VI.] THE COLOURED BLOOD CORPUSCLES. 53 



Observe the many-banded spectrum of a solution of potassic 

 permanganate. 



(b.) To an alkaline solution of methsemoglobin add ammonium 

 suljDhide. This gives the spectrum first of oxy-haemo.ulobin and 

 then of tuiemoglobin ; and on shaking with air, oxy-hamoglobin is 

 formed. 



(c.) To a solution of oxy-hajmoglohin add a crystal or two of potassic 

 chlorate ; dissolve it with the aid of gentle heat ; after a short time the spec- 

 trum of methsemoglobin is obtained. 



(fl.) Action of Nitrites. — To diluted defibrinated ox -blood, or 

 preferabl)' that of a dog, add a few drops of an alcoholic solution of 

 amyl nitrite. The blood immediately assumes a chocolate colour 

 {Gamgee). 



(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. 



(<7.) Observe the spectrum of (c?.) and {e.). The hand 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 m (/.) the spectrum 

 changes as desciibed in (a.). Add ammonium sulphide or Stokes's fluid, the 

 spectrum of reduced haemoglobin appears, and on shaking up with air, the 

 bands of oxy-hsemoglobin appear. 



(h.) Crystals of Methaemoglobin. — To a litre of concentrated solution of 

 haemoglobin add 3-4 cc. of a concentrated solution of fenicyanide of potassium 

 and also a quarter of a litre of alcohol, and freeze the mixture. After two 

 days, brown crystals of methaemoglobin separate. 



(?'.) To a few cc, of defibrinated blood (rat, guinea-pig), add an equal 

 number of drops of amyl nitrite, and shake the mixture vigorously for a 

 minute or two = dark chocolate tint of methaemoglobin. A drop of this fluid 

 transferred at once to a slide, and covered, yields crystals of methaemoglobin 

 {Halliburton), 



17. VII. Hsematoporphyrin (iron-free h3?matin CigHigNgO). 



(a.) To some strong sulphuric acid in a test-tube add a few 

 drops of undiluted blood (abou.t 5 drops of blood to 8-10 cc. 

 of H.^SOJ ; mix by shaking, when a clear violet-red cr purple-red 

 fluid is obtained. 



(6.) Observe two absorption-bands, one close to and on the red 

 side of D, and a second half-way between D and K. 



(c.) To some of this violet-red solution add a large excess of water, which 

 throws down part of the haimatoporj)hyrin in the form of a brown precipitate, 

 which is more copious if tlie acid be neutralised with an alkali, e.[/., caustic 

 soda. Dissolvfe some of the l)rowu deposit in caustic soda, and examine it 

 spectroscopically. 



