8 



Cold blast iron, with a load of 448 lbs., continued to increase 

 in deflection, and ultimately broke, after sustaining the 

 weight 35 days. 



All the hot blast iron bars broke in the act of loading them 

 with the above weight of 448 lbs. 



Notwithstanding these and many similar facts brought out 

 by the experiments in question, certain portions of them are 

 constantly being quoted for the purpose of proving that iron 

 made by hot air is stronger than that produced by the use of 

 cold air. 



Contemporary with these experiments on a small scale, 

 others of far greater importance have been going on ; thus we 

 hear of hundreds of railway chairs, cast from iron made by 

 the improved process, constantly breaking, where tens only 

 broke before ;t of steam engines and other valuable machinery 

 breaking in rapid succession, and in parts where, by regular 

 work, they were never known to give way before the intro- 

 duction of the improved iron ; of the more respectable por- 

 tion of millwrights being obliged to make new calculations, 

 and a new stock of patterns, in order to lessen, as far as is 

 in their power, the enormous losses and the great disappoint- 

 ment of their friends by such breakages. We hear of coal- 

 masters of whole districts, and other prudent and humane pro- 

 prietors of large establishments, introducing clauses in their 

 contracts for castings, stipulating that no hot blast iron shall 

 be used therein; and at length the same has become common in 

 contracts for gas and other pipes, which it has hitherto been 

 usual to make of the most inferior quality of irons, it having 

 been found that the sockets of some miles of piping have 



t In a paper recently read before the Institution of Civil Engineers, Mr. Mac- 

 neill states that on the Dublin and Drogheda Railway, where chairs were used 

 made of hot blast iron from Scotland, the breakage was very great, as compared 

 with those on the South Eastern Railway, where they were made of cold blast 

 iron, and that, in his opinion, the latter would be cheaper than the former at 

 an increased price of £4 per ton. 



