124 THE BLOOD 



of hemoglobin per 1,000 cubic centimeters of solution. But our original 

 dilution was either i : 200, i : 300, or i : 400, according as our pipet had been 

 filled with blood up to the mark ^, , or ^; so that in order to obtain the actual 

 percentage of hemoglobin in the blood under examination we should be 

 obliged to multiply our result by 200, 300, or 400. In the example we have 

 taken, the amount of hemoglobin would be, if our dilution was i : 200, 400 X 

 200=80,000 milligrams = 80 grams in 1,000 cubic centi meters 8 grams 

 in 100 cubic centimeters, or 8 per cent. 



Another very simple method of approximately determining the hemo- 

 globin percentage is the hemoglobin scale devised by T. W. Talquist. This 

 consists of a series of shades of color corresponding to undiluted blood of 

 various hemoglobin values, ranging from ten to one hundred per cent of an 

 arbitrary scale. This scale is included in a book, the remaining pages of 

 which consist of filter paper, which is used for absorbing the specimen of 

 blood whose hemoglobin percentage is to be estimated. The blood-stained 

 filter paper is compared with the hemoglobin scale by direct daylight until 

 a shade is found with which it corresponds. For approximate results this 

 method has proved very satisfactory. 



Derivatives of Hemoglobin. Hematin. By the action of heat cr 

 of acids or alkalies in the presence of oxygen, hemoglobin can be split up 

 into a substance called Hemaiin, which contains all the iron of the hemo- 

 globin from which it was derived, and a proteid residue. Of the latter it is 

 impossible to say more than that it probably consists of one or more bodies 

 of the globulin class. If there be no oxygen present, instead of hematin a 

 body called hemochr onto gen is produced, which, however, will speedily under- 

 go oxidation into hematin. 



Hematin is a dark brownish or black non-crystallizable substance of 

 metallic luster. Its percentage composition is C, 64.30; H, 5.50; N, 9.06; 

 Fe, 8.82; O, 12.32; which gives the formula C^HyoNgFeaO^ (Hoppe- 

 Seyler). It is insoluble in water, alcohol, and ether; soluble in the caustic 

 alkalies; soluble with difficulty in hot alcohol to which is added sulphuric 

 acid. The iron may be removed from hematin by heating it with fuming 

 hydrochloric acid to 160 C., and a new body, hematoporphyrin, the so-called 

 iron-free hematin, is produced. Hematoporphyrin (C^^NgO^, Hoppe- 

 Seyler) may also be obtained by adding blood to strong sulphuric acid, and 

 if necessary filtering the fluid through asbestos. It forms a fine crimson 

 solution, which has a distinct spectrum, viz., a dark band just beyond D, 

 and a second all but midway between D and E. It may be precipitated from 

 its acid solution by adding water or by neutralization, and when redissolved 

 in alkalies presents four bands, a pale band between C and D, a second 

 between D and E, nearer D, another nearer E, and a fourth occupying the 

 chief part of the space between b and F. 



Hematin in Acid Solution. If an excess of acetic acid is added to 



