﻿4 Prof. Silliman on the Examination of the Bessemer Flame 



but, as in the flame of the Bunsen burner, the hottest part is in 

 its outer sheath ; the conditions of combustion in both being 

 similar, it is probable that that part of the flame occupied by the 

 cone is at a lower temperature than that surrounding it. 



The green streaks in the flame are most intense when the 

 manganese spectrum is brightest ; and as the colour of the flame 

 when the Spiegeleisen is added is also green, we are led to sup- 

 pose them due to the presence of manganese. 



On two occasions simultaneous observations were made with 

 the spectroscope and the coloured glasses ; but, with the excep- 

 tion of that just mentioned, and the changes at the commence- 

 ment and termination of the blow, no striking coincidence was 

 noticed. 



II. Examination with the Spectroscope. 



The science of spectrum-analysis is yet in its infancy ; and 

 there has been no scientific investigation, perhaps, which has 

 been more contradictory in its results than that of the Bessemer 

 flame. The first application of the spectroscope to the analysis 

 of the Bessemer flame was made in ] 862, by Dr. Roscoe, at the 

 works of Messrs. John Brown and Co., in Sheffield. Soon after 

 this it was in constant use in Brown's works for controlling the 

 process. It was next introduced at Crewe, and from there is 

 said to have been taken to Seraing, in Belgium, in 1865. 



Roscoe's account of the general appearance of the spectrum 

 has not altogether been verified by subsequent observers. His 

 not having seen any line beyond 80° indicates an imperfection 

 in his instrument. He also is the only one who claims to have 

 seen the sodium-line as an absorption-band, or who professes to 

 have detected the lines of nitrogen and hydrogen in the Bes- 

 semer spectrum. His spectroscope was so arranged that the 

 spectrum of the Bessemer flame was seen in the upper half of 

 the field of view, while the spectrum with which it was to be 

 compared was seen immediately below. The spectrum of the 

 flame was thus compared with the following spectra : — 



1. Spectrum of electric discharge in carbonic-oxide vacuum. 



2. „ strong spark between silver poles in air. 



3. „ „ „ iron „ 



4. „ „ „ „ hydrogen. 



5. Solar spectrum. 



6. Carbon spectrum — oxyhydrogen blowpipe supplied with ole- 



fiant gas and oxygen. 



The coincidences observed were very few, and totally failed 

 to explain the value of the Bessemer spectrum. The lines of 

 the well-known carbon spectrum did not occur at all, either as 



