64 BEHAVIOUR OF IRO.V SALTS, I.V THE PRESENCE OF 



dilute sodium chloride solution. These solutions were filtered 

 before using. 



Haematoxylin: A 0.5$ solution of haematoxylin was used in 

 the following experiments. 



(a) Experiments ivith ferric cliloride. 

 To 10 c. c. of 1.0$ ferric chloride solution 10 c, c. of the 

 white of egg solution were added and the mixture divided into 

 two parts. One portion was allowed to stand at room tempera- 

 ture for a few minutes, and the other kept at 60 for the same 

 length of time. The two portions were divided into several 

 parts and treated with different reagents. The following 

 results were obtained : 



With NaOH no precipitate formed. 

 " r NH 4 OH no precipitate formed. 

 " K 8 Fe(CN) 6 no change. 

 " K 3 Fe(CN) 6 slight blue precipitate formed. 

 " KCNS deep red colouration. 

 " (NH 4 ) 2 S black precipitate formed. 

 " Haematoxylin violet black colouration appeared. 

 Similar results were obtained when 10 c. c. of either the 

 serum albumen or the egg albumen solutions were employed 

 instead of the white of egg solution. It was found with these 

 substances that some of the reagents caused albumen to 

 separate from the solution. Control experiments, in which 

 the albumen .solution was replaced by an equal volume of dis- 

 tilled water, were carried out. In these it was found that 

 sodium hydroxide, ammonium hydroxide, potassium ferri- 

 cyanide, and potassium ferrocyanide all threw down the usual 

 precipitates. 



On addition of the albumen solutions to the ferric chloride, 

 it was observed that the brownish colour of the mixtures 

 gradually deepened on standing, thus suggesting that albumen 

 increased the degree of hydroysis of the iron salt. This result 

 was also observed when a mixture of white of egg and ferric 



