10 CONCERNING THE RULES AND APPLIANCES 



Every examination of blood by means of the Hsemometer 

 must consist of these three operations : — i. — To obtain and 

 measure the blood. 2. — To dissolve it in water, and to fill 

 the instrurnent with this solution. 3. — To arrange the instrument 

 and read the results. 



This apparatus consists of a small and simply constructed 

 horse-shoe base, composed of a foot, column, mirror, and 

 table. Beneath the table is a frame which bears the glass wedge, 

 K, the latter being propelled by the milled-head screw, R. Upon 

 the table is a cylindrical vessel, G, the one-half of which {a) is 

 filled with blood which has been diluted with water, so as to be 

 examined. The other half {a) is filled with pure spring water, 

 after a tube, whose capacity has been exactly guaged, has itself 

 been filled with blood by capillary action. It is brought into the 

 half of the vessel at «, where the blood contained in the tube 

 dissolves in the water until it becomes a perfectly transparent 

 liquid. By the optical conditions of the apparatus it becomes 

 possible, under an illumination of oil lamps, candles, or gas light, 

 to find a position of the glass wedge, K^ at which the colour and 

 brightness of every such blood solution is exactly the same. This 

 point is sought by moving the wedge backwards and forwards by 

 means of the micrometric screw, 7] and by giving the reflector a 

 definite position, S. 



Upon the frame which surrounds the wedge, a scale, P^ is 

 engraved, a part of which is visible through the aperture at M. 

 This gives exact results in percentage of the amount of haemo- 

 globin in a certain blood solution. There is also a stationary 

 index line on the side of the aperture, M^ which points also to the 

 discovered amount on the scale. 



This Hsemometer presents the following advantages : — 



I. — Easy and convenient management of the apparatus. 



2. — Rapid and direct results in percentage regarding the degree 

 of normal haemoglobin. 



3. — The small quantity of blood, only a drop, required for 

 the examination. 



It is best to take the blood from the tip of the left middle 

 finger. 



After the skin has been thoroughly washed and carefully dried. 



