| Strontium Orthothioarsenate, Sr3(AsS4)2.nH2O, may be prepared by digesting strontium sulphide with an aqueous solution of strontium pyrothioarsenate and, after filtering, either adding alcohol or evaporating to crystallisation. Strontium pyrothioarsenate, Sr2As2S7.nH2O, is obtained by mixing aqueous solutions of a strontium salt and sodium pyrothioarsenate, and evaporating the liquid. Both salts resemble the analogous calcium salts in properties. A crystalline double salt containing orthothioarsenate and pyrothioarsenite, and of composition Sr3(AsS4)2.Sr2As2S5.8H2O, has been obtained by evaporating in vacuo a saturated solution of arsenic pentasulphide in aqueous strontium hydrosulphide. |