252 REPORTS ON INVESTIGATIONS AND PROJECTS. 



The measurement of osmotic pressure at high temperatures is beset with 

 many serious difificulties. The most important of these are due: (a) to the 

 great difference between the temperature of the air and the temperature at 

 which the solutions must be maintained; (b) to the difference in the expan- 

 sion coefficients of the diverse materials which are employed in the con- 

 struction of the cell; (c) to the deleterious effect of long-continued heating 

 upon rubber; and (d) to the fact that, under the same conditions of tem- 

 perature, all apparatus made of glass becomes exceedingly brittle and liable 

 to destruction. 



During the past year the writer has had associated with him, in the work 

 carried on under the auspices of the Carnegie Institution of Washington, 

 Doctors W. W. Holland and J. C. W. Frazer. Dr. Holland has been engaged 

 upon the investigation continuously for several years, and its successful 

 prosecution is due in a large measure to the skill and experience which he 

 has acquired. Dr. Frazer was associated with the work for several years 

 during its earlier stages, and contributed much to the success with which the 

 greatest obstacles to the measurement of osmotic pressure were finally over- 

 come. He has resumed the work after an absence of four years. Since his 

 return, the investigation of the osmotic pressure of the electrolytes has been 

 given more attention than was possible in the past, and much has been 

 learned that is interesting, and probably important. However, some serious 

 difficulties remain to be overcome before the osmotic pressure of electrolytes 

 can be ascertained with the same ease and certainty as that of the non- 

 electrolytes. So far as the observations made to date can be interpreted, it 

 appears probable that the principal obstacle in the way of measuring the 

 osmotic pressure of electrolytes is due to the effect of that class of bodies 

 on the colloidal character of the membrane. 



In less important capacities, and as volunteers, Messrs. F. S. Dengler, 

 L. Van Doren, H. O. Eyssell, and J. B. Zinn have aided in the work of the 

 past year. Mr. Van Doren has investigated the relative merits of certain 

 semi-permeable membranes. Messrs. Dengler and Eyssell have studied the 

 problems of the detection and determination of minute quantities of certain 

 poly-acid alcohols whose osmotic pressure it is intended to investigate in the 

 near future. Mr. Zinn has aided in the measurement of the pressures which 

 appear in the tables given in this report. 



Noyes, Arthur A., Massachusetts Institute of Technology, Boston, Massa- 

 chusetts. Grant No. 763, allotted December 15, 191 1. Researches upon 

 the properties of solutions in relation to the ionic theory. (For previous 

 reports see Year Books Nos. 2-10.) $3,ooo 



The work of the past year may be outlined as follows : 

 A series of seven articles has been published describing the researches 

 carried out during the last few years on the effect of salts on the solubility 

 of other salts. The more important results of the investigations were sum- 

 marized in last year's report. 



