trial we were unable to feparate the lcoria, and 



refining °iron in no change had been made in the form of the hearth of the 

 a reverberatory common refinery, which ought perhaps to have been done, 

 nothing poiitive can be advanced with refpeel to the practical 

 advantage of refining by the help of reverberatory furnaces ; 

 we were merely convinced of its poffibility, and enabled to 

 demonftrate the theory of this procefs, that is to fay, of feeing 

 ft • th tear- c ^ ear 'y wnat paffed in the operation. The caft iron was here 

 bon is burned converted into malleable by means of the oxigen that was in 

 oft# / the little atmofpheric air, which, jointly with azote and car- 



bonic acid gas, covered the metal in fufion. This oxigen 

 combined with the carburet of iron, and then carbonic acid 

 gas and oxide of iron were formed; this produced the bubbles 

 of air and the fcoria. The lightnefs of the frothy fcoria, which 

 arofe to the furface at the beginning, was the reafon of their 

 leparation from the reft of the mafs j but as foon as the air be- 

 gan to act they were deftroyed. 



Second 



