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PHYSIOLOGICAL CHEMISTRY 



FIG. 8q. FLEISCHL'S HEMOMETER 

 (Da Costa.} 



divided, by means of a metal septum, into two compartments of equal 

 capacity. This cylinder is supported in a vertical position by means of 

 a mechanism which resembles the base and stage of an ordinary micro- 

 scope. Underneath the stage is placed a colored glass wedge (see 

 Fig. 91), so arranged as to run immediately beneath the glass 

 bottom of one of the compartments of the cylinder and ground in such a 

 manner that each part of the wedge corresponds in color to a solution 



of hemoglobin of some definite percent- 

 age. The glass wedge is held in a metal 

 frame and may be moved backward or 

 forward by means of a rack and pinion 

 arrangement. A scale along the. side of 

 this frame indicates the percentage of the 

 normal amount of hemoglobin which each 

 particular variation in the depth of color 

 of the ground wedge represents, taking 

 the normal hemoglobin content as zoo. 1 

 In a position corresponding to the posi- 

 tion of the mirror on the ordinary micro- 

 scope is attached a light-colored opaque 

 plate which serves to reflect the light upward through the colored 

 wedge and the cylinder to the eye of the observer. 



In making a determination of the percentage of hemoglobin by this instru- 

 ment the procedure is as follows: Fill each compartment about three-fourths 

 full of distilled water. Puncture the finger-tip or lobe of the ear of the subject by 

 means of a sterile needle or scalpel and, as soon as a drop of blood appears, 

 place one end of the capillary pipette (Fig. 90), which accompanies the instrument, 

 against the drop and allow it to fill by capillary attraction. To prevent the blood 

 from adhering to the exterior of the tube, and so render the determination inac- 

 curate, it is customary to apply a very thin coating of mutton fat to the outer sur- 

 iace before using or to wrap the tube in a piece of oily chamois when not in use. 

 As soon as the tube has been accurately filled with blood it should be dipped into 

 the water of one of the compartments of the cylinder and all traces of the blood 

 washed out with water by means of a small dropper which accompanies the 

 instrument. If the blood is not well distributed throughout the compartment and 

 does not form a homogeneous solution the contents of the compartment should be 

 mixed thoroughly by means of the metal handle of the capillary measuring pipette. 

 When this has been done each compartment should be completely filled with dis- 

 tilled water and the glass cover adjusted, care being taken that the contents of 

 the two compartments do not mix. Now adjust the cylinder so that the compart- 

 ment containing the pure distilled water is immediately above the colored glass 

 wedge. By means of the rack and pinion arrangement manipulate the colored 

 wedge until a portion of it is found which corresponds in color with the diluted 

 blood. When this agreement in color has been secured the point on the scale cor- 

 1 The scale of the ordinary instrument is usually too high. 



