Hemoglobin is dark red in color, amorphous, contains iron, and is soluble in alcohol, ether, and chloroform. It is recognized chemically by the addition to the suspected fluid of a few drops of a fresh tincture of guaiac and then followed by an ethereal solution of hydrogen dioxid. The mixture, which is at first milky white, turns a deep blue.

If the dried blood is dissolved in normal salt solution, then warmed and evaporated, glacial acetic acid added and warmed, small reddish-brown rhombic plates of hemin appear.

When brought in contact with sulphuretted hydrogen, hemoglobin combines and forms ferrous sulphid, which is black. This gives rise to the bluish discoloration of the abdominal wall that appears when decomposition has occurred.

Hemoglobin is set free from the erythrocytes through hemolysis, either within the vessels or when the blood has escaped into the tissues. The surrounding structures will be diffusely stained. This is commonly seen post-mortem, particularly in those parts of the liver that are in contact with the intestines. When it is set free within the vessels during life, it may be deposited within the lymph-nodes, spleen, and kidney, forming pigment metastases.