34 CHEMICAL PHYSIOLOGY. 



Add these fluids to two separate test-tubes of the solution 

 of COHb, and observe that the two absorption bands are not 

 affected thereby. There is no difference on shaking the 

 solution with air, as the compound is so very stable. 



(c.) To a fresh portion of the solution of carbonic oxide 

 haemoglobin add a 10 per cent, solution of caustic soda = 

 cinnabar-red colour. Compare this with a solution of oxy- 

 hremoglobin similarly treated. The latter gives a brownish- 

 red mass. 



11. IV. Acid-Hsematin. 



(a.) To diluted defibrinated blood add water and about 

 1 cc. of acetic acid, and warm gently, when the mixture be- 

 comes brownish owing to the formation of acid-hsematin. 



(6.) Observe the spectrum of (a.\ noting one absorption 

 band to the red side of D near (Fig. 5, 5). Observe that 

 there is considerable absorption of the blue end of the 

 spectrum. 



(c.) The single band is not affected by the usual reducing 

 agents, ammonium sulphide or Stokes's fluid. 



N.B. If acetic acid alone be used to effect the change, observe 

 that only one absorption band is seen. 



12. Acid-Haematin in Ethereal Solution. 



(a.) To defibrinated blood add ether and a large quantity 

 of strong acetic acid, which makes the mixture brown. 

 Shake vigorously, and a dark-brown ethereal solution of 

 haematin is obtained. 



(6.) Observe the spectrum of this solution -four absorp- 

 tion bands are obtained, one in the red between and D, 

 corresponding to the watery acid-hsematin solution ; a narrow 

 faint one near D, one between D and E, and a fourth be- 

 tween b and F (Fig. 5, 5). The last three bands are seen 

 only in ethereal solutions, and require to be looked for with 

 care. 



13. V. Alkali-haematin. 



(a.) Take a solution of acid-haematin ; neutralise it with 

 caustic soda until there is a precipitate of hsematin; on 



