1879.] On a New Method of Spectrum Observation. 27 



higher heat-level, and shows the important bearing on solar physics 

 of the results obtained by this new method of work. 



In the flame the two least refrangible of the components of b are 

 seen associated with a line less refrangible, so as to form a triplet. 

 A series of flntings and a line in the bine are also seen. 



On passing the spark, all these but the two components of b are 

 abolished. We get the wide triplet replaced by a narrow one of the 

 same form, the two lines of b being common to both, thus — 



Flame Spectrum 

 (End of Flutings) 



Spark Spectrum 



When the line in the bine disappears on passing the spark, two new 

 lines are seen. The spark lines are in the snn, bnt the less refran- 

 gible member of the wide triplet and the bine line seen in the flame 

 are absent. 



The following are the details of some of the experiments which 

 have been made on the above points : — 



Experiment No. I. — Two pieces of platinum wire were supported in 

 a Bunsen flame at a distance from one another of about 3 millims. 

 They were then connected with a Holtz machine-, in order that the 

 spark might be passed inside the flame. 



An image of the platinums was then thrown on the slit of the spec- 

 troscope by means of a lens. The spectroscope used had two dense 

 flint prisms of 60°. 



A piece of charcoal soaked in solution of sodic chloride was pnt 

 into the base of the flame first, and then just below the platinum, and 

 the spectrum observed ; it consisted simply of the yellow line D. The 

 spark was passed and the spectrum again observed ; it now consisted 

 of D plus the lines of hydrogen and some air lines, the red and green 

 N~a lines and the green flutings being still absent. 



Experiment No. II. — Same arrangements, except that a large induc- 

 tion coil was substituted for the Holtz machine. The same results 

 were obtained with the sodic chloride. 



Experiment No. III. — Metallic sodium was next tried. It was found 

 that when the metal was put into the flame just below the platinums 

 the green line and the flutings were seen without the spark, that is, 

 at the ordinary temperature of the flame. On introducing the sodium 



