Arseniate of Soda. 2 NaO, HO, AsO5 + 14 HO or 24 HO.
Med. Prop. and Action. The same as those of Arsenious Acid, or Liq. Arsenicalis, but less irritating. Arseniate of Soda has been long used on the Continent, and a solution of it has been known and prescribed in this country under the name of Pearson's Solution, a preparation containing one grain of the Arseniate to ten fluid drachms of Water. Dr. Garrod observes that Arsenic in its highest state of oxidation (AsO5) is closely analogous to Phosphoric Acid (PO5), a compound which exists largely in the body. We may therefore suppose that it is less likely to prove irritating than in the condition of Arsenious Acid, which is one of lower oxidation. That such is the case he found by clinical experiments. In several instances where Liq. Arsenicalis produced constitutional disturbance, evidenced by nausea, irritation, and swelling of the eyelids, &c., he found that the Arseniate of Soda in corresponding doses was borne without the slightest discomfort, whilst it appeared to exercise all the curative powers of Arsenic. He concludes that the Arseniate of Soda is less irritating than the Arsenite when the amount of Arsenic given is the same.§
Offic. Prep. Liquor SodAe Arseniatis (Arseniate of Soda, rendered anhydrous by a heat not exceeding 300°, grs. iv.; Distilled Water fl. oz. j. Dissolve). The salt is ordered to be dried in order to avoid the possibility of error arising from the different quantities of water with which the salt crystallizes. The amount of Metallic Arsenic in the solution of the Arseniate of Soda is to that in the Solution of Arsenite of Potash in the proportion of 1 to 2, or as 99 to 186 (Garrod). || Dose, iv. - x., or more.
Dose of crystallized Arseniate of Soda, gr. 1/15 - gr. 1/3; of the salt dried at 300°,
* On the Treatment of Stone in the Bladder, 8vo, 1842.
On the Chemical Discrimination of Vesical Calculi, 1843.
Med. Times and Gaz., March 12 1864. § Ibid. || Ibid.