28 



Mr. J. N. Lockyer. 



[Dec. 18, 



into the lower part of the flame, the green double (X 5687'2 and 5681*4) 

 and the flntings were not seen, either with or without the spark. 



Experiment No. IV. — Same arrangements as No. II, with, metallic 

 sodium, and with, a small blowpipe instead of Bunsen. 



In this experiment the flame spectrum showed, besides the yellow 

 line (D), the green double (X 5687'2 and 5681*4), and also the flutings 

 in the green, those in the red being absent. As soon as the spark 

 was passed, the green double (X, 5687*2 and 5681*4) became brighter,, 

 while the flutings vanished. 



In these observations the sodium was put into the flame just below 

 the platinums. When put into the bottom of the flame, the D line was 

 seen alone. 



Experiment No. V. — A glass tube inch in diameter was prepared T 

 about 6 inches in length, having two platinums sealed into it at a 

 distance of 4 inch.es from each other. A bulb was blown at each end r 

 so that the spectrum might be examined with the tube end-on. A 

 piece of sodium was put into the tube, and the latter exhausted with 

 a Sprengel pump. An Argand burner was placed at one end of the 

 tube, in order that the absorption of the vapour, as well as its radiation y 

 might be observed. The metal was then very gradually heated by a 

 Bunsen flame. 



After the heating had gone on for about twenty minutes the absorp- 

 tion line of D appeared ; this gradually increased in intensity. 



On passing the spark along the tube, the bright lines of sodium 

 appeared, the green double (\ 5687*2 and 5681'4), being distinguish- 

 able after D had been seen for a little time alone. 



The temperature was now increased and the absorption spectrum 

 again examined. The flutings in the green gradually made their 

 appearance, D increasing in intensity, the green line being invisible. 

 Afterwards the flutings in the red came in. 



On passing the spark the absorption spectrum, consisting of the red 

 and green flutings disappeared instantaneously, and the green double 

 was seen very bright ; after the passage of the spark D dark was much 

 increased in breadth. 



The quantity of hydrogen given off during the change prevented 

 the passage of the spark, and the observations had to be discontinued. 

 As soon as some of this had been pumped out the same observations 

 were repeated with the same results. 



Experiment No. VI. — An experiment was made with lithic chloride 

 in Bunsen flame, with the same arrangement as in Experiment No. I. 



The flame spectrum with the dispersion employed showed no Li line 

 except the red one (A, 6705*2). On passing the spark from the Holtz 

 machine, the yellow line (X 6102*0) and the blue line (X 4602*7) 

 appeared as bright as the red line. The same results were obtained 

 on repeating the experiment with the large induction-coil. 



