ESTIMATION OF HEMOGLOBIN 123 



the same is a scale graduated so as to indicate the percentage of hemoglobin 

 corresponding to the shades of the different parts of the wedge. This frame- 

 work can be moved by the wheel T which fits into a rack on its lower surface. 

 The scale can be read through a small opening M in the plate. Into the 

 large circular opening of the plate fits a cylindrical metal cell G with a glass 

 bottom and divided by a metal partition into two equal parts. One of these 

 halves lies over the wedge and is filled with distilled water. The other con- 

 tains the solution of blood in which the hemoglobin is to be estimated. The 

 apparatus is usually supplied with three cells. Of these, the first two are 

 used in estimating the hemoglobin according to Miescher's modification 

 of FleischPs original method. This is the method now generally used. 

 These cells are furnished with a glass cover having a groove which fits 

 upon the partition of the cell. Over this cover is placed a diaphragm 

 with a longitudinal slit, which only permits of the central part of each 

 side of the cell being seen. The third cell is for use when the original 

 Fleischl method is employed. 



The patient's ear or finger is pricked, and the blood from the wound 

 sucked up into the graduated pipet until it reaches the mark , , or |, a 

 one per cent solution of sodium carbonate is then sucked in until the upper 

 mark is reached. The pipet is then well shaken in order to mix the blood 

 thoroughly. One-half of each of the two cells, which are respectively 12 

 and 15 millimeters high, are then filled with the mixture, the other half 

 being filled with water. An important point is that the liquids should com- 

 pletely fill the cells. The cover-glasses and diaphragms are then applied 

 and the cells are ready for examination. This must be done by artificial 

 light. Moreover, in order to have accurate results, light of the same inten- 

 sity should be always used. One of the cells is placed on the plate and the 

 wheel T turned until the colors of the two halves exactly correspond. When 

 this point is reached, the result is read off on the scale through the opening M. 

 This should be repeated several times with each of the cells, and the average 

 of the readings taken. The result obtained with the 12-millimeter cell 

 should be multiplied by J to bring it up to that of the larger. For example, 

 suppose the result of several readings to be: 



With the large cell (15 mm.) 54- 



With the small cell (12 mm.) 42.00 



If the readings obtained with the large cell are exactly correct, then the read- 

 ings with the smaller one should be 43.2, since 54 X =43.2. Or, if the 

 readings with the smaller cells are exact, the readings with the larger should 

 be 52.5, since 42X1=52.5. Hence the mean of 54 and 52.5, namely 53.25, 

 should be taken as the correct figure. On looking at the corrected table of 

 hemoglobin values supplied with each instrument, we would find that this 

 number on the scale corresponds to a solution containing 400 milligrams 



