WILLIAM SIEMENS, F.R.S. 



425 



mithor had spoken of certain brands of material of certain 

 s, for instance by a firm like Krupp's. Now, he happened to 

 know that Kriipji made steel by at least three different processes, 

 and it was difficult to say by what process the particular bar was 

 produced that had been referred to in the paper, nor, if the pro- 

 cess were known, could it be affirmed what were the materials used 

 in its manufacture. If it was a cheap material, probably Mr. Krupp 

 would have put in some cheap iron, and the result might be a bar 

 that would give a very fair absolute strength, but would give way 

 to a bending and breaking test before its time ; whereas if he 

 knew that the metal would be tested very severely, he would pro- 

 duce something that would be capable of resisting very high im- 

 pacts. Some years ago Dr. Siemens made a series of experiments 

 on the power of materials of particular composition to resist blows 

 at different temperatures. His object was to see what effect phos- 

 phorus had on mild steel with regard to that quality. From those 

 experiments he had arrived at the conclusion that the power to 

 resist blows in mild steel, at any rate, was dependent almost 

 entirely on the presence or absence of phosphorus. It was well 

 known that phosphorus might be counteracted in the steel, to a 

 great extent, by the addition of manganese ; but let the steel be 

 cooled down to freezing point, or below, and the metal would 

 break short : whereas true mild steel, containing only traces of 

 phosphorus and of manganese, would be affected to a very slight 

 ex cent by any depression of temperature to which it might be 

 subjected. He believed that pure metal was influenced very little 

 by changes of temperature, whereas metal containing foreign 

 matters, and particularly phosphorus, would be influenced to a 

 great extent. It would, therefore, be erroneous to draw general 

 conclusions from such experiments as were given in the paper. 

 The author seemed to have attempted to find out results without 

 the chemist; but the chemist now-a-days would put his finger 

 into everything. If they called a thing iron, he would call it a 

 mixture of iron, phosphorus, sulphur, silicon, carbon, and other 

 earthy materials, and it was useless to try to do without him. 

 They must work hand in hand with him in order to arrive at such 

 results as would guide them safely in their practice. 



