CHAPTER V. 



NICKEL SALTS. 



Introduction. Nickel chloride. Nickel sulphate. Nickel acetate. Conductivity data. 



INTRODUCTION. 



Among the more recent investigations on nickel salts may be mentioned 

 those of Miiller 1 and Jones and Anderson 2 . Miiller found that Beer's law 

 holds for solutions of nickel nitrate and sulphate, but that the chloride and 

 bromide showed variations from the law. He concludes that both hydra- 

 tion and aggregation play a part in producing these variations from Beer's 

 law. 



Jones and Anderson 2 find that Beer's law holds for the chloride, 

 sulphate and approximately for the acetate. Rather narrow bands were 

 found at U 6110, 6250, and 6440 for a mixture of nickel and aluminium 

 chlorides. This is another example of the effect of the presence of alumin- 

 ium or calcium chloride. Further work should be done on the effect of 

 the presence of these salts and of free hydrochloric acid. The investiga- 

 tions should be carried out at low temperatures. 



Nickel Chloride. 



A spectrogram showing the effect of rise in temperature was made for 

 an aqueous solution of nickel chloride, 2.66 normal concentration and 3 mm. 

 length of layer. The length of exposure to the Nernst glower was 2 minutes, 

 current 0.8 ampere and slit-width 0.20 mm. The exposure to the spark 

 was for 5 minutes. Starting with the strip next the numbered scale, the 

 temperatures are 2, 14, 29, 44, 58, 70, and 84 C. 



The absorption of nickel chloride consists of a band which absorbs 

 the ultra-violet, violet, and blue portions of the spectrum. At the low 

 temperatures there is a small transmission in the blue, but at 2 practically 

 all light is absorbed up to X 4200. As the temperature is raised the absorp- 

 tion extends towards the region of greater wave-lengths; at 44 it is at X 4400 

 and at 84 at X 4600. The transmission extends into the red as far as the 

 films are sensitive. 



A spectrogram (Plate 21, B) was made of an aqueous solution of a 2.66 

 normal concentration of nickel chloride of 2 mm. depth of layer. The 

 length of exposure to the Nernst glower was 2 minutes and to the spark 

 6 minutes. The current through the Nernst glower was 0.8 ampere and 

 the slit-width 0.20 mm. Starting with the strip adjacent to the numbered 

 scale, the temperatures of exposure were 5, 18, 30, 44, 57, 75, and 85. 



At the lower temperatures there is complete absorption of almost all 

 the shorter wave-lengths up to ^4250 at 5. There is an exception not 

 shown in the printed spectrogram, and this is a very faint transmission 



1 Ann. Phys., 12, 767 (1903) ; 21, 515 (1906). 



3 The Absorption Spectra of Solutions, Carnegie Institution of Washington Pub. No. 110. 



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