96 



Mr. C. J. Lundstrom. 



5591 — 5580 in the Ulfshytte spectrum. Lecoq* gives fainter bands 

 belonging to this spectrum at 5538 and 5436, which correspond to 

 the lines 5540 and 5433 which were observed on one occasion. 



The lines that I have pnt in the fourth column of the table as 

 being derived from CaO and K agree as with the position of lines in 

 other spectra which have been described as belonging to CaO and K, 

 but cannot with certainty be ascribed to them. In the same manner 

 it is uncertain whether the line with X = 6108 belongs to Li or not. 



Finally, it may be remarked that 5642 agrees as to its position 

 with one of the strongest lines in the sulphur spectrum, and that 

 some of the bands in the band spectra of carbon have a certain 

 correspondence, though the strongest bands are missing. 



As to the spectrum during the warming of the converter, two 

 bands may be ascribed to CaO, the rest being of unknown origin. 



With increased knowledge of these band-spectra, and of the 

 effects of temperature and of pressure upon them, I hope that the 

 mystery which at present surrounds the cause of their appearance in 

 different works during different periods of the " blow " will admit of 

 full explanation. 



IV. 



On the Practical Use of the Spectroscope in the Bessemer " Bloiv." 



That the spectroscope in most cases puts a sharp mark on the 

 moment of complete decarbonisation was established long ago, but 

 whether it can be nsed at all with the method we have in Sweden 

 of stopping the " blow" just as the Bessemer metal has so altered in 

 composition as to contain no more than the desired percentage of 

 carbon is more difficult to decide. 



At Nykroppa the object was to obtain a percentage of carbon as 

 high as 0'85, at Hagfors as low as 0*15, while at Langshyttan it was 

 required to be 65. During a considerable period the changes of the 

 spectrum at the end of every " blow " were observed, and the aspect 

 of the characteristic groups were recorded as carefully as possible 

 just at the moment of the interruption of the " blow." 



The following table (p. 98) shows the aspect of the spectrum under 

 normal conditions. 



By means of these rules I tried to direct the " blow " and get a 

 metal with 0"65 per cent, of carbon. The result of the first twelve 

 " blows" was metal containing 0-70, 0*50, 1*50, 0*65, 0*65, 0*60, 0'65, 

 0-75, 0-65, 0-60, 0'65, 0"60 per cent, of carbon. 



It may be observed here that a group of rays sometimes disappears 

 and soon appears again with diminished brightness. The error in 

 the value of No. 3 was due to uncertainty in observing, but with 

 some practice such an error may easily be avoided. 



* ' Les Spectres Lumineux,' par Lecoq de Boisbaudran, p. 189. 



