Developed circa 1900 and often called the Tallquist Method, it is used to compare a patient's blood color to a chart of red colors to diagnose possible anemia. The method is still used when more sophisticated equipment is unavailable. This booklet of absorbent papers and a color scale of reds is undated but appears to be from the early quarter of the 20th century. A health care provider takes a patient's blood sample on the perforated, absorbent paper then holds the sample under the holes in the color chart to decided which color matches best. Hemoglobin is an iron containing protein that bonds with oxygen and is responsible for making blood red.