fluosilicic acid: an unstable poisonous corrosive acid known primarily in the form of its salts
acid: any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
agglutination test: a blood test used to identify unknown antigens; blood with the unknown antigen is mixed with a known antibody and whether or not agglutination occurs helps to identify the antigen; used in tissue matching and blood grouping and diagnosis of infections