470 Prof. McLennan and Mr. Ireton on Fundamental 



diameter. Another brass cylinder, 2*8 cm. in diameter and 

 7 cm. in length, was supported in the centre and coaxiallv 

 with KL by means of three brass plugs placed between the 

 cylinders. The inner cylinder contained a quartz tube F 

 about 7 cm. in length. A coil of nichrome wire MN was 

 wound around this tube, and the ends were led through 

 openings fitted with small porcelain plugs in the bottom 

 of KL. A layer of asbestos paper was placed around the 

 wire, and tire whole space between the quartz tube and brass 

 cylinder packed with asbestos powder. When the gas was 

 lighted a clear Bunsen flame was maintained above the 

 mouth of the burner. The metals to be vaporized were 

 placed within the quartz tube F, and the furnace was raised 

 to whatever temperature was desired by applying a current 

 of suitable strength to the circuit MN. The photographs 

 were taken with a large Hilger quartz spectrograph, type C. 

 Wratten and Wainwright Panchromatic plates manufactured 

 by the Eastman Kodak Co. of New York were used. 



The spectrograms taken are shown at the end of this 

 paper. No. 1, fig. VI. (PL XIV.) is a reproduction of the 

 spectrum of the zinc spark taken from a condensed discharge. 

 No. 2 was obtained with zinc vapour in the Bunsen flame, and 

 No. 3 shows the spectrum of the Bunsen flame free from the 

 zinc vapour. In addition to the ordinary Bunsen flame spec- 

 trum, spectrogram No. 2 shows that the zinc line A, = 307<r03 

 A.U. came out strongly. This is well shown in No. 2 of the 

 enlarged reproduction in fig. VII. (PI. XV.). In no case did 

 the flame spectrum show any trace of the line \ = 2] 39*33 

 A.U. Some experiments were also made with calcium, 

 using the same type of Bunsen burner, and No. 1, fig. VIII. 

 (PL XIV.) is the spectrogram of the calcium arc in vacuo, 

 taken with an arc-lamp similar to the type described by 

 McLennan and Henderson*. No. 2, fig. VIII. is a spectro- 

 gram of the Bunsen flame fed with calcium vapour. In 

 addition to the ordinary flame spectrum, it shows the calcium 

 line X = 4226-91 A.U. of frequency v = (V5, S)— (2, P). 

 Another line is shown at about \ = 4059 A.U., but this line 

 must have been due to an impurity in the calcium metal, as 

 no line is given at this wave-length by Eder and Valentat- 

 No. 3, fig. VIII. is n spectrogram of the ordinary Bunsen 

 flame. 



Since the line X = 2288'79 A.U. came out in strong flames 

 with cadmium vapour, it was thought the corresponding line 



* McLennan and Henderson, loe. cit. 



t Eder and Valenta, Atlas Typischer -Spektren, Wien. 



