IOWA ACADEMY OF SCIENCES. 
13 
ADDRESS OF, THE RETIRING PRESIDENT. 
RECENT ADVANCES IN THE THEORY OP SOLUTIONS. 
BY LAUNCELOT W. ANDREWS. 
Ten years ago nothing was known of the molecular magni- 
tudes of substances which could not be converted into the gas- 
eous condition Concerning the constitution of the much greater 
number of compounds that exist only as solids or liquids, our 
ignorance was complete. 
Within the period named, a host of investigators, among 
whom the names of Raoult, Van’t Hoff, Nernst, Arrhenius, 
and Ostwald are the most distinguished, have devoted them- 
selves to studies of the liquid state, and their labors have 
poured a flood of light into the darkness. 
The researches of Raoult may be looked upon as forming the 
basis of the new movement. 
Any study of the liquid state must in the first instance con- 
cern itself with the phenomena which limit this state, namely, 
freezing on the one hand and boiling on the other. It had long 
been known that, in general, the presence of foreign matter in 
solution depresses the freezing point of a liquid, and raises its 
boiling point. Coppet had already paved the way for the 
quantitative study of the first of these phenomena which Raoult 
(1886-1888) carried on with great experimental skill and 
extended to the second. 
This investigator, unguided and unbiased by any theory, 
established the interesting and important fact that the depres- 
sion of the freezing point of a solvent resulting from the addi- 
tion of small quantities of a second substance is directly pro- 
portional to the number of molecules of the material added, 
being independent of the kind or weight of these molecules, 
and that the elevation of boiling point followed the same law. 
In other words: Urst, the depression of the freezing tempera- 
ture of a solvent is directly proportional to the amount, and 
