238 



THE SCIENTIFIC PAPERS OF 



tion exceeding one and a half millions of tons, and a money value of 

 about nine millions sterling. 



Notwithstanding its great national importance and the in- 

 teresting chemical problems involved, the puddling process has 

 received less scientific attention than other processes of more 

 recent origin and inferior importance, owing probably to the mis- 

 taken sentiment that a time-honoured practice implies perfect 

 adaptation of the best means to the end and leaves little scope for 

 improvement. 



The scanty scientific literature on the subject "will be found in 

 Dr. Percy's important work on iron and steel. Messrs. Grace, 

 Calvert and Richard Johnson, of Manchester,* have supplied most 

 valuable information by a series of analyses of the contents of a 

 puddling furnace, during the different stages of the process. These 

 prove that the molten pig metal is mixed intimately, in the first 

 place, either with a molten portion of the oxides (or Fettling) which 

 form the lining or protecting covering to the cast-iron tray of the 

 puddling chamber, or with a proportion of oxide of iron in the 

 form of hammer slag or red ore thrown in expressly with the 

 charge ; that the silicon is first separated from the iron ; that the 

 carbon only leaves the iron during the " boil " or period of 

 ebullition ; and that the sulphur and phosphorus separate last of 

 all while the metal is " coming to nature." 



The investigations by Price and Nicholson, and by M. Lan, 

 confirm these results, from which Dr. Percy draws some important 

 general conclusions, which have only to be followed up and supple- 



* "Phil. Mag.," Sept. 1857. The following Table, from Messrs. Calvert and 

 Johnson's Paper, includes the chief results of their investigations : 



