che;mistry — jonb;s. 193 



progress of the work and of the suggestive elements which have developed, 

 Pr. Otto Folin and Dr. Theobald Smith, both of the Harvard Medical 

 School, have consented to associate themselves with the future course of the 

 investigation. Dr. Charles G. Weld, of Boston, has also generously put the 

 investigation upon a satisfactory financial basis. 



Jones, Harry C, Johns Hopkins University, Baltimore, Maryland. Grant 

 No. 499. Investigation on the absorption spectra of solutions — a con- 

 tinuation of the work on hydration in aqueous solutions and solvation 

 in solutions in general. (For previous reports see Year Books Nos. 2, 

 3, 4, 5, and 6.) $800. 



This investigation on the absorption spectra of solutions, carried out with 

 the assistance of Dr. John A. Anderson, is an extension of the work of Jones 

 and Uhler on absorption spectra, published by the Carnegie Institution of 

 Washington as part of publication No. 60. 



A number of problems in connection with the absorption of light by dis- 

 solved substances were taken up in this work. The effect on absorption of 

 keeping constant the total amount of coloring matter in the path of the beam 

 of light, but varying the concentration of the solutions, aqueous and non- 

 aqueous, was pretty thoroughly studied. The effect of keeping constant the 

 total number of molecules in the path of the beam of light, and allowing the 

 number of the ions to vary was also carefully investigated. 



Such dehydrating agents as calcium chloride and aluminium chloride were 

 added to the aqueous solutions of colored chlorides, and the resulting absorp- 

 tion spectrum photographed. 



The addition of water to the solutions in non-aqueous solvents was care- 

 fully studied, and interesting results were obtained in this field. The salts 

 brought within the scope of this investigation are the chloride, bromide, 

 nitrate, sulphate, sulphocyanate, and acetate of cobalt ; the chloride, sulphate, 

 and acetate of nickel ; the chloride, bromide, and nitrate of copper ; the chlor- 

 ide of iron ; the chloride and nitrate of chromium ; the chloride, bromide, and 

 nitrate of neodymium ; the chloride and nitrate of praseodymium ; and the 

 chloride and nitrate of erbium. 



The method of making the spectrograms, and the cells employed for hold- 

 ing the solutions, were essentially the same as had been used by Jones and 

 Uhler. The electrodes for obtaining the spark were, however, quite differ- 

 ent. Instead of passing the spark between electrodes of zinc-cadmium, it 

 was found that much better results could be obtained by using carbon elec- 

 trodes which had been dipped into a solution of ammonium molybdate, 

 heated, then into a solution of uranium nitrate and again heated. 



The results obtained with the 1,200 solutions studied will soon appear as 

 publication No. no of the Carnegie Institution of Washington. A few of 

 the facts established and the conclusions reached can, however, be given here. 



