WILLIAM SIEMENS, J-'.K.S. 



443 



;itil difference U-lween cinder in iron and the scale of steel. 

 The cinder in iron was a glassy substance, which was a dielectric, 

 and therefore had no effect upon the corrosion of the metal, 

 us the scale on steel, which was produced in rolling, had 

 y deteriorating influence ; it was a magnetic oxide, which was 

 i \v to the steel, and wherever the metal was exposed in the 

 nee of such magnetic oxide, corrosion took place rapidly. 

 Au'iiin, if the scale should be rolled into steel plates, as was 

 sometimes the case, rapid corrosion ensued, for the same reason. 

 But he need hardly say that with proper care those causes of 

 undue corrosion could be and were prevented, and the extensive 

 use to which steel was now put proved sufficiently that there was, 

 at any rate in ordinary practice, no such destructive effect going 

 (in. The author stated that those interested in steel had been 

 singularly negligent in not following up the question of corrosion. 

 Being himself much interested in steel, Dr. Siemens had for some 

 years caused a running set of experiments to be carried out by 

 .Mr. Willis, the chemist at Landore, which told a very different 

 story from the author's. In one series, extending over six 

 months, made partly in a boiler supplied with salt water, and 

 partly by exposure in a tidal river the plates being exposed to 

 the air for six hours, and then immersed for six hours in salt 

 water the result was in some instances of open exposure slightly 

 in favour of iron, but, in the cases of boilers, always very 

 much in favour of steel. He had just received a report from 

 Mr. Willis, in which reference was made to a point of importance, 

 the perfect cleaning of the surfaces. It had been found that if 

 the surfaces were carefully cleaned of oxide by dipping the plates 

 in the first instance in an acid solution, the corrosion was always 

 much diminished. The evil effects of scale on steel were pointed 

 out at the Institution of Naval Architects,* by Mr. Barnaby, on 

 the 5th of April, 1871), when he clearly showed that the magnetic 

 oxide scale was very deleterious in its effects. He believed that 

 it was now the practice of the Admiralty to clean the scale on" 

 before using the plates for shipbuilding. During the past week 

 he had received a number of letters, quite unsolicited, from 

 gentlemen interested in the use of steel, all speaking in the most 



* Vide Transactions of the Institution of Naval Architects, VoL XX. p. 225. 



