354 'TH-E SCIENTIFIC PAPERS OF 



was brought into the furnace would produce a full welding heat if 

 it was continued, yet the essential work done was accomplished at 

 its own temperature, just as water would be evaporated at its own 

 temperature in a boiler, whatever might be the intensity of the 

 heat applied outside. Probably to this circumstance was attribut- 

 able the fact that the iron when taken out of the furnace was 

 really free from phosphoric acid. But he attributed in large part 

 this freedom from phosphoric acid in the iron to the circumstance 

 that the phosphorus was combined in the ore very often combined 

 with oxygen and lime as phosphate of lime, and to the fact that 

 it would take a greater heat to disturb this compound which 

 already existed than would suffice to retain the phosphorus in com- 

 bination with metallic iron after having been combined with that 

 metal in the blast furnace. This argument would lose its force 

 probably if the time allowed for these reactions was unlimited, and 

 it must further be borne in mind that the final chemical reaction 

 in both the puddling and direct process did not probably exceed a 

 quarter of an hour, during which dephosphorization would go on 

 in the one and phosphorization in the other process to a limited 

 extent. No one would be better able to judge than Prof. 

 Williamson to what extent this question of time might be expected 

 to influence the final result in the two processes. 



Before proposing a vote of thanks to Mr. Bell for his valuable 

 communication, he would reply very shortly to some of the 

 remarks that had been made with reference to the paper he 

 had had the honour to bring before the Institution. Mr. Ridley 

 wished him to explain how it was that in dealing with an ore 

 containing much phosphorus he should be able to get an iron 

 free from phosphorus, whereas in the puddling furnace a cinder 

 containing 5 or 6 per cent, of phosphoric acid would readily com- 

 municate that phosphorus, or a portion of that phosphorus, to the 

 iron. In dealing with chemical processes they had, of course, to 

 take into account all the circumstances of temperature, and the 

 relative proportion in which the substances liable to act upon one 

 another existed. Now, he explained yesterday that in treating 

 poor ores, and poor ores containing a great deal of phosphoric acid, 

 in a rotatory furnace, such as the one erected at Towcester, care 

 was taken that a very fluid cinder was the immediate result of the 

 heat acting upon the mixture. The first action of the heat upon 



