472 CHEMISTRY OF THE PROTEIDS CHAP. 



these two fractions so act upon one another as to prevent either giving 

 the reactions which it otherwise would. Kiihne showed in 1866 that 

 the albumin reactions are only obtained when the haemoglobin has 

 been decomposed and its iron-containing fraction, the haematin, has 

 been set free ; while, for example, cupric and ferrous sulphates, mer- 

 curic chloride, silver nitrate, neutral and basic lead acetates precipitate 

 ordinary albumin, they produce no effect on oxyhaemoglobin, but do 

 precipitate the globin as soon as by decomposition of the haemoglobin 

 it has become separated from the haematin. On the other hand, 

 the iron cannot be demonstrated in haemoglobin till the latter is 

 decomposed, and thereby the ' masked ' iron is converted into ionic 

 iron. 



How readily acids change haemoglobin is fully discussed later on 

 (p. 496). Why the salts of the heavy metals such as mercuric chloride 

 do not precipitate (Preyer 1 ) is difficult to say, but if we bear in 

 mind that pure salt-free albumins are also not precipitated, the ex- 

 planation already offered by the author seems to hold good : Salt-free 

 albumins are in the true sense of the word dead, because, by the 

 removal of all electrolytes, the electrical dissociation of amino-acids is 

 prevented, and from the active amino-acids we pass to the inactive 

 ring-compounds (see p. 211), and it is quite conceivable that the Hg- 

 kation of corrosive sublimate is not sufficiently strong to convert the 

 amino-acids in the globin radical from their pseudo-acid pseudo-basic 

 state into chemically active open-chain compounds. Salkowski 2 and 

 Formanek 3 have found that haemoglobin differs from other albumins 

 in being precipitated when it is shaken with a little chloroform, and 

 that it does not become altered hereby. 



Hoppe-Seyler 4 and others have drawn attention to the great resist- 

 ance which haemoglobin offers to putrefying organisms ; oxyhaemoglobin 

 becomes changed into reduced haemoglobin, but does not undergo any 

 further change. Haemoglobin also resists try psin very strongly, especially 

 as long as it is in living red corpuscles. 5 " To what extent this immunity 

 of haemoglobin depends on the admixture of antiferments, or is simply 

 a widely distributed general property of pure colloidal albumins, is 

 as little understood as in the case of serum-albumins " (Cohnheim). 

 The author is not convinced of the existence of antiferments : given a 

 ferment and an albumin capable of being acted upon, then a third 



1 W. Preyer, Plugers Archiv, 1. 395 (1868). 



2 E. Salkowski, Deutsche medizin. Wochensch. 1888, No. 16 ; Zeitschr. f. 

 Chem. 31. 329 (1900). 



3 E. Formanek, ibid. 29. 416 (1900). 



4 F. Hoppe-Seyler, Zeitschr. f. physiol. Chem. 1. 121 (1877). 

 6 H. Sachs, Munchener medizin. Wochenschr. 1902, p. 189. 



