Complex salts of Sulphato-compounds of Arsenic

Complex salts containing arsenic tri- or pent-oxide and sulphurtrioxide, apparently in a complex anion, have been described. The following are examples:

2K2O.As2O3.4SO3	Prepared by heating solutions of the metallic sulphate and arsenious oxide in concentrated sulphuric acid.
CaO.As2O3.3SO3
PbO.As2O3.2SO3
2K2O.As2O5.2SO3.3H2O	Obtained from solutions of the alkali dihydrogen orthoarsenate in sulphuric acid.
2(NH4)2O.As2O5.2SO3.3H2O
2Na20.As2O5.2SO3.3H2O
3Ag2O.As2O5.SO3	Obtained by dissolving silver orthoarsenate in sulphuric acid