1898.] of Copper and Sodium. 247 



dilute alcohol instead of with water until free from sodium acetate and 

 finished as before. It appears as probable that the acetic acid plays 

 the same part in this case as alcohol does in Vortmann's salts. The 

 white or faintly yellowish white salt turns yellow in contact with water 

 especially if the salt be previously dried. On comparison of the result 

 of analysis of the different preparations as given in the annexed table 

 we find that this salt again is a double thiosulphate of copper and 

 sodium having the formula Cu 2 S 2 O s Na 2 S 2 3 2J H 2 0. Russel describes 

 (Ch. Ztg. 9233) a salt Cu 2 S 2 3 Na s S 2 3 H 2 whose properties and 

 method of preparation are altogether different from the one described 

 here. This salt when once perfectly dry, also keeps well even in con- 

 tact with the atmosphere. 



