212 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Sir Frederick Abel, who presented them to Dr. John Hopkinson. The 

 tests upon the first ring by Messrs, Pocklington and Lydall seem to 

 show that they did not anneal the iron ; the remarkable measurements 

 of Wilson upon the second ring were made after the iron had been 

 softened. Norway Iron (R) was a long annealed rod about half an inch 

 in diameter. This was tested in a solenoid. An analysis of Hopkin- 

 son's ring made by the Whitworths, showed manganese 0.143 per cent, 

 phosphorus 0.271 per cent, sulphur 0.012 per cent, carbon 0.01 per cent 

 and "slag " 0.436 per cent. The Elswick iron contained 0.1 per cent 

 of manganese and 0.013 per cent of sulphur but no phosphorus and 

 hardly a trace of carbon or other impurity. Norway Iron (Q) was an 

 annealed ring cut from a bar of " pure iron " obtained in the Boston 

 market. 



My thanks are due to Professor John Trowbridge, who furnished me 

 with the pure iron described above, and to the Trustees of the Bashe 

 Fund of the National Academy of Sciences who loaned me some of the 

 apparatus used in the work. 



The Jefferson Laboratory, 

 Cambridge, Mass. 



