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acetate of lead. He considers it to have three absorption- 

 bands — one like but not identical with that of acid Hsematin, 

 the other two identical with those of Oxyhemoglobin. He 

 hence regards as Methcemoglobin what Hoppe-Seyler would 

 regard as a mixture of Methtemoglobin and O-Haemoglobin. 



At the meeting of the British Association, at Norwich, 

 Professor Heynsius stated that a pupil of his had succeeded, 

 by passing CO. gas through a solution of Haemoglobin, in 

 converting it completely into Heematin (as proved spectro- 

 scopically) ; and that then, by addition of a small quantity of 

 ammonia and subsequently of Stokes' reducing fluid, the 

 single band of Stokes' reduced Hsemoglobin could be obtained, 

 and on agitation with air the bands of Oxyhsemoglobiu, 

 proving a reformation of Hfemoglobin after it had been broken 

 down to the condition of Haematin. (See ' Journal of Ana- 

 tomy and Physiology,' November, 1868.) 



I am led to a different conclusion by repeating this experi- 

 ment, and find that Haematin is not formed, but simply 

 Methsemoglobin. When CO2 gas is passed for an hour 

 through a dilute solution of Haemoglobin, the two Oxyhaemo- 

 globin bands entirely disappear, and give place to two new ones 

 — one in the red near to, but somewhat nearer blue than, 

 the chief band of acid Hacmatin ; the second, broad and diffi- 

 cult at first to detect, stretching from near the solar line h to 

 F. No precipitation of an albumen occurs in this process. 

 If to part of the solution with these bands ammonia is added, 

 no precipitate occurs. If to another part some strong acetic 

 acid is added, the colour changes to a browner tint, the band 

 between h and F fades, and the true first band of acid Hacma- 

 tin in the red becomes sharply defined. The other bands of 

 acid Haematin are very faint, and it is unnecessary to allude 

 to them here. It is very important to observe that when 

 ammonia in small quantity is added to the solution treated 

 with strong acetic acid a jlocculent ^^^''^cipitate is produced. 

 Thus we have a radical distinction between the product of 

 the action of carbonic acid and that of strong acetic acid. 

 The first alters the Haemoglobin molecularly, so as to afford a 

 totally new set of absorption bands, but it does not break it 

 up chemically. The second, on the other hand, distinctly 

 destroys the chemical structure of the Haemoglobin ; it de- 

 taches Haematin from an albuminoid constituent, and this 

 albumen remains in solution in the excess of acetic acid ; it 

 is immediately precipitated on neutralization of the acid by 

 ammonia. The converse experiment of addition of ammonia 

 to Haemoglobin, and precipitating the detached albumen by 

 neutralizing with acetic acid, is mentioned by Preyer. 



