This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Arseniate of sodium should be kept in well-stopped vials. Colorless, transparent, prismatic crystals, slightly efflorescent in dry air, odorless, having a mild, feebly alkaline taste, and a faintly alkaline reaction. Soluble in 4 parts of water, and very slightly soluble in alcohol at 15° C. (59° F.); very soluble in boiling water, and soluble in 60 parts of boiling alcohol. Arseniate of sodium is very seldom required and usually not put in the apparatus, but in the required amount gauged into every bottle. As but trifling quantities are necessary in the artificial combination of mineral waters, a one per cent, solution (one part dissolved in 99 parts of distilled water) is convenient, and the required small quantities are better measurable. Proportion 100 to 1.