1892-93.] Prof. Tait on Com][>ressibility of Aqiieous Solutions. 141 
Preliminary Note on the Compressibility of Aqueous 
Solutions, in connection with Molecular Pressure. 
By Professor Tait. 
{Ahstmct.) 
(Read June 5, 1893.) 
The experiments referred to in my paper of March 6th {ante, 
p. 65) have been completed, but the results are by no means so 
exact as I hoped to make them. There was great difficulty in pro- 
curing the small bore tubes for the piezometers, and thus I had to 
employ them without previous calibration, as the solutions to be 
experimented on had already been prepared, and their densities 
determined at definite temperatures. Delay might have led to 
evaporation. When I proceeded to the calibration, after completing 
a large series of experiments, I was greatly annoyed to find that 
the bores of many of the tubes were by no means uniform. This 
accounts for the fact that my experiments, though fairly concordant, 
are not sufficiently so to afford more than a very strong probability 
in favour of the general result of the inquiry. For this reason I 
have described my paper as a Preliminary Note. 
The idea I sought to develop was of the following nature. I 
had found that the average compressibility of water, at any one 
temperature, could be well represented by the simple formula 
A 
B+i?’ 
where p is the range of pressure through which the compressibility 
is measured ; A and B being functions of temperature. But I also 
found that for aqueous solutions of common salt, of different 
strengths, and at the same temperature as the water, the formula 
was altered to 
A . 
B -t-s+2^ ^ 
where A and B were as before, and s was proportional to the weight 
of salt dissolved in 100 of water. In particular that, when 1 ton- 
