OF HEMOGLOBIN, AND ITS SPECIFICITIES. 77 



vii, 57) gives the percentage for pig's hemoglobin crystals dried over 

 sulphuric acid, then at 115, as 5.9, and for the dog 4. He also reports 

 (Archiv f. ges. Physiologic, 1883, xxxi, 240) that he did not obtain con- 

 cordant results with the crystals of horse's blood. Hiifner and Biicheler 

 (Zeit. f. physiolog. Chemie, 1884, vin, 358) dried horse crystals at over 

 sulphuric acid and anhydrous phosphoric acid, and then found them to 

 contain 3.94 per cent of water. Jacquet (Zeit. f. phys. Chemie, 1889, xiv, 

 289) records that air-dried crystals of the dog lost 11.39 per cent of water 

 at 115, and those of the chicken 9.333 per cent. Hiifner (Archiv f. ges. 

 Physiologie, 1894, 130) gives the water of crystallization of bullock's blood 

 as being 9.98 per cent. Bohr (Exper. Untersuch. u. d. Sauerstoffaufnahme 

 d. Blutfarbstoffes, Copenhagen, 1885) found that the percentage in bullock's 

 blood varies from 1.2 to 6.3 per cent, which variations may be due, in part 

 at least, to impurities of his preparations. 



THE EXTINCTION COEFFICIENTS AND QUOTIENTS. 



Vierordt, Hiifner, and others have found that reliable extinction co- 

 efficients can not be obtained by measurements of a single spectral field 

 unless the solution contains but a single coloring matter; because, while 

 solutions of a single coloring matter affect the light intensities of the differ- 

 ent regions of the spectrum in constant relationship to each other, irrespec- 

 tive of the strength of the solution, the presence of a second coloring matter 

 alters or destroys this relationship. Therefore, two fields must be measured, 

 and the fields to be selected should be those which are most readily influenced 

 by the differences in the strength of the solution. Moreover, the two 

 coefficients thus obtained serve as mutual checks. The quotient obtained 

 from these coefficients, as shown by Hiifner (Archiv f. Anat. u. Physiologie, 

 Physiolog. Abth., 1894, 130, and 1900, 39) in his studies of oxyhemoglobin, 

 reduced hemoglobin, methemoglobin, and CO-hemoglobin, is absolutely con- 

 stant and distinctive for each substance, and, therefore, departures in extinc- 

 tion coefficients show, according to him, not only the presence of impurities 

 but also the quantity of each coloring matter present. 



Hiifner measured the extinction coefficients of these substances for 

 the mid-region between A and B absorption bands (the interval between 

 the wave lengths 554 and 565 fifi), and for the darkest portion of band B 

 (the interval between 531.5 and 542.5,wu). In such determinations with 

 fresh bullock's blood and solutions of the crystals of bullock's oxyhemo- 

 globin he found constant results. The quotient for oxyhemoglobin was 

 1.578, for reduced hemoglobin 0.7617, for CO-hemoglobin 1.095, and for 

 fresh rabbit's blood 1.579. Zeynek (Archiv f. Anat. u. Physiologie, Phys. 

 Abth., 1899, 460) by the same means determined for methemoglobins of 

 the horse 1.187, and of the pig 1.183. Hiifner in the later article states 

 that the oxyhemoglobin quotient (1.578) and the reduced hemoglobin 

 quotient (0.762) have each the same value independent of the degree of 

 concentration of the solution and the species of blood. 



Von Noorden (Zeit. f. phys. Chemie, 1880, iv, 9) found the mean quo- 

 tient for pure oxyhemoglobin of the dog to be 1.324, for the guinea-pig 



