1903-4.] Thermal Expansion of Solutions of Hydroxides. 291 
the concentrations and expansion coefficients are plotted on scales 
20 and 2 times those of the first set respectively. 
In the case of sodium hydroxide the expansion coefficient 
increases with concentration, and does so at a less rapid rate as the 
temperature rises. 
The strontium and barium curves seem to indicate that the rate 
of variation of expansion coefficient with concentration reaches 
Fig. 4. 
stationary values in the range considered, but no great stress can 
be laid on this conclusion, because of the uncertainty caused by the 
large errors in the expansion coefficient. 
The above experiments were carried out in the Natural Philos- 
ophy Laboratory, University of Edinburgh. I have to tender my 
best thanks to Professor MacGregor for the assistance he has 
afforded me in this work, both by way of suggestions and advice. 
{Issued separately August 15, 1904.) 
