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302 THE BLOOD.
sides containing a layer of liquid 1 cm. thick (Hoppe-Seyler’s hsematinom-
eter). The use of Hoppe-Seyler’s colorimetric double pipette is more
advantageous. Other good forms of apparatus have been constructed
by Giacosa and Zangermeister.1
Instead of an oxyhemoglobin solu-
tion we now generally use a carbon-monoxide haemoglobin solution as
a standard liquid because it may be kept for a long time. The blood
solution in this case is saturated with carbon monoxide.2
The quantitative estimation of the blood-coloring matters by means
of the spectroscope may be done in different ways, but at the present
time the spectrophotometric method is chiefly used, and this seems to be
the most reliable. This method is based on the fact that the extinction
coefficient of a colored liquid for a certain region of the spectrum is directly
proportional to the concentration, so that C : E= Ci : E\, when C and
C\ represent the different concentrations and E and E\ the corresponding
C C.
coefficients of extinction. From the equation —=-=r7 it follows that for
hi tii\
one and the same pigment this relation, which is called the absorption
ratio, must be constant. If the absorption ratio is represented by A,
the determined extinction coefficient by E, and the concentration (the
amount of coloring-matter in grams in 1 cc.) by C, then C = AE.
Different forms of apparatus have been constructed (Vierordt and
Hufner 3
) for the determination of the extinction coefficient, which is
equal to the negative logarithm of those rays of light which remain
after the passage of the light through a layer 1 cm. thick of an absorbing
liquid. In regard to this apparatus the reader is referred to other text-
books.
For purposes of control the extinction coefficients are determined in two dif-
ferent regions of the spectrum. Hufner has selected (a) the region between the
two absorption-bands of oxyhemobglobin, especially between the wave-lengths
554 nn and 565 n^ and (b) the region of the second band, especially the inter-
val between the wave-lengths 531.5 mm and 542.5 mm- The constants or the
absorption ratio for these two regions of the spectrum are designated by Hufner
by A and A’. Before the determination the blood must be diluted with water,
and if the proportion of dilution of the blood be represented by V, then the con-
centration or the amount of coloring-matter in 100 parts of the undiluted blood
is
C = 100. V. A. E and
C = 100. V.A’.E’.
The absorption ratio or the constants in the two above-mentioned regions
of the spectrum have been determined for oxyhemoglobin, haemoglobin, carbon-
monoxide hemoglobin, and methemoglobin, as follows:
Oxyhemoglobin A =0.002070 and A’ =0.001312
Hemoglobin A r =0.001354 and A’r =0.001778
Carbon-monoxide hemoglobin. .A<- =0.001383 and A’c =0.001263
Methemoglobin Am =0.002077 and A’m = 0.001754
1
F. Hoppe-Seyler, Zeitschr. f. physiol. Chem., 16; G. Hoppe-Seyler, ibid., 21;
Winternitz, ibid.; Giacosa, Maly’s Jahresber., 26; Zangermeister, Zeitschr. f. Biol-
ogic, 88.
-
See Haldane. Journ of Physiol., 26.
3
See Vierordt. Die Anwondung des Spektralapparates zu Photometrie, etc. (Tubin-
gen, 187 3), and Hufner. Arch. f. (Anat. u.) Physiol., 1894, and Zeitschr. f. physiol
Chern , 3, v. Noorden, ibid . 4; Otto, Pfluger’s Arch, 31 and 36.
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