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CARNEGIE INSTITUTION OF WASHINGTON. 



Mr. Hawkins also determined the densities of several of the salts 

 employed in the foregoing investigations in order that vacuum correc- 

 tions might be applied. 



Mr. Charles Wadsworth, 3d, determined the changes in volume which 

 takes place during the solution of several alkali halides in ethyl alcohol 

 and pyridin at temperatures from 0° to 50° and at widely varying con- 

 centrations, and in water at 75° and 95°. Mr. A. B. Haw investigated 

 mercuric chloride in the same way. Both researches supplement earlier 

 work on the subject in this laboratory and the results do not conflict 

 with the hypothesis proposed as to the causes of the observed effects. 



Mr. J. E. Lansing eliminated several sources of error in the ''air- 

 current" method for determining the aqueous pressure of hydrated 

 salts, and obtained concordant results for several substances at several 

 temperatures. 



Detailed accounts of the foregoing researches are being prepared for 

 publication and will soon appear in various scientific periodicals. 



Jones, Harry C, Johns Hopkins University, Baltimore, Maryland. Con- 

 struction of a diffraction grating as an aid in the prosecution of researches 

 under the auspices of the Institution; also, Continuation of investigations on 

 the absorption spectra of solutions and on the conductivity and dissociation 

 of electrolytes in water and in non-aqueous solvents at different temperatures. 

 (For previous reports see Year Books Nos. 2-12.) 



The work on the absorption spectra of solutions, which has been in 

 progress continually in the laboratories of the Johns Hopkins Univer- 

 sity for the past eight years, under grants from the Carnegie Institution 

 of Washington, has been continued by Dr. Shaeffer and Mr. Paulus. 

 The results of this investigation and of others referred to below will soon 

 appear as Publication No.210of the Carnegie Institution of Washington. 



It was found last year, by Drs. Guy and Shaeffer, that solutions of 

 non-hydrated, non-absorbing salts are about as transparent as pure 

 water equal in depth to the water in the solution in question. This is 

 what would be expected. On the other hand, it was found that solu- 

 tions of strongly hydrated salts are more transparent than pure water 

 equal in depth to the water in such solutions. This observation was 

 regarded as important in its bearing on the solvate theory of solution. 

 Combined water had less power to absorb light than free water. 



