520 
Proceedings of the Royal Society of Edinburgh. [Sess. 
tartaric acid, and magnesium chloride hexahydrate as being solids which 
give expansion on solution. 
On the other hand, Carse * found that in the case of dilute solutions of 
certain hydroxides the volume of solution was less than the volume of 
water it contained. 
The curves in fig. 3 show the connection between the expansion on 
solution and the concentration at the two temperatures 0° C. and 25° C. 
At 0° C. a solution whose concentration is about 18*5 per cent, has the 
maximum expansion. At 25° C. a 26 per cent, solution evidently has 
maximum expansion. It will also be observed that the expansion increases 
considerably as the temperature is raised. 
Similar results were calculated for the temperatures 35° C. and 56° C., 
but, owing to no allowance being made for the expansion of the solid, their 
accuracy could not be guaranteed, hence they have been omitted. 
Chemistry Department, 
University of Edinburgh. 
* Proc. Roy. Soc. Edin., xxv. p. 286 (1904). 
( Issued separately September 7, 1910.) 
