SPECTROPHOTOGRAPHY OF CHEMICAL REACTIONS. 67 



absorption due to a solution of uranous bromide in 3.5 parts water and 6 parts 

 methyl alcohol. To this is added a solution of potassium nitrate in 2 parts 

 water and 3 parts methyl alcohol, which results in a precipitate. The precipi- 

 tate was filtered off and the resultant solution gives the absorption as repre- 

 sented in strips 2 and 3. It will be seen that only the uranous hydrate has 

 been precipitated. Strip 4 represents another solution of uranous bromide in 

 3.5 parts of water and 6 parts of methyl alcohol, and to this solution is added 

 calcium nitrate dissolved in 2 parts of water and 3 parts of methyl alcohol. 

 The effect of the addition of this calcium nitrate is to cause the almost com- 

 plete disappearance of the water bands, while the intensity of the alcohol 

 bands remains practically the same. In the fifth strip it will be seen that the 

 long wave-length water band is nearly 150 Angstrom units in width, and is 

 very much wider than the other red water band. This spectrogram furnishes 

 striking evidence in support of the view of the selective oxidization of the 

 uranous hydrate in this solution. 



A, plate 42, represents the absorption of uranous bromide in water and 

 methyl alcohol to which an aqueous solution of calcium nitrate is added. The 

 spectrogram shows the decrease in the intensity of the alcohol bands. This 

 is most likely due to the increase in the percentage of water present in the 

 solution. The second strip shows the very quick change in the relative inten- 

 sity of the two red uranous water bands. This effect seems to be a general 

 one for the addition of calcium nitrate to solutions of uranous chloride, bro- 

 mide, or sulphate. The spectrogram does not seem to indicate that any of 

 the uranous salt has been oxidized. 



B, plate 41, shows that when hydrogen peroxide is dissolved in the same 

 proportion of water and methyl alcohol as the uranous bromide, the alcohol 

 and water bands both disappear at the same rate, indicating that hydrogen 

 peroxide has no selective action on these two solvates. 



The solution of uranous chloride used was acidulated with hydrochloric 

 acid, and when mixed with an equal volume of methyl alcohol gave the water 

 and methyl alcohol bands of about the same intensity. Two solutions were 

 used: one (spectrogram A, plate 36) in which the alcohol bands were much the 

 stronger, and the other (spectrogram A, plate 41) in which the water bands 

 were slightly stronger. Calcium nitrate in 2 parts of water and 3 parts 

 alcohol was added, the amounts being 10, 20, 40, and about 120 drops. The 

 last strip of A, plate 41, represents the result of the addition of hydrogen 

 peroxide. Spectrogram A, plate 38, represents the effect produced by add- 

 ing sodium chlorate dissolved in equal parts of water and alcohol. In this 

 case no oxidization resulted. A, plate 36, shows very little change in either 

 the water or the alcohol bands. The red water bands have their relative 

 intensity greatly changed, however, on the addition of calcium nitrate. A, 

 plate 41, shows this same relative change in the intensity of the two red water 

 bands. The spectrogram shows a very considerable increase in the intensity 

 of the alcohol bands, and a decrease in the intensity of the water bands. A, 

 plate 38, shows very little if any change at all in the absorption spectra. Even 

 the red water bands remain of about the same relative intensity. 



B, plate 38, represents the absorption of one part of uranous chloride in 

 water to which one part of methyl alcohol is added. Succeeding strips, with 



