4-20 Prof. Graham on Watet' as a Constituent of Salts. 



Sulphate of Copper with Sulphate of Soda : CuS(NaS) + H^ 

 Sulphate of Copper and Soda, 

 Like the other double salts of sulphate of soda, this salt 

 cannot be formed directly, being decomposed by water. Even 

 when it is attempted to form it by double decomposition from 

 the bisulphate of soda, in general a large quantity of sulphate of 

 soda and of sulphate of copper are separately deposited before 

 the double salt appears. It is then deposited in a crust, con- 

 sisting of small but distinct crystals, which are slightly deli- 

 quescent, and appear to contain two proportions of water. 

 This salt is easily made anhydrous, and thereafter fuses at an 

 incipient red heat without loss of acid, and remains of a blue 

 colour when cool. The fused salt does not split into thin 

 scales in the progress of cooling, as the corresponding sul- 

 phate of copper and potash does. 



Sulphate of Manganese with Saline Water: MnSH + H*. Sul- 

 phate of Manganese, 

 The water in this salt was found to be reduced from five 

 atomic proportions to little more than one, by drying the cry- 

 stals in open air at 238°, while one entire atomic proportion 

 was retained at 410°. Flesh-coloured crystals, dried in vacuo 

 in warm summer weather, without artificial heat, lost some- 

 what more than three proportions of water. 



