62 BEHAVIOUR OF IRON SALTS, IN THE PRESENCE OF 



of a soluble complex ion brought about by the entrance of the 

 metal into the hydroxyl group of these substances. 



It has long been known that albumen manifests a marked 

 tendency to hinder many chemical reactions. The cause of this 

 may be either physical or chemical, von Meyer and Lotter- 

 moser 1 have shown, for instance, that small quantities of egg 

 albumen prevent the precipitation of silver hydrosol by salts. 

 The effect of albumen on the ionization of silver nitrate has 

 been investigated by Galeotti 2 who found, that small quantities 

 greatly diminish the concentration of the silver ions. It is 

 possible that albumen may, in some cases, diminish the ioniza- 

 tion of a substance to such an extent as to prevent its recogni- 

 tion by the usual tests. Albumen readily forms complexes with 

 salts of both the alkali and the heavy meitals, as well as with 

 many bases and all the mineral acids except ortho- and 

 pyro-phosphoric acid. These albumen compounds may be 

 divided into two classes : those in the which the metal is present 

 as a simple cation ; and those in which it forms part of a com- 

 plex anion, and in which, for this reason, its presence cannot 

 be demonstrated by ordinary reagents. Complexes formed by 

 albumen with HC1, HNO 8 . H 2 SO 4 , NaOH, KOH, NaCl, KC1, 

 MgCL, CaCl 2 , (Ntt 4 ) 2 S0 4 , McrS0 4 , Na 2 S0 4 , and K 2 S0 4 have 

 recently been studied by Mayer 3 . The existence of the complex 

 can often be readily shown. For example, when hydrochloric 

 acid is added to a solution of white of egg and the mixture 

 filtered so as to remove the precipitate which forms, it is found 

 that no silved chloride is thrown down on the addition of silver 

 nitrate to the filtrate. With salts of most of the heavy metals 

 albumen forms compounds of the type 4 



MO. G^N^SO*; 

 but with iron salts the compound is more complex 5 . These 



1. von Meyer, E..and A. Lottermoser : J pr. Chem., 56, (2)214, (1897). 



2. Galeotti, G. : Zeitschr. physiol. Chem. 42, 330, (1904). 



3. Mayer, A. : Compt. rend.. 143, 515, (1906). 



4. Piotrow&ki : Jahsesber. uber die Fortschritt der Chemie, 534, (1857). 



5. BrQoker : Zeitchr. ftr Chemie, 61 (1871). 



