BY DR. LAUDER BRUNTO^ 4^3 



proportion of inorganic salts, but there is no way known of 

 removing them without completely altering its constitution. 



4. Preservation of Albumin. If kept in solution, 

 albumin will quickly decompose, and it is inconvenient to 

 prepare it from eggs every time that a solution is required. 

 It may, however, be preserved for a long while by evaporating 

 the solution to dryness at 40 C. (see App. 208). The dry 

 albumin forms a yellowish transparent glassy substance, which 

 may be kept in a stoppered bottle, and dissolved as required. 



5. Serum Albumin. Preparation : Add very dilute 

 acetic acid, drop by drop, to serum of blood or hydrocele fluid, 

 stirring it constant!}' all the time, till a flocculent precipitate 

 is produced. Filter. Add a dilute solution of sodium carbo- 

 nate to the filtrate till it is nearly neutralized ; evaporate it to 

 a small bulk at 40 C. ; separate the salts by diffusion, and 

 evaporate the solution at 40 C. to dryness, in the same way 

 as directed for egg albumin. It still contains small quantities 

 of salts, but it is almost impossible to separate them from it. 



6. Differences between Serum Albumin and Egg 

 Albumin. Serum albumin agrees with egg albumin in most 

 of its characters, but it differs from it in the following re- 

 spects : 



1. Its solutions are not coagulated by ether. 

 N 2. It is more easily precipitated from its solution by hydro- 

 chloric acid. 



\. 3. It dissolves more readily in concentrated nitric or hj-dro- 

 chloric acid, and the precipitate thrown down by dilution from 

 the solutions in these acids, as well as that thrown down by 

 these acids from solutions in other menstrua, is readil}' and 

 completely soluble in the concentrated acids, while the pre- 

 cipitate of egg albumin is not. 



When injected under the skin of an animal it does not 

 appear in the urine, while egg albumin does so either when 

 injected under the skin or introduced in large quantities into 

 the stomach or rectum (Stockvis). 



* 7. Solubility of Dry Albumin. In testing the solu- 

 bility of albumin or other substances to be afterwards men- 

 tioned, they ouglftt first to be pulverized and then agitated or 

 stirred .vitii the liquid. It' the powder rung \\\\.$ Tru"""* 8 , these 

 ought to be broken up with a glass stirring rod ; this may be 

 don,e much more easily if the rod is very thick or has a bulb- 

 ous end. 



If simple agrtfrtion or heat suffices to dissolve a substance, 

 it may be placcu in a test-tube, but if it requires stirring it 

 should be put in a test-glass (as the rod is apt to break the 

 tube), and afterwards transferred to a tube if heat is to be 

 Applied. 



The fact of a substance being soluble in a liquid is ascer- 



