| Arsenic Trisulphatotrioxide, As2O3.3SO3, sometimes called arsenic sulphate, As2(SO4)3, is obtained by heating arsenious oxide with sulphur trioxide at 100° C. and maintaining the mixture at this temperature until excess of the latter oxide is expelled. It may also be separated from the mother liquor from the preparation of the tetra- sulphato-compound. The trisulphato-compound is less stable than the mono- and di-compounds described above. |