This part of ISO 21587 specifies reagents, dissolution and gravimetric silica analysis for the chemical analysis of aluminosilicate refractory products and raw materials. This part of ISO 21587 gives alternatives to the X-ray fluorescence (XRF) method given in ISO 12677:2003, Chemical analysis of refractory products by XRF — Fused cast bead method. This part of ISO 21587 should be used in conjunction with ISO 21587-2 and ISO 21587-3, which give the analytical procedures for the determination of the following: — silicon(IV) oxide (SiO2) — aluminium oxide (Al2O3) — iron(III) oxide (total iron oxide calculated as Fe2O3) — titanium(IV) oxide (TiO2) — manganese(II) oxide (MnO) — calcium oxide (CaO) — magnesium oxide (MgO) — sodium oxide (Na2O) — potassium oxide (K2O) — chromium(III) oxide (Cr2O3) — zirconium oxide (ZrO2) — phosphorous(V) oxide (P2O5)