504 DIVEES AND HAGA : DEC03IP0SITI0N OF 



solution mixed with rancli barium sulphate, it was not easy to 

 titrate acid with lacmoid pajoer as indicator. The separation of 

 sulphate and amidosulphate is not a simple process, especially 

 when much sulphate is present derived from sources other than 

 the reaction to be dealt with. 



The salt employed in the experiments was either copper 

 hydroxyamidosalphate, or sodium hydroxyamidosulphate with 

 copper sulphate, or one of the alkali hydroximidosulphates with 

 copper sulphate. 



1. A solution of the copper salt, containing onl}^ a very 

 little copper sulphate was prepared from normal barium hydroxy- 

 amidosulphate and copj^er sulphate, the barium salt (this Journ., 

 3, 213, 216) liad to be prepared as wanted, because of the 

 instability of the hydroxyamidosulphates. The strength of the 

 solution was determined by a barium estimation (hydrolysis in 

 sealed tube and weighing of the barium sulphate). Copper sul- 

 phate in slight excess and carefully weighed was added to the 

 weighed solution of the barium salt, and the copper hydroxy- 

 amidosulphate at once used without filtering off the barium 

 sulphate. 



2. Sodium hydroxyamidosulphate solution was prepared just 

 before use by hydrolysing a centigram-molecule of the hydrox- 

 imidosulphate by adding to its solution a minute and known 

 quantity of sulphuric acid (this Journ., il, o) and to it was 

 added after neutralisation with sodium hydroxide half a centigram- 

 molecule of copper sulphate. 



3. Potassium or sodium hydroximidosulphate in the quantity 

 of a centigram-molecule was dissolved and directly heated with 

 a half molecule in centigrams of copper sulphate. 



The solution (either 1, 2, or 3) being in a small flask 



