

PHYSICAL CONSTANTS OF SATURATED SOLUTIONS. 203 



The second table gives the results obtained with the apparatus shown in fig. 6. 



Columns I., II,, III., and IV. give the temperature of filling, the total pressure, 

 the density, and the solubility, respectively, when the temperature of the oil bath 

 was below the boiling-point, but close to and rising; while columns V., VI., VII., 

 and VIII. give the same, when the oil-bath temperature was higher than the boiling- 

 point, but close to and falling. 







TABLE II. 



Purity of the Salts the Chlorides. 



The alkali chlorides were obtained from Messrs. MKRCK, and were sold as the 

 purest they made ; the thallous chloride came from Messrs. KAIILBAUM, and was also 

 sold as pure. 



The solutions of the potassium and sodium salts did not require filtering, and were 

 tested for purity by an analysis of their chlorine contents. The sodium salt giving 

 60'58 per cent, (calculated 60'5'J per cent.) and the potassium 47'60 per cent. 

 (calculated 47 '54 per cent.). The rubidium chloride was tested spectroscopically for 

 the presence of potassium and caesium by first locating the chief lines of these metals 

 by observation of their spectra on the graduated circle of the spectroscope, and then 

 exploring the rubidium spectrum for them. No definite evidence of impurities was 

 obtained. An analysis of the chlorine content gave 29 '34 per cent, (calculated 

 29 '32 per cent.). From the appearance of the caesium chloride it was thought 

 necessary to filter the solution and recrystallise several times ; the mother liquor of 

 the first recrystallisation was distinctly yellow, that of the second faintly so, while 

 the third was colourless. A spectroscopic examination, similar to that mentioned 

 above for the rubidium salt, revealed, it was thought, a trace of rubidium. An 

 analysis of the chlorine content gave 21 '13 per cent, (calculated 21 '06 per cent.). 



The thallous chloride was found to be free from lead, and an analysis of the 

 thallium content gave 8 5 '40 per cent, (calculated 8 5 "21 per cent.). Owing to the 

 insoluble nature of this salt, the solubility determination cannot be relied on to as 

 great a degree of accuracy as in the other determinations. 



2 D 2 



