CONCENTEATION OF SALT SOLUTIONS. 



27 



These experiments are hardly sufficient for our purpose. Nevertheless they seem to 

 show that in the case of this salt the formula holds up to a concentration of about 3 per 

 cent. 



An'MiNiUM Sulphate. — Al,(SO.|);,. 

 Observer: Hassenfratz. ' 

 Temperature: 12° '50. 

 Formula: D,2.5 = 0-99949 + 0-0092083 p. 



These results show the formula to hold up to a concentration of 25 per cent. 

 According to Eeuss, ^ as reported in the ' Beiblatter z\\ den Annalen der Physik und 

 Chemie,' ' the density of Aluminium Sulphate solutions for concentrations ranging from 1 

 to 25 per cent, of salt (whether anhydrous or crystallised is not stated) in solution, may 

 be represented by the formula : — 



D,5=l-00*7+001jo. 



Now we know that for p^O, Di3= 099915. Hence either this formula is inadequate 

 or the law of the variation of density with concentration is very different for solutions 

 containing between and 1 per cent, of salt from what it is for solutions containing be- 

 tween 1 and 25 per cent. Possibly the curve showing the relation between density and 

 concentration is so slightly curved that the densities of solutions within the given limits 

 of concentration may be expressed by the above formula to three places of decimals. 



Potash Alum. — A1K(S04)2. 



Obaerrer : The author. 



Temperature : 20°C. 



Formula : D,,„ = - 99827 + - 0095187 p. 



' Ann. de Chim. xxviii (1799) p. 296. 

 ' Bd. ix (1885) p. 309. 



- Chem. Ber. xvii (1884) p. 2888. 



