﻿10 Prof. Silliman on the Examination of the Bessemer Flame 



withstanding the fact that the illuminating-power of flames of 

 the same temperature varies with the composition of the gas, 

 because there is evidently enough sodium in the flame to give its 

 characteristic line ; hence, whatever might be the illuminating- 

 power of the flame, if the heat is sufficiently intense, the sodium- 

 line will show itself. 



Dr. Wedding adopts the theory that the absence of the spec- 

 trum at the beginning and termination of the blow is because 

 the absolute quantity of the bodies volatilized producing the 

 spectrum is at these times too small. His reasons for holding 

 this view are as follows : — et A trace of sodium will give its cha- 

 racteristic line ; but, according to Simmler, a much larger quan- 

 tity of manganese is needed to obtain a recognizable reaction than 

 that which can be detected by the well-known blowpipe reaction 

 with carbonate of soda. Consequently spectrum-analysis does 

 not depend alone upon the presence of a body, but also upon the 

 presence of a certain quantity. And although manganese is 

 always left in the iron, it may not be left in sufficient quantity 

 at the termination of the blow to produce the spectrum, and for 

 this reason the lines disappear.'''' 



To this theory there are some strong objections. 1st. If we 

 take manganese in sufficient quantity and hold it in a flame, the 

 spectrum will increase in brightness until a uniform temperature 

 is attained; but when the amount of manganese vaporized 

 begins to diminish, its spectrum will gradually decrease in 

 brightness until it disappears. Now, if the disappearance of 

 the manganese-lines in the Bessemer spectrum is owing to the 

 diminution of the quantity of manganese, we should infer that 

 these lines would gradually grow more indistinct and then fade 

 away ; but, on the contrary, the manganese-spectrum increases 

 in brilliancy from its first appearance, and is more intense just 

 before being swept away than at any other time. The analysis 

 of the smoke, which appears when the flame ceases, proves that 

 a considerable quantity is still volatilized; and it is notable that 

 in manganiferous iron this quantity increases towards the close 

 of the blow. 2nd. It would be more difficult to account by 

 this theory for the non-appearance of the sodium-line at the 

 beginning of the blow, as sodium then in all probability exists 

 in the issuing gas in sufficient quantity to produce its spec- 

 trum at a high temperature, as it is only by special precaution 

 that we can keep it out from any flame. 3rd. A still greater 

 difficulty would arise in applying this theory to the spectra of 

 sodium and lithium at the close of the blow. As has before 

 been stated, these lines sometimes disappear at the moment of 

 complete decarbonization, and sometimes remain. In the former 

 case, to say that our friend sodium had given out would be 



