414 Ari Account of some ExperimeMs 



vflience he concluded that the carbon necessary to convert th« 

 iron into steel had not been furnished, as Clouet supposed, bv 

 decomposition of tlie carbonic acid, but that it had found its 

 v,-av from the ignited gas of the furnace to the iron. This re- 

 sult occasioned suspicions of the accuracy of the deductions 

 trom the experiment with the diamond ; and Mr. Mushet ac- 

 cordingly, at the suggestion of the editor of The Philosophical 

 Magazine, repeated the experiment made at the Polytechnic 

 School, only keeping out the diavwnd. The results (for he made 

 several experiments) uniformly gave him good cast steel, whence 

 he concludes that we are still without any satisfactory or con-' 

 elusive proof of the stcelification of iron solely by means of the 

 diamond ; and adds that lie doubts whether the diamond af- 

 forded even one particle cj' cur I on to the iron. The details of 

 both Clouet's and Mushet's experiments may be found in 

 the fifth volume of The Philosophical Magazine Sir George 

 M'Kenzie repeated both Clouet's experiments, and those of 

 Mr. Mu-shet, and obtained results confirming the conclusions of 

 the French chemist. The labours of this gentleman indeed seem 

 sufficiently conclusive; but, if a doubt should remain, it occurred 

 to Mr. Pepys, that the battery would afford an experimentum 

 CTVcis on the subject ; and his ingenuity readily suggested a 

 mode of making it, every way unobjectionable. He bent a wire 

 of pure soft iron, so as to form an angle in the middle, in which 

 part he divided it longitudinally by a fine saw. In the opening 

 ?o Termed, he placed diam.ond powder, securing it in its situation 

 by two finer wires, laid above and below it, and kept from sliift- 

 ing, by another small wire, bound firmly and closely roimd them. 

 All the wires were of pure soft iron, and the part containing the 

 diamond powder was enveloped by thin leaves of talc. Thus 

 arranged, the apparatus was placed in the electrical circuit, 

 ^vhen it soon became red hot, and was kept so for six minutes. 

 The ignition was so far from intense, that few who witnessed 

 the experiment, expected, I believe, any decisive result. On 

 opening the wire, however, Mr. Pepys fijund that the whole of 

 the diamond had disappeared ; the interior surface of the iron 

 had fused into numerous cavities, notwithstanding the very mo- 

 derate heat to which it had been exposed; and all that part 

 which had been in contact with the diamond was converted into 

 perfect blistered steel. A portion of it being heated red and 

 plunged into water, became so hard as to resist the file, and to 

 scratch glass. This result is conclusive; for as the contact of 

 any carbonaceous substance, except the included diamond, was 

 effectually guarded against, to that alone can the change pro- 

 duced in the iron be referred. This experiment will also pro- 

 bably 



