I909] OF VARIOUS SALTS IN SOLUTION. 221 



peratnre there is complete absorption of the shorter wave-lengths to 

 A 3650. A blue-violet absorption extends between A 4050 and A 4450. 

 Following this band are three strong bands of about equal intensity 

 and each almost 100 Angstrom units wide. Their wave-lengths are 

 approximately AA4590, 4760 and 4970. Following is a band at 

 A 5500, a wide band from A 6400 to A 6630 and a rather narrow 

 band at A 6740. 



The absorption does not change very greatly until a temperature 

 of 60° is reached. Above this temperature the increase in absorp- 

 tion is quite rapid as the temperature rises. At y2)° the ultra-violet 

 band has widened to A 3800, the blue-violet band covers the region 

 from A 4050 to A 5000. The bands AA4600, 4770 and 4980 at 8° 

 have shifted slightly to the red with rise of temperature. 



None of the other bands seem to shift to the red at all and 

 the broadening seems to be quite symmetrical. The band at A 5500 

 has become about twice as wide as it was at the lower temperatures 

 and the two red bands have merged into one band running from 

 A 6350 to A 6800. Between 73° and 80° the absorption increases 

 very greatly. All short wave-lengths are absorbed up to A 5050. 

 The band in the green runs from A 5450 to A 5600 and the band in 

 the red has also widened very greatly, extending from A 6200 to 

 A 6800. 



{b) Copper Bromide {A and B, Plate VIII.). 



The two spectrograms showing the absorption spectra of copper 

 bromide in water for various temperatures were made for different 

 concentrations of the salt. A gives the absorption of a 2.06 normal 

 solution I mm. thick and B the absorption of a 0.25 normal solution 

 8 mm. thick. The time of exposure to the Nernst glower was 2 mins. 

 (current 0.8 amperes and slit width 0.20 mm.) and to the spark 

 6 mins. Starting with the strip nearest the comparison scale the 

 temperatures at which exposures were made for A were 6°, 17°, 

 30°, and 45° ; for B 6°, 17°, 31°, 46°, 59°, 71°, and 85°. 



As the spectrograms show, the effect of change of temperature 

 on the absorption spectrum is very marked. Above 45° the concen- 

 trated solution did not transmit enough light to affect the photo- 

 graphic film. 



