On the presence of Phosphorous in Pig-iron. 423 



that " the assertions which I [yourself] have made are demon- 

 strable in every case without special experiment, and are 



absolutely incontrovertible, as well as incapable of verification, by 

 experiment or observation on diamagnetics." 



Most of what I have to say upon this subject condenses itself 

 into one question. 



Supposing a cylinder of bismuth to be placed within a helix, 

 and surrounded by an electric currentof sufficient intensity ; can 

 you say, with certainty, what the action of either end of that cy- 

 linderwould be on an external fragment of bismuth presented to it ? 



If you can, I, for my part, shall rejoice to learn the process by 

 which such certainty is attained: but if you cauuot, it will, I think, 

 be evident to you that the verb " must " is logically " defective/^ 



We knoio that magnetized iron attracts iron : we know that 

 magnetized iron repels bismuth : this, so far as I can see, is your 

 only experimental ground for assuming that magnetized bismuth 

 repels bismuth, and yet you affirm that an action deduced from 

 this assumption " is demonstrated with as much certainty as the 

 parallelogram of forces/' Do I not state the question fairly ? 

 I can, at all events, answer for my earnest wish to do so. 



It is needless to remind one so well acquainted with the 

 mental experience of the scientific inquirer, that the very letters 

 which you attach to your sketch, page 291, may tempt us to an 

 act of abstraction — a forgetfulness of a possible physical differ- 

 ence between the n of iron and the n of bismuth — which may 

 lead us very wide of the truth. The very term 'pole' often 

 pledges us to a theoretic conception without our being conscious 

 of it. You are also well aware of the danger of shutting the 

 door against experimental inquiry on an unpromising subject ; 

 and when you apparently do this in your concluding paragraph, 

 I simply accept it as a strong way of expressing your personal 

 conviction, that the action referred to is too feeble to be rendered 

 sensible by experiment. 



Believe me, dear Sir, 



Most truly yours, 



John Tyndall. 



LX. On the supposed Influence of the Hot-blast in augmenting 

 the quantity of Phosphorus in Pig-iron. By David S. Price 

 Ph.D., F.C.S.; and'E. Chambers Nicholson*. 



THE employment of the hot-blast in the smelting of iron is 

 admitted to occasion the production of pig-iron of inferior 

 quality, that is to say, contaminated with larger amounts of 

 foreign elements than that smelted with cold-blast. 



* Communicated by the Authors. This paper was read in part at the 

 British Association, Liverpool, 1854. 



