Prussian Blue

(Chem.) A valuable pigment prepared by adding a solution of ferro-cyanide of pota ium to exce of a per-salt of iron; it is an insoluble dark blue precipitate which has a coppery lustre when in lumps. On the large scale, it is frequently prepared by proce es which yield an impure product of an inferior color. Form. Fe4Fcy3Prus's ia Proper, a prov. of the kingdom of Pru ia, constituting its N.E. portion, and b. E. and S.by Ru ia and Poland. It is divided into East and West Pru ia, of which the respective caps. are Königsberg and Dantzig. Surface, generally level, with a soil of medium fertility. Pop. 3,090,960. [s. 738]