HEMOGLOBIN ESTIMATION. 



139 



scale is the proper one; if the 12 millimeter cell is used, the reading 

 is only 4/5 of what it should be. Thus a reading of 100% with the 15- 

 millimeter cell would show with the 12-millimeter one a reading of 

 80% for the same blood. The apparatus is quite expensive and 

 requires considerable time in making the estimation. 



Sahli's Haemometer. A simple and ap- 

 parently very scientific instrument which has 

 been recently introduced is the Sahli modifi- 

 cation of the Gower haemoglobinometer. In- 

 stead of the tinted glass, or gelatin colored 

 with picrocarmine to resemble a definite blood 

 dilution, Sahli uses as a standard the same 

 corloring matter as is present in the tube 

 containing the blood. By acting on blood 

 with 10 times its volume of N/io HC1, 

 haematin hydrochlorate is produced, which 

 gives a brownish-yellow color. In the 

 standard tube, which is sealed, a dilution 

 representing i% of normal blood is used. 

 To apply this test, pour in N/ 10 HC1 to the 

 mark 10 on the scale of the graduated tube. 

 Add to this 20 cubic millimeters of the blood 

 to be examined, drawn up by the capillary 

 pipette provided. So soon as the mixture 

 assumes a clear brown color, add water drop 

 by drop until the color of the tubes matches. 

 The reading of the height of the aqueous 

 dilution on the scale gives the Hb. reading. 

 The tubes are encased in a vulcanite frame 

 with rectangular apertures. This gives the 

 same optical impression as would piano -parallel glass sides. It 

 recommended that the N/io HC1 be preserved with chloroform. 



Tallquist's Haemoglobin Scale. This is a small book of specially 

 prepared filter-paper with a color-scale plate of 10 shades of blood 

 colors. These are so tinted as to match blood taken up on a piece 

 of the filter-paper and are graded from 10 to 100. So soon as the 



FIG. 49. Sahli's haemo- 

 globinometer. (Greene.) 



is 



