62 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



9. When concentrated nitric acid of 1.48 specific gravity 

 is added to some of the solution, the precipitate first formed 

 redissolves to a clear bright-yellow fluid as soon as the volume 

 of nitric acid added is equal to half the volume of the albumin 

 solution (distinction from egg-albumin). 



10. On shaking some of the solution with an equal volume 

 of ether, no coagulation, or at least only a very slight one, 

 results (distinction from egg-albumin). 



11. Add to some of the solution half its volume of caustic 

 soda of 1.34 specific gravity and a few (3) drops of a neutral 

 solution of lead acetate and heat: it turns brown or black 

 (distinction from egg-albumin, which gives a much darker 

 solution) ; when acidified with hydrochloric acid there is soon 

 obtained a grayish-yellow cloudy fluid (distinction from egg- 

 albumin). The reaction depends on the splitting off of sul- 

 phur and the formation of lead sulphide. 



Dilute the albumin solution with nine times its volume 

 of water (10 cc. diluted to 100 cc.) for the following experi- 

 ments: 



Reactions of very Dilute Solutions of Albumin. 



1. Heat to boiling: no change. Then add nitric acid 

 and heat again: precipitation of coagulated albumin. 



2. Add acetic acid and potassium ferrocyanide solution: 

 cloudiness and then a flocculent precipitate. 



3. Acidify with hydrochloric acid and then add phospho- 

 tungstic acid: voluminous gelatinous precipitate. 



4. With tannin solution, precipitation takes place, and 

 also, 



5. With mercuric chloride solution (soluble in sodium 

 chloride solution). 



6. Add some Millon's reagent and heat to boiling: coagu- 

 lum, which gradually turns reddish to brick-red. This reac- 



