Arsenic in nitric acid

Baxter and Coffin,1 in 1909, also heated silver arsenate in hydrogen chloride. Samples of different origin were used, with slightly different results. They also dissolved the arsenate in nitric acid and precipitated the silver as chloride or bromide. The following mean values were obtained ... 

Ammonium molybdate, when added in considerable excess to a boiling solution of an arsenate in nitric acid, gives a yellow crystalline precipitate of ammonium 12-molybdo-arsenate, (NH4)3H4[As(Mo207)6]. 4H20 (see p. 215). Like the corresponding molybdo-phosphate, the precipitate is readily soluble in ammonia or aqueous alkali. The arsenate may be detected in the presence of phosphate by boiling the yellow precipitate with aqueous ammonium acetate until clear a white precipitate or turbidity on cooling shows the presence of arsenate, and the filtrate may be tested for phosphate.1... 

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