Perl's stain or prussion blue test is for:
Perls' stain (Prussian-Blue Reaction) is to demonstrate Ferric salts in tissues. These are seen as iron  granules in bone marrow macrophages, erythroblasts (Sideroblasts) and erythrocytes (Siderocytes) in  blood ﬁlms and haemosiderin in spun urine.
Bilirubin
Calcium
Hemosiderin
Glycogen