36 CHEMICAL PHYSIOLOGY. 



15. VI. Methsemoglobin. 



(a.) To a medium solution of oxy-h?emoglobin, add a few 

 drops of a 1 percent, solution of potassic permanganate, warm 

 gently, observe the change of colour, and examine it with a 

 spectroscope. If the two bands of oxy-hsemoglobin are still 

 present, allow it to stand for some time and examine again. 

 If they persist, carefully add more permanganate until the 

 two bands disappear. Finally, acidify the solution, and 

 with a spectroscope look for the spectrum of methremoglobin, 

 viz., one absorption band in the red near C, nearly in the 

 same position, but nearer D than the band of acid-hsematin; 

 the violet end of the spectrum is much shaded. Three 

 other bands are described in the green, especially in 

 dilute solutions. On adding ammonia to render the solution 

 alkaline, the band in the red disappears, and is replaced by 

 a faint band near D. 



(b.) To an alkaline solution showing the last described 

 spectrum, add ammonium sulphide or Stokes's fluid. This- 

 gives the spectrum of reduced haemoglobin; and on shaking 

 with air, oxy-hremoglobin is formed. 



(c.) To a solution ofoxy-h?emoglobm, add a crystal or two 

 of potassic chlorate ; dissolve it with the aid of gentle 

 heat ; after a short time the spectrum of methsemoglobin is 

 obtained. 



(d.) Action of Nitrites. To diluted defibrinated ox blood, 

 or preferably that of a dog, add a few drops of an alcoholic 

 solution of amyl nitrite. The blood immediately assumes 

 a chocolate colour. 



(e.) To another portion of diluted blood add a solution of 

 potassic or sodic nitrite. Observe the chocolate colour. 



(/.) To portions of (d.) and (e.) add ammonia, the chocolate 

 gives place to a red colour. 



(g.) Observe the spectrum of (d.) and (e.) The band in 

 the red is distinct, and is best seen when the solution is of 

 such a strength that only the red rays are transmitted. On 

 dilution, other bands are seen in the green. Add ammonia, 

 and with the change of colour described in (f.), the spectrum 

 changes to that described in (a.) Add ammonium sulphide 



