HENRY BESSEMER. 201 



produced gradually loses its small remaining portion of carbon, 

 and passes successively from hard to soft steel, from softened 

 steel to steely iron, and eventually to very soft iron ; hence, at 

 any certain point of the process, any quality may be obtained." 

 It was, however, found in practice that this remarkable 

 peculiarity of the Bessemer process constituted its principal 

 defect. Thus it was extremely difiScult, if not impracticable, to 

 determine with certainty when the decarburisation had pro- 

 ceeded to the desired extent, and to the exact point at which 

 the blast was to be stopped. If arrested too soon, no 

 dependence could be placed on the result, as the metal might 

 be only one-half or three-fourths converted, according to chance; 

 while, if continued till the iron was quite decarburised, it would 

 be burnt and comparatively worthless. The workmen could 

 only judge by the appearance of the flame — first violet, then 

 orange, then white — issuing from the mouth of the vessel, wher 

 it was proper to interrupt the process. But the eyesight of the 

 workmen was not to be depended on ; and as the stoppage of 

 the blast ten seconds before or ten seconds after the proper 

 point had been attained would produce an altogether different 

 result, it began to be feared that, on this account, the Bessemer 

 process, however ingenious, could never come into general use. 

 Indeed, the early samples of Bessemer steel were found to 

 exhibit considerable irregularity : the first steel tyres made of 

 the metal, tried on some railways, were found unsafe, and their 

 use was abandoned ; and the ironmasters generally, who were 

 of course wedded to the established processes, declared the 

 much-vaunted Bessemer process to be a total failure. It was 

 regarded as a sort of meteor that had suddenly flitted across 

 the scientific horizon, and gone out leaving the subject in more 

 palpable darkness than before. 



