2l8 REPORTS OX INVESTIGATIONS AND PROJECTS. 



The general effect of rise in temperature is to deepen the color of solutions 

 of inorganic salts. This is due to a widening of the absorption bands with 

 rise in temperature, up to the highest temperatures studied. It was found 

 for every pure salt dissolved in a single solvent that the absorption bands 

 widen with rise in temperature ; at the same time they become more diffuse 

 and the edges hazier. There is a very great increase in the absorption of all 

 solutions in the short wave-length region of the spectrum as the temperature 

 is raised. 



The effect of rise in temperature on the absorption spectra of neodymium 

 salts in mixtures of alcohol and water, where both the "water" and "alcohol" 

 bands appear simultaneously, was studied. With rise in temperature the 

 "water" bands w-ere more affected than the "alcohol" bands, showing that the 

 "hydrates" are less stable with rise in temperature than the "alcoholates." It 

 was also found that the acid aggregates formed by the action of acids on 

 neutral uranous salts are more stable with rise in temperature than the 

 neutral aggregates formed by the interaction of salt and solvent. 



A study of all the facts brought out in this work, which has now been in 

 progress for five years, has led to a theory of absorption spectra which seems 

 to account for the facts, and which we believe will prove helpful, at least as a 

 working suggestion. It is impossible in this brief report to discuss this 

 theory or the work of the year in any detail. The whole work is now in 

 press, and will soon be published by the Carnegie Institution of Washington 

 as Publication No. i6o. 



The problems in spectroscopy now under investigation in this laboratory 

 include the effect of ions as compared with molecules on the absorption 

 spectra of solutions; the effect of rise in temperature on the absorption 

 spectra of aqueous solutions ; and the measurement of the intensity of absorp- 

 tion lines and bands by means of the radio-micrometer and thermoelectric 

 junctions. 



Morse, H. N., Johns Hopkins University, Baltimore, Maryland. Grant No. 

 689. Measurement of the osmotic pressure of solutions. (For previous 

 reports see Year Books Nos. 2-9.) $1,800 



The work of the past year has been mainly a continuation of that of the 

 previous one. The object, as stated in the last report of progress, was to 

 determine with all possible exactness the relation of osmotic pressure to 

 temperature. Cane-sugar solutions, ranging in concentration from one-tenth 

 weight-normal to weight-normal, have now been investigated at intervals of 

 5° between 0° and 25°, and the temperature coefficient within this field has 

 been found to be identical with that of gases. The following tables present 

 the results obtained, each result being a mean of two or more closely agree- 

 ing values. The total number of experiments represented is 147. 



