﻿8 Prof. Silliman on the Examination of the Bessemer Flame 



flash of the sodium. It is very faint at first, but soon becomes 

 quite distinct, and lasts through the blow. The vivid flashing of 

 the sodium-line may be accounted for by the exceedingly small 

 amount of sodium required to produce its spectrum, an amount 

 not exceeding yqooo ooo~o °f a g ram » The slightest momentary 

 combustion taking place in the stream of gas from the converter 

 would at that instant render glowing a sufficient amount of the 

 vaporized sodium to produce its spectrum, and thus occasion the 

 flashes so characteristic in the first appearance of that line. 

 Lithium exists in a much smaller quantity, and requires ^ o o ooo o 

 of a grain, or thirty times that given for sodium. By the time 

 the lithium-line is established the red potassium-line at 23J° 

 and, occasionally, the violet line at 135° appear, and the blue and 

 green fields become divided into bands which are so rapidly re- 

 solved into bright and dark lines that it is difficult to note the 

 exact time of the appearance of each. The spectrum increases 

 to a dazzling brightness, and extends itself in both directions 

 until it reaches from 23J° to 140°. 



During the third period the spectrum becomes more brilliant 

 and the lines more distinct. Several new lines make their ap- 

 pearance in different parts of the spectrum, of which the ones at 

 51^°, 57°, and 67° are well defined, while others are faint and 

 not always visible, some of them appearing only toward the 

 close of the last period. In viewing the lines in the most re- 

 fracted part of the spectrum, it has been repeatedly observed, 

 both by myself and others, that these lines were more strongly 

 marked when entering the eye at an angle than when viewed 

 directly. That this was not imagination is proved by repeated 

 identification of lines at the same point on the scale. 



At the termination of the blow the lines are rapidly swept 

 away, sometimes in the inverse order of their appearance, but 

 more generally they disappear within the space of two or three 

 seconds, leaving a continuous spectrum as at first, though some- 

 what brighter. Sometimes the sodium- and lithium-lines are 

 swept away with the others, and at other times they remain 

 visible. In either case the change is very decided, and does not 

 generally occupy more than three seconds. In the course of my 

 observations thirty-three lines have been detected, as given in 

 the Table below. 



Some of the lines given by Lielegg I have failed to find, but 

 have detected others not given by him. 



1st Period : 23|, 35, 50, 135. 



2nd Period : 23i 35, 43, 44, 44J, 45±, 46, 47J, 48J, 50, 52, 

 53, 56, 56i, 61 i ; 62, 62J, 63, 65, 66J, 67J, 70, 

 72,120,135. 



