BY DR. LAUDER BRUNTON. 431 



of its alkali !>}' prolonged washing or by soaking in dilute 

 acids it forms pKRudo^brin. Like fibrin this substance is 

 elastic, and it swells but does not dissolve in dilute hydro- 

 chloric acid. Unlike fibrin it contains no ash, and when put 

 into bydrogeo peroxide does not readily decompose it ; so that 

 few bubbles of gas appear. 



b. From milk. Alkali albuminate may be prepared from 

 milk by shaking with caustic potash and ether, removing the 

 ether, precipitating the albuminate by acetic acid and washing 

 the coagulum with water, alcohol, and ether. 



15. Properties. Boil some pieces of albuminate in water; 

 it still contains alkali, and is soluble in boiling water, forming 

 a feebl} 7 alkaline solution. Let it cool, divide it into several 

 portions and apply the following tests : 



1. Pass CO., through the solution and a precipitate will fall. 

 No precipitate is produced if the solution is strongly alkaline. 



2. Add alcohol to the solution ; no precipitate is produced. 



3. Add magnesium sulphate in substance till the solution is 

 saturated. The albuminate will be precipitated. Calcium 

 chloride will have the same effect. 



It is precipitated })y metallic salts like other albuminous 

 solutions. It is precipitated by neutralization, and behaves 

 to alkaline phosphates like the solution of alkali albuminate 

 prepared by heating solutions of albumin with potash. 



* It is not precipitated by Neutralization in presence of 

 Alkaline Phosphates. A veiy small quantity of acid is suffi- 

 cient to give a distinctly acid reaction to a pure solution of 

 alkali albuminate, but if sodium or potassium phosphate is 

 present a considerable amount of dilute acid may be added to 

 the liquid after the point of neutralization has been reached 

 without given it a very distinctly acid reaction ; for the acetic 

 acid and neutral phosphate react on each other, forming 

 sodium or potassium acetate^and acid phosphate. Whenever 

 the solution becomes/cfistinctly acid, the albumin is precipi- 

 tated, whether sodium phosphate be present or not. If suffi- 

 cient acid has been added to convert all but a trace of the 

 sodium phosphate present into acid phosphate, the further 

 addition of CO, will cause u precipitate. Heating the solution 

 will also cause a precipitate, for it converts the acid phosphate 

 into neutral phosphate, and by thus liberating free acid acts 

 just as the addition of more acid would do. 



Put some solution of alkali albuminate into two test-tubes ; 

 add solution of sodium phosp ate to one of them, and color 

 them both equally with solution of litmus. 



Neutralize them both with very dilute acetic acid. Very 

 little acid will neutralize the pure solution of albuminate, and 

 the slightest excess will at once turn the litmus red. A 



