1903-4.] Thermal Expansion of Solutions of Hydroxides. 281 
On the Thermal Expansion of Dilute Solutions of certain 
Hydroxides. By George A. Carse, M.A., B.Sc. 
Communicated by Professor MacGregor. 
(Read March 21, 1904. ) 
In a paper communicated to the Nova Scotian Institute of 
Natural Science,* Professor MacGregor has shown that in the case 
of weak aqueous solutions of certain hydroxides, the volume of a 
solution is less than the volume of water used in its preparation. 
At his suggestion I have investigated the hydroxides of sodium, 
barium, and strontium, to ascertain whether they exhibit this pro- 
perty, and how the excess of the volume of solution over the 
volume of constituent water varies with the temperature. From the 
observations made, I have also determined the thermal expansion 
coefficients, and found how they vary with temperature and with 
concentration. 
Preparation and Determination of Composition of Solutions. 
The substances were purchased as chemically pure from E. 
Merck, Darmstadt, and were found to he of sufficient purity, the 
sodium hydrate being tested for carbonate, chloride, and sulphate, 
and the barium and strontium hydrates for strontium and calcium, 
barium and calcium, respectively. 
The original solutions were prepared by dissolving the substances 
in twice-distilled water, and they were analysed volumetrically by 
titration with acid, plienolphthaleiu or methyl orange being used 
as an indicator. The concentration of the acid had been 
determined by means of sodium carbonate made by heating sodium 
bicarbonate. The value of the chemical composition of any 
solution thus analysed was got by taking the mean of several 
determinations. The values of the atomic weights used were those 
given by the International Atomic Weight Table of 1904, and the 
* Trans. Nov. Scot. Inst. Nat. Sc., 7, 368, 1889-90. 
