ALBUMENS AND OTHER ORGANIC SUBSTANCES. CREIGHTON. 65 



chloride was warmed. To 5 c. c. of 1.0$ ferric chloride solu- 

 tion 5 c. c. of the white of egg were added in one case^ and in 

 another the chloride was diluted with 5 c. c. of distilled water. 

 These solutions were kept at 65 for ten minutes. At the end 

 of this time the solution containing the albumen was found to 

 be of a deeper colour than the other. To determine whether 

 the non-formation of a precipitate of ferric hydroxide or of 

 Turnbull's blue, in the foregoing experiments, was due to the 

 conversion of the iron into colloidal ferric hydroxide by 

 hydrolysis, sodium acetate was added drop by drop to a solution 

 of ferric chloride, until its colour was somewhat deeper than 

 that of the mixture of white of egg and ferric chloride that 

 had been warmed ; on adding ammonia to the acetate solution a 

 heavy precipitate of ferric hydroxide was thrown down, thus 

 proving that only a small quantity of the iron in the egg solu- 

 tion was in the form of colloidal hydroxide. 



Hydrochloric acid was found to produce a precipitate when 

 added to a solution of ferric chloride and albumen. To a 

 mixture of 5 c. c. of 1$ ferric chloride and 10 c. c, of the white 

 of egg solution a few drops of dilute hydrochloric acid were 

 added. At the end of some minutes no precipitate was observed 

 to have formed. With several c. c. of the acid, however, a 

 precipitate was slowly thrown down. The precipitate was 

 filtered off, and to different portions of the light yellow filtrate 

 ammonia, haematoxylin, potassium ferrocyanide, and potassium 

 sulphocyanide were added. In each case the usual reaction for 

 ferric iron took place. Further addition of hydrochloric acid 

 precipitated no more alubumen from the filtrate. On boiling 

 some of the filtrate, albumen coagulated and was thrown out of 

 solution. This was filtered off and potassium ferrocyanide 

 added to the almost colourless filtrate. The dark blue precipitate 

 was removed by filtration. On boiling the colourless filtrate a 

 light blue flocculent precipitate separated from the solution. 

 The results obtained in this experiment point to the existence of 

 a complex of the iron salt with the albumen. This complex is 



