.S7A- \\'1LUAM SIEMENS, l-.R.S. 



433 



tin- material to be stitched. Latterly a certain confidence had 

 been created in favour of steel for rivet-making ; and great care 

 u;i> taken in producing rivet-steel of such a quality as would make 

 rfectly reliable. But what was the fact? Since rivet-steel 

 had been brought into the market, it was not sold for so high a 

 price as was given for the best rivet-iron. The latter cost as 

 much as 19 a ton, but for rivet-steel engineers went down at 

 once to the very cheapest quality they could get, which he might 

 mention was steel rolled from crop-ends, and with all the defects 

 of crop-ends about it. It was therefore unfair to criticise steel 

 severely, unless all the circumstances regarding it were known, 

 and al>ove all things unless it was known what price had been paid 

 for it. 



In the discussion of the Paj>cr 



"ON HARDENING IRON AND STEEL; ITS CAUSES 

 AND EFFECTS," by PROFESSOR AKERMAN, 



Du. SIEMENS* congratulated Professor Akerman on having 

 dealt with a subject which had puzzled all those who were practi- 

 cally engaged in the treatment of steel, and which had never yet 

 been sufficiently or scientifically explained. It would be impossible- 

 at a meeting like that to discuss all the matters brought forward 

 in the paper. There was, however, one leading idea running 

 through the whole, which was to the effect that carbon existed in 

 iron and steel, not in two conditions, as was now generally sup- 

 posed, but in three conditions, and that it was to this intermediate- 

 condition that the phenomena of hardening and tempering were 

 mostly attributable. Professor Akerman held that this inter- 

 mediate carbon travelled towards the graphitic condition when 

 steel was gradually cooled, and that this furnished the key to the 

 somewhat striking changes that arose if they took an ingot of 

 steel, hardened it, and then subjected it to the processes of 



* Excerpt Journal of the Iron and Steel Institute. 1880, p. 437. 



VOL. I. F F 



