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 

 sulphide. This gives the spectrum first of oxy-hsemoglobin and 

 then of haemoglobin ; and on shaking with air. oxy-hsemoglobin is 

 formed. 



(o.) To a solution of oxy -haemoglobin add a crystal or two of potassic 

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

 trum of methseinoglobin 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 

 (Gamyee). 



(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 (/.) the spectrum 

 changes as described 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 -haemoglobin appear. 



(A.) Crystals of Methaemoglobin. To a litre of concentrated solution of 

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

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

 days, brown crystals of methseinoglobin separate. 



(i. ) 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 methsemoglobin. A drop of this fluid 

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

 (Halliburton^. 



17. VII. Hsematoporphyrin (iron-free h^matiri C J6 H 18 N 2 0). 



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

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

 of IT 2 S0 4 ) ; 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. 



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

 throws down part of the hsematoporphyrin in the form of a brown precipitate, 

 which is more copious if the acid be neutralised with an alkali, e.g., caustic 

 soda. Dissolve sorm of the brown deposit in caustic soda, and examine it 

 spectroscopically. 



