28 



MACGEEGOE ON DENSITY AND 



According to these experiments the above formula holds up to a concentration of at 

 least 1"7 per cent. 



The following observations weve made by Gerlach ' on soltitious of this salt at 

 IT^.SC. The calculated densities are obtained from the formula : — 



D„. 



0-998'75 + 0.00939*7 /J. 



The comparatively small difference between the observed and calculated density for 

 a solution containing 4"36 per cent, of anhydrous salt, makes it probable that the simple 

 proportionality of excess of density of solution over density of water, to concentration, 

 holds up to a concentration of about 2'5 per cent. 



Observer ; Hassenfvatz. - 



Temperature: 12°.5C- 



Formula : D,,.5 = ■ 99949 + ■ 008595 p. 



PoTASSir.M Sulphate. — K^SOj- 



The following is another series of observations of solutions of the same salt : — 



Observer : Gerlach. ' 



Temperature: 15°C. 



Formula: D,5 = 0-99915 + 0.00816 p. 



• Beiblatter Ann. Phys. Chem., xi (1887) p. 217. -' Ann. de Chim. xxviii (1799) p. 296. 



' Gerlach's Specifische Gewichte der gebraurhliohsten Salzlosungen, Freiberg, 1859 ; and Jahresberidit u. Fort- 

 echritte d. Chem., 1859). 



