EFFECT OF TEMPERATURE ON ABSORPTION SPECTRA. 75 



In most cases x, x', z, and z' would probably be small; y and y' may also 

 be small, and if hydrochloric acid or some other chloride is present, it might 

 be possible to have systems of the following composition: 



++ + t 



./-,; U0 2 }ar 2 {HorCa . . . }^{U0 2 Cl 2 }t/ 2 {HCl,CaCl 2 . . . }z{Cl}{CH 3 OH} 



+ 



+ + 



Zi'{Nd}s 2 '{H,Ca . . . Jy/JNdCL, }.(//{ HCl,CaCl 2 . . . ]v{Cl}a'{CH 3 OH} 



The absorption may be due to some condition, possibly one of internal 

 ionization of the aggregate, and as long as the number of aggregates remains 

 constant, Beer's law will hold. Free ions may split off from the aggregate 

 without the character of the absorption being greatly changed. It might be 

 that if the aggregates were completely broken up into their constituent ions 

 and molecules no characteristic absorption would be shown. 



In this case, a and a' n\&y either be considered as being constant, or as 

 being so large that the atmosphere of the solvate around the absorber is so 

 extensive that it is immaterial whether the outer solvent molecules are present 

 or not. On account of the fact that solvent bands coexist, and do not shift 

 into each other as the proportion of the solvents is changed, it will be assumed 

 that at least the inner and effective solvent molecules are all of one kind in 

 any "spectral" compound. 



As to the numerical value of the y's the absorption spectra of course do 

 not furnish evidence. The phenomena of the constancy of the wave-length 

 of the uranyl sulphate and uranyl nitrate bands, with great dilution of these 

 salts, leads to the conclusion that in this case at least the value of y is greater 

 than unity. Freezing-point, boiling-point, conductivity, and osmotic pressure 

 measurements should aid in determining the values of x, y, and z in the above 

 equations. 



The existence of complex aggregates of the above kind is quite rare in 

 inorganic chemistry, although cases have been known. Our own work on the 

 reduction and oxidization of certain uranium salt and acid aggregates has 

 shown that these different aggregates have very different chemical properties. 

 Some cases of a series of a similar set of compounds might be cited, e.g., the 

 cobaltamines. A large number of cobaltamines are known, and these have 

 been divided into six series. 



The diamine series [Co(NH 3 ) 2 ]X 4 M. In this series X = N0 2 and M is 

 one atomic proportion of a monovalent metal, or the equivalent quantity of 

 a divalent metal. These salts are prepared by the action of alkaline nitrites 

 on cobaltous salts in the presence of a large amount of ammonium chloride 

 or nitrate. The salts are yellow or brown crystalline solids, and are not very 

 soluble in water. 



The triamine series [Co(NH 3 ) 3 ]X 3 . X may be CI, NO.,, N0 2 , ^S0 4 , etc. 



The tetramine series, including, 



Praseo salts [R,Co(NH,) JX. X = CI. 

 Croceo salts [(N0 2 ),Co(NH 3 )JX. 

 Purpureo salts [RCo(NH 3 ) 4 ,H,0]X 2 . 

 Roseo salts [Co(NH 3 ) 4 (H,0),]X,. 

 Fuseo salts [Co(NH 3 )JOH. A\. 



