Every clinician and surgeon recognizes the importance of hemoglobin estimation in affording valuable additional data in the diagnosis of certain diseases and conditions. By means of such blood examinations, the progress of the patient's condition can be watched from time to time during the treatment of the disease. In blood transfusion work its useful application has been shown by Libman and Ottenberg.1 They recommend an easy working formula using hemoglobin estimation and body weight for calculating the amount of blood necessary to raise the hemoglobin of the recipient to a certain percentage. Blood taken from a donor can be calculated in the same manner.
The value of a reliable and convenient clinical method is obvious. An ideal clinical method should be one easy of manipulation, accurate, rapid and, if possible, utilizing an instrument both portable and inexpensive. The estimation of hemoglobin is obtained in several ways: first, directly, (a