VI.] THE COLOURED BLOOD CORPUSCLES. 53 



Observe the many-banded spectrum of a solution of potassic 

 permanganate. 



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

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

 then of hemoglobin : and on shaking with air. oxy -hemoglobin is 

 formed. 



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

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

 trum of methaemoglobin 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. 



(flr.) Observe the spectrum of (d.) and (<?.). The band in the red is distinct, 

 ami is best seen when the solution is of such a strength that only the red ravs 

 are transmitted. On dilution, other bands are seen in the green. Acid 

 ammonia, ami with the change of colour described in (f.) 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. 



(h.) Crystals of Methsemoglobin. 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 methaemoglobin 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 methaeinoglobin. A drop of this fluid 

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

 (Halliburton'). 



17. VII. Hsematoporphyrin (iron-free ha?matiri C ]6 II 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 HgSO^) ; 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 haematopurphyrin in the form cf a brown precipitate, 

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

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

 spectroscopically. 



