Gold Bromide (HAuBr4)
W-18 was obtained as a solid and has poor solubility for all the solvents tested in this study. Even when partial dissolution was achieved, no characteristic crystal formation was observed for any of the reagents. With the gold bromide reagent upon standing, yellow feathery branches were observed. These structures are very faintly visible in crossed polars. This test cannot be used reliably for W-18.