228 JONES-STRONG— THE ABSORPTION SPECTRA [April 24, 



to the Nernst glower, the current being 0.8 amperes and the sht 

 width 0.20 mm. The length of exposure to the spark was 4 mins. 

 Starting with the strip nearest the numbered scale the temperatures 

 were 6°, 17°, 31°, 49°, 63°, 74° and 82°. 



The general effect of the addition of calcium chloride is to make 

 all the bands hazier, and to increase the transmission throughout the 

 region of the band. At 6° there is a slight transmission throughout 

 the ultra-violet portion of the spectrum. As the temperature is 

 raised this general transmission is decreased, and at 82° practically 

 no light passes through the solution of shorter wave-length than 

 A2800. Sharp bands occur at A 3464, A 3500, A 3535, A4276 and 

 weak diffuse bands at A 4295, A 4305, A 4340, A 4445, A 4620, A 4695, 

 A 4760, A 4825, A 5095, A 5 130, A 5225, A 5260, A 5320, A5710, to 

 A 5860, A 6245, A 68 10 and A 6900. 



At 82° the bands in the A 3500 region are slightly more intense 

 than at 6°. Practically all the bands from A 4200 to A 5200 have be- 

 come much weaker at the higher temperature. This is especially 

 true of the band A 4276, its intensity being less than half what it is 

 at 6°. Most of the bands are shifted to the red with reference to the 

 same bands at 6°. For instance, A 5095 is shifted 5 Angstrom units 

 towards the red. The bands A 4695, A 4760 and A 4825 are all 

 shifted to the red at the higher temperature, and especially A 4825, 

 the shift in thise case amounting to 5 Angstrom units. In the case 

 of these bands the shift is not an apparent one due to unsymmetrical 

 broadening, for in this instance there is no broadening at all. 



The band from A 5710 to A 5860 at 6° has widened very unsym- 

 metrically and has the limits A 5710 to A 5920. The short wave- 

 length side is quite sharp and its position is practically independent 

 of the temperature. The long wave-length edge is quite broad and 

 recedes quite rapidly towards the red as the temperature is raised. 

 The bands in the red AA6810 and 6900 grow fainter and fainter 

 with rise in temperature, and have practically disappeared at 82°. 

 The band A 6245 is very weak at 6° and has disappeared at about 60°. 



It will thus be seen that not only does the presence of calcium 

 chloride modify greatly the absorption of neodymium chloride, but 

 that it changes the effects due to temperature very fundamentally. 

 In pure neodymium chloride practically no bands decrease in in- 



