348 CARNEGIE INSTITUTION OF WASHINGTON. 



influence exerted by such factors as the formation of complexes in the 

 solutions, the difference in the viscosity of the various solvent-solutions 

 and the solutions in them, the change in the migration velocities of 

 the anions, and the effect of the various added salts on the dielectric 

 constants of the solvent-solutions. 



Dr. Connolly, working on another phase of the same subject, has 

 studied the different chemical activity of free and semi-combined 

 water as illustrated by the effect on the hydrolysis of acetic anhydride. 



The physical difference, already referred to, having been established 

 by Jones and certain of his co-workers, the chemical difference was 

 then investigated by Holmes and Jones. Their work indicated the 

 possibiUty of such a difference, although the inherent errors of their 

 method, due to the slowness of the reaction chosen and the effect of 

 outside catalyzers, made it difficult to obtain reliable results. Conse- 

 quently, a more rapid reaction was sought for — that of the hydrol- 

 ysis of acetic anhydride being finally adopted. The results obtained 

 apparently corroborate the deductions from the earlier work, although 

 here again its preliminary nature makes further investigation advis- 

 able before drawing any definite conclusions. The hydrated salts 

 studied, with the exception of magnesium chloride, all give results 

 for the decomposition of the acetic anhydride greater than those 

 of the non-hydrated ones, the latter all having a more marked hinder- 

 ing effect on the hydrolysis. In dilute solutions there is an appre- 

 ciable acceleration of the hydrolysis of the acetic anhydride over 

 that due to pure water alone. Sodium sulphate was found to have 

 this effect at all dilutions. The effect of rise in temperature was 

 also studied and found to increase the velocity of the reaction. In 

 contrast to the other hydrated salts, magnesium chloride was found 

 to act as do the non-hydrated salts, having a retarding effect on the 

 hydrolysis of acetic anhydride at all dilutions. 



Morse, H. N., Johns Hopkins University, Baltimore, Maryland. Measure- 

 ment of the osmotic pressure of solutions. (For previous reports see 

 Year Books Nos. 2-14.) 



Dr. Holland, assisted by Messrs. Blocher and Minter, has been 

 engaged, during a considerable portion of the past year, in experi- 

 mental work on the manufacture and recovery of the porous cells 

 used in the measurement of osmotic pressure. It has been empha- 

 sized in previous reports: (1) that the membrane must consist exclu- 

 sively of minute "plugs" of the active material which are driven 

 firmly into the mouths of the pores which open upon the interior wall 

 of the cell, or, if high pressures are to be measured, into the mouths 

 of the pores which open upon the exterior wall of the cell; (2) that 

 this essential condition makes necessary: (a) absolute uniformity in 

 the size of the pores, and (6) a degree of fineness of texture (magnitude 



