392 THE SCIENTIFIC PAPERS OF 



into effect by some of my licensees for converting old iron rails of 

 mixed or doubtful parentage into steel rails. 



The facility thus offered to steel manufacturers introduces, 

 however, a danger upon which the steel user will have to fix his 

 attention. A steel rail containing from 1 to 1| per cent, of 

 manganese may look well and resist the tests for toughness and 

 strength which are usually applied, and may yet contain more 

 than \ per cent, of phosphorus or sulphur, or both these sub- 

 stances. It is only at temperatures below the freezing-point that 

 the presence of phosphorus will make itself felt by symptoms of 

 cold shortness, and it would therefore certainly not be advisable to 

 put down rails of this description in cold climates. 



For the construction of ordnance and other high class purposes, 

 more than a trace of manganese in the metal is, in my opinion, 

 decidedly objectionable. Manganese, though very efficacious in 

 hiding impurities in the steel, is in itself an impurity inconsistent 

 with high quality of the material produced. Its admixture with 

 the metal is purely mechanical, and upon analysis of different 

 portions of the same ingot it is found that its distribution is very 

 irregular. Being more oxidizable than iron, a metal containing a 

 considerable percentage of manganese cannot be re-heated without 

 deterioration ; is pitted by exposure to sea-water ; and its strength 

 and toughness are also found to be below those of really pure 

 metal when subjected to crucial tests. It is important, therefore, 

 that steel for war purposes where high temper and great tensile 

 strength is required, should be practically free from manganese, 

 as well as from all other admixtures, with the sole exception of 

 carbon. Extra mild steel, which is so remarkable for its extreme 

 ductility, should contain in 100 parts 99*75 parts of metallic iron, 

 and only 0'25 per cent, of all foreign substances put together. 



It is for the production of these special qualities of steel that 

 the open^hearth process has come into extensive use, being 

 employed, either wholly or partially, by many of the leading works 

 both in this country and abroad. The total production of open- 

 hearth steel (both the Siemens-Martin and Siemens variety) 

 amounted in 1877 to 275,000 tons, since which time its produc- 

 tion has gone on increasing, notwithstanding the extreme depres- 

 sion which continues to prevail in the iron and steel trades. 



The French Admiralty were the first to take up the subject of 



