240 EDWARD DIVERS AND TAMEMASA HAGA ; 



particles. The potassium hydroxide being in moderate excess, the 

 mother-liquor is bright yellow, like a solution of gold chloride. Both 

 precipitate and solution are changed by much water ; they become 

 brown, and the precipitate dissolves. Either .solution gives a brown 

 precipitate when heated, or when mixed with excess of potassium 

 hydroxide, or silver nitrate, or potassium amidosulphonate, and this 

 precipitate cannot be redissolved. The yellow solution is also unstable, 

 gelatinising on long standing, and leaving a colourless solution. Yellow 

 and brown precipitates and solutions appear all to be colloidal in 

 character. The brown substance in solution and the brown precipi- 

 tate are apparently silver oxide essentially. The yellow compound 

 is not blackened by light, is soluble without colour in potassium 

 amidosulphonate, and is slowly converted to a whitish, pulverulent 

 precipitate by digestion with silver-nitrate solution, and into a 

 white flocculent precipitate by excess of potassium hydroxide. Its 

 solution in a minimum of potassium amidosulphonate silvers glass 

 at a boiling heat. So does a solution of potassium amidosulphonate, 

 silver nitrate, and potassium hydroxide. As already stated, sulphite 

 appears to be produced in this reduction of silver. 



À solution of silver amidosulphonate does not sensibly dissolve 

 silver oxide. Silver nitrate behaves in solution with its equivalent of 

 potassium amidosulphonate like silver amidosulphonate towards potas- 

 sium hydroxide. If the silver nitrate is present in excess, and the 

 solution not too dilute, precipitation of the amidosulphonic compound 

 precedes that of silver oxide. If the proportion of potassium amidosul- 

 phonate is as two mol. to one of the silver nitrate, potassium hydroxide 

 causes no precipitate in solutions of moderate concentration ; that is to 

 say, amidosulphonic acid prevents the precipitation of silver oxide by 

 alkalis. A solution of 2 mol. potassium amidosulphonate, 2 mol. 

 potassium hydroxide, and 1 mol. silver nitrate dries up in the desic- 



