4i8 



NATURE 



\August 28, 1879 



processes of heating and hammering were attended with so much 

 difficulty that the attempt was given up. Here again Krupp 

 stepped in, and succeeded, thirty-two years ago, in manufactur- 

 ing cannon of cast steel, which unhappily have become ordinary 

 commodities with those nationalities who could afford such 

 expensive weapons. Since that time Krupp has produced about 

 2,000 guns, the heaviest being, when finished, 72 tons (16 inch). 



Sir William Armstrong and Sir Joseph Whitworth soon came 

 into the field with guns of their own invention. The former, 

 by adopting the system of iron coils applied externally to a 

 central cylinder ; and the latter, by shrinking cylindrical hoops 

 on to a central cylinder made of cast steel. 



In the adaptation of the steel manufacture of the cast or 

 crucible steel period to the production of every object demanded 

 by the march of engineering and mechanical science, I need not 

 mention the names of individuals and firms in this town who 

 have shown themselves equal to the task ; but I will venture to 

 say that their success has been nich as to raise the town of 

 Sheffield to the very pinnacle of fame as producing steel 

 of any, even the highest quality demanded in the markets of 

 the world. 



I must now turn to a name honoured everywhere for the 

 benefits and renown he has brought to his country by his 

 inventions and appliances, developed during the last twenty- 

 four or twenty-five years, in tlie manufacture of a steel which 

 can be cheaply produced and readily adapted to the requirements 

 of the purchaser. I am sure the audience will in their minds 

 anticipate the record of the name of Bessemer — a name which 

 will be handed down to posterity in connection with the manu- 

 facture of steel as long as that manufacture exists. 



Another name which will most deservedly figure in the 

 history of the development of the steel manufacture is one, like 

 that of Bessemer, which has been known not only in that develop- 

 ment, but in connection with many other discoveries in physical 

 science— I mean that of Siemens, who, like his compeer, has 

 not only invented processes, but has personally carried them out 

 into practical application. An expression let fall by the latter 

 as President of the Iron and Steel Institute at its meeting last 

 year in Paris, exhibits very strikingly the absence of any other 

 feeling on the part of these two great men save that of the most 

 friendly rivalry. 



Speaking of a comparison between the results of steel manu- 

 factured by the Bessemer blowing process and the Siemens- 

 Martin open-hearth process, Dr. Siemens said, " He did not see 

 how the result could be the same. It might be better in the 

 Bessemer process than in the open hearth for aughtlie knew, but 

 it could not be the same ; " and it seems to augur "well for the 

 advancement of science in our day that so little of a contrary 

 spirit is exhibited in the discussions which ensue from time to 

 time upon any improved process either chemical or mechanical, 

 having for its object the production of a better material at a 

 lower first cost. The name of Robert Mushet may very properly 

 be introduced here as one of our early inventors of the improved 

 processes for the manufacture of steel, and it is gratifying to find 

 that other countries besides England have learnt to appreciate 

 the results obtained by him dming so many years of scientific 

 and experimental research. 



It is needless that I should do more in an assembly like that 

 before me than refer, in the simplest terms, to the differences in 

 the processes of manufacture connected with these names. 



In that of Bessemer, pig-iron of a selected quality is charged 

 into what is technically called a "converter," a large cast-iron 

 vessel into which air can be blown at considerable velocity by 

 suitable blowing machinery. This goes on until the iron is 

 thoroughly oxidised, and the impurities contained in the metal 

 are driven off. When this happens the blowing ceases, and a cer- 

 tain proportion of Spiegeleisen or of ferro-manganese is added to 

 the charge so as to give the required amount of carbon. Blow- 

 ing recommences, this time only to effect complete mixture of 

 the materials, and then the casting of the ingots takes place of a 

 quality corresponding to the metal selected for the mixtures. A 

 mild steel — or, as it has been called, a pure iron — is the resultant, 

 and it is capable of being worked, welded, and hammered very 

 much as in the case of the purest wrought irons ; but it pos- 

 sesses generally a much higher tensile resistance and a greater 

 ductility. 



In the Siemens-Martin, or open-hearth process, a similar 

 charge of pig-iron of the desired quality — probably haematite 

 pig — is put into the bed of a reverberatory furnace of the rege- 

 nerative system, and the necessary oxidation is produced by 



adding to the molten mass iron ores, or oxides of iron in pro- 

 portions ascertained by experience, after which re-carbonisation 

 is obtained by the addition of ferro-manganese or Spiegeleisen 

 as in the Bessemer process. 



These processes have been the great factors in that reduction 

 in the cost price, and therefore in the extension of the use of 

 such objects as steel tyres, axles, shafts, rails, &c., to which X 

 have already referred, and which is so striking an instance of 

 the results which our men of science can accomplish by their 

 physical and experimental researches into the means of supplyii^ 

 the wants of our work-a-day world. 



I will now draw attention to another product of the steel 

 manufacture which is of immense importance, and which could 

 not have been obtained for ordinary purposes but for the facilities 

 of manufacture arising out of the inventions I have just alluded to 

 — I mean that of steel castings, i.e. castings obtained from the 

 crucible, precisely in the form in which they are to be used in 

 the construction of machinery, just as is the case in ordinary cast 

 iron ]run from the cupola furnace. This production of castings 

 for engineering purposes is gaining an enormous and rapid 

 development ; and when it is considered that in this metal we 

 obtain castings of a strength at least three to four times that 

 of the strongest iron castings, the importance of this experimen- 

 tal discovery can scarcely be over-rated. 



Nor must I pass over the application of these processes to 

 the production of boiler plates, bridge girder plates, and ship 

 plates, in which, as a result of the greater tensile resistance of 

 such plates (reaching for ordinary uses a figure of about twenty- 

 eight to thirty-four tons to the square inch), the engineer is not 

 only enabled to lighten his structure, but to expect from it greater 

 durability — an expectation not diminished by its greater capa- 

 bility of resisting corrosion, especially where care is taken to 

 exclude manganese from the mixture of the metals employed. 



For specific purposes, and where price is not so much an 

 element of consideration as great tensile or percussive resistance, 

 a more costly mode of manufacture has been adopted by Sir 

 Joseph Whitworth, whose attention was probably drawn to the 

 necessity for obtaining such a metal, during the construction of 

 cannon and torpedoes, but which 'has now been extended to 

 objects of a very varied character. The method of manufacture, 

 which has been in use upwards of ten years, is by casting ingots 

 under very heavy hydraulic pressures, from very carefully selected 

 materials, the result being the production of a metal of enormous 

 tensile resistance, reaching, in some instances, the high figure of 

 100 tons per square inch, while at the same time the bubbles 

 and air vesicles, which sometimes appear in metal produced in 

 the ordinary methods, are entirely or almost entirely got rid of, 

 and the consequent striations and imperfections of internal 

 structure and external surface disappear. 



It is hoped that ere long we shall be able to procure in this 

 way cylindrical boiler plates rolled solid from the ingot, much 

 after the fashion in which weldless steel tyres are now obtained, 

 and that the weakening of these plates by the existing necessity 

 for forming horizontal riveted joints may thus be avoided. 



It is desirable before closing this, I fear, already somewhat 

 long address, to call attention to the most recent development of 

 the steel manufacture as exhibited in the processes of Messrs. 

 Snellus, Gilchrist, and Thomas, by which iron containing a con- 

 siderable proportion of, say, I "44 per cent, of phospliorus, may, 

 in the course of its manufacture into either Bessemer or Seimens- 

 Martin steel, have this deleterious matter entirely removed, or 

 reduced to an inconsiderable proportion. 



The method of carrying out this operation was exceedingly 

 well described at the recent meeting of the Iron and Steel In- 

 stitute in London, and it was shown that where such irons were 

 melted in vessels lined with a slag having twenty per cent, of 

 silica and thirty per cent, of lime and magnesia, the phosphorus 

 was gradually and effectually absorbed by this lining, and a steel 

 of good quality, comparatively free from phosphorus and silica, 

 was produced. 



The result to the community will naturally be that, as hence- 

 forth a much more extended area of our iron fields both at home 

 and abroad will become available for the production of steel, 

 the use of that metal will be still further extended and its price 

 reduced mainly by means of the methodical researches of our 

 scientific metallurgists, and entirely independently of those 

 accidental combinations which have in less scientific days led to 

 the adoption of new and improved methods in the production 

 of metals required by the progress of mechanical and economic 

 science. 



