Figure 1. Visible absorption 



spectra of beef o.xy- 



haemoglobin. 



The concentration of the oxyhaemoglobin solution was 0-2 per cent, the depth 

 of the absorption vessel 18 mm. A Schmidt and Haensch spectrograph with grating 

 lattice was used. The width of the slit was 0T mm, the time of exposure was 

 3 seconds. As source of light for the spectra (a)-(f ) a bulb with tungsten filament 

 was used. It was replaced by a mercury arc for the wavelength spectra (Figure 1). 

 Spectrum (b) was obtained by reducing the solution (a) with a trace of solid sodium 

 dithionite. About 1 ml of a 15 per cent solution of the beef oxyhaemoglobin was 

 brought into a Kjeldahl flask and dried by reducing the pressure to 10-15 mm of 

 Hg and dipping the flask into a water bath of 35-40 C. A tube containing dry 

 calcium chloride was inserted between the neck of the flask and the pump, so that 

 the water vapours did not condense in the neck of the flask. The spectrum of 

 oxyhaemoglobin was replaced very quickly by that of reduced haemoglobin and 

 then upon drying of the wet substance, by the spectrum of dry haemoglobin (c). 

 Spectrum (d) was obtained by mixing solution (a) with one tenth of its volume of 

 10 per cent NaOH solution, keeping the alkaline mixture in a boiling water bath 

 for two minutes, cooling and adding a trace of solid sodium dithionite. Spectrum 

 (e) is the absorption spectrum of oxyhaemoglobin obtained by dissolving the dry 

 haemoglobin (c) in 75 ml of 0-1 per cent sodium carbonate solution. The emission 

 spectrum of the electric bulb is shown by (f), the absorption vessel in this case 

 being filled with distilled water. Panchromatic films were used for the spectra 

 shown in Figure 1. The alterations of the absorption spectra could be demon- 

 strated particularly distinctly by using coloured Ansco films as demonstrated at 

 the Conference. 



