FERROCYANIDE n.
prussian blue. It is obtained by strongly heating together potash, scrap iron, and animal matter containing nitrogen, as horn, leather, blood, etc., in iron pots.
FILTER n.
al, through which water or other liquid may passed to cleanse it from the solid or impure matter held in suspension; a chamber or device containing such substance; a strainer; also, a similar device for purifying air. Filter bed, a pond, the bottom of which is a filter composed of sand gravel. -- Filter gallery, an un…