10 MR J. Y. BUCHANAN ON THE 



PAR. PAGE 



94. The specific gravities of the solutions were adju'^ted to the value which they would have if 174 



their gram-molecules had the uniform weight 121, which is the actual molecular weight 

 of tlie heaviest of the three, namely, rubidium chloride. This adjustment of the 

 molecular weights does not materially affect the relations of the solutions as regards 

 their specific gravities. The displacements of these solutions are compared. 



95. The differences of displacement are discussed. 175 



96. The displacement of solutions of the artificial isomer (K ) is considered in reference 176 



to the displacement of solutions of the constituent salts. 



97. Comparison of displacement of solutions of the artificial isomer as obtained by experiment 177 



and as calculated. 



SECTION XIV. 



The Specific Gravity and the Displacement of Solutions of the Chlorides of 

 Beryllium, Magnesium and Calcium. 



98. Preparations of weak solutions — m = 1/2 to 1/1024 — of each of the three salts, and of strong 178 



solutions of MgCl2 and CaCla for 7n = 1 up to supersaturation. The solutions saturated 

 with MgClj and CaClj at 195° C. contain 5'918 and 6'613 gram-molecules respectively 

 in 1000 grams of water. A supersaturated solution of magnesium chloride contained 

 5 982 MgClg in 1000 grams of water. This solution was formed with moderate absorp- 

 tion of heat and crystallised very readily. The supersaturated solution of calcium 

 chloride contained 7 '225 CaClj per 1000 grams of water. This solution was formed 

 with great absorption of heat, and offered considerable resistance to crystallisation. It 

 was found that when the quantities of the crystallised salt MgCl26H20 and water used 

 were such as to produce a solution containing about 2 MgClj per 1000 grams of water, 

 there was an appreciable liberation of heat. When further salt was dissolved this gave 

 place to absorption of heat, and, at saturation, the temperature of the solution was lower 

 than the initial temperature of the water used. 



99. Table giving the results of specific gravity determinations made upon solutions of 179 



the chlorides of beryllium, magnesium and calcium of different concentrations at 

 19-5° C. 



100. While the bases BeO, MgO and CaO give an alkaline reaction with litmus paper, the 180 



chlorides of magnesium and calcium are neutral, while that of beryllium is acid. The 

 beryllium chloride solution was made from the sulphate by double decomposition with 

 barium cliloride. The more dilute solutions were prepared by diluting the more con- 

 centrated ones. The specific gravities of the strong solutions were made with open 

 hydrometers A and B, and those of the weak solutions with closed hydrometers Nos. 3 

 and 17. Comparison of (S - 1) with m. A table is given from which it is apparent that 

 the values of (S - 1) produced by dissolving 1/2 MR in 1000 grams of water are exactly 

 proportional to the molecular weights of the salts in the case of MgClj and CaClj, 

 and that this proportionality is maintained for values of m = l/16 and 1/128. In 

 the case of beryllium chloride the proportionality fails. The specific gravities of 

 the solutions of beryllium chloride for which m = 1/512 and to= 1/1024 fall below 

 unity, from which it follows that the displacement of these two solutions must be 

 greater than the sum of the displacements of the salt and water which they 

 respectively contain. The values of dS for solutions of CaClj which are near 

 saturation are discussed. 



