Section 172.490 - Yellow prussiate of soda(a) The food additive yellow prussiate of soda (sodium ferrocyanide decahydrate; Na4Fe(CN)6·10H2O contains a minimum of 99 percent by weight of sodium ferrocyanide decahydrate.(b) The additive is used or intended for use as an anticaking agent in salt and as an adjuvant in the production of dendritic crystals of salt in an amount needed to produce its intended effect but not in excess of 13 parts per million calculated as anhydrous sodium ferrocyanide.42 FR 14491, Mar. 15, 1977, as amended at 58 FR 17098, Apr. 1, 1993