2l6 REPORTS ON INVESTIGATIONS AND PROJECTS. 



neodymium salts are treated with nitric acid ; the salts and acids studied hav- 

 ing been selected so as to show the greatest spectroscopic changes when one 

 salt is transformed into another. 



Since these reactions do not differ chemically from reactions in general, 

 it is a fair question to ask at least ivhether chemical reactions in general are 

 not more complex than are represented by our ordinary equations? It is diffi- 

 cult, not to say impossible, to see why these intermediate systems should be 

 formed in the reactions studied spectroscopically if they are not also formed 

 in other chemical reactions. This suggestion seems all the more probable 

 in that there are certain lines of evidence, from the chemical side, pointing 

 to the existence of intermediate compounds in chemical reactions. 



In studying the third problem — the effect of temperature on the absorp- 

 tion of light by solution — a thick-walled steel tube closed at both ends with 

 glass or quartz plates and lined on the inside with gold was employed. Tubes 

 of different lengths were used for solutions of different concentrations. Con- 

 siderable difficulty has been experienced in closing the apparatus to withstand 

 high pressure, yet it has been possible to work with alcoholic solutions and 

 with mixtures of alcohol and water at temperatures well above the boiling- 

 point of alcohol. 



Although work on this problem can be said to be only fairly begun, some 

 results of interest have already been obtained. The effect of rise in tempera- 

 ture is, in general, to cause the absorption bands to widen, a few exceptions, 

 however, having been found. 



Solutions that show both the water-bands and alcohol-bands with equal 

 intensity at ordinary temperatures show these bands to have very unequal 

 intensities when the temperature is raised. Of the solutions studied the 

 alcohol-bands are the more persistent at the elevated temperatures, indicat- 

 ing that the alcoholates undergo less change in composition with rise in tem- 

 perature than the hydrates. 



The effect of temperature on the absorption spectra of solutions will be 

 extended next year to as high temperatures as may prove to be possible. 



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

 614. Study of the measurement of the osmotic pressure of solutions. 

 (For previous reports see Year Books Nos. 2-8.) $1,800 



The purpose of the work of the past year, as of that of the previous year, 

 has been to determine with all possible certainty the relation of osmotic 

 pressure to temperature. As the method of measurement has been improved 

 from time to time, and as the results which should agree have become more 

 concordant in consequence of the removal of known sources of error, it has 

 been found that the ratios of osmotic to calculated gas pressure at different 

 low temperatures has approached a constant value for any given concentra- 

 tion of cane-sugar solution. In other words, the later results indicated an 

 increasingly closer agreement between the temperature coefficients of osmotic 

 and gas pressure, i. e., that osmotic pressure obeys the law of Gay-Lussac 

 for gases. 



