62 1.8.C. Proceedings of the Ninth [N.S., XVIII, 
instead of attacking the readily oxidisable unacted sodium 
sulphite attacks the much more difficultly oxidisable sodium 
difficulty. In this case we shall have to assume that this 
peroxide instead of attacking the readily oxidisable unattacked 
sodium sulphite will attack the less readily oxidisable sodium 
arsenite by preference. It seems, therefore that the only 
course left to us is to find out the explanation in view of the 
formation of a complex of sulphite and arsenite or of sulphite 
and oxalate, and that this complex is oxidised as a whole. It 
is well known that complex oxalates and sulphites do exist. 
It has been observed ina previous paper (Dhar, Proc. Akad. 
Vetensk. Amsterdam, 23, 299, 1920) that in 
Intermediate the oxidation of sulphite and sulphurous acid 
compound forma- the sulphite ion is the active agent. On the 
addition of an arsenite to a sulphite, a com- 
plex which itself is oxidised as a whole is 
formed. At the same time the velocity of 
of an intermediate complex compound. 
The phenomenon of induced precipitation is of common 
occurrence. When any one of the phos- 
hates of iron, aluminium or chromium is 
. precipitated by sodium phosphate in pre- 
sence of acetic acid and calcium chloride the precipitate after 
being thoroughly washed with acetic acid gives test for calcium 
nduce 
precipitation. 
hydroxide in presence of copper sulphate, zinc sulphate, nickel 
the precipitates even after being 
precipitate after being thoroughly washed with ammonium 
chloride shows the presence of magnesium. 


