EXAMINATION OF BLOOD. 61 



in the cold, and on heating gives a flocculent precipitate. 

 The greater the amount of salt in the albumin solution the 

 less is the coagulation on heating dependent upon the reac- 

 tion of the fluid; the smaller the amount of salt the nearer 

 must the reaction be to neutral or faintly acid in order that 

 coagulation should take place on heating. 



3. Add nitric acid to a small portion of the solution: a 

 precipitate forms at first, which disappears on shaking, then 

 on the addition of more nitric acid a permanent precipitate is 

 formed, which does not dissolve on heating, but turns yellow 

 owing to the formation of the so-called xanthoprotein. 



4. If we add glacial acetic acid to a small portion of the 

 solution and heat, acid albumin (acid albuminate) results. 

 Cool and add caustic soda solution. While the reaction is 

 still acid a precipitate of acid albumin forms, soluble in an 

 excess of caustic soda. 



5. Heat a little of the solution with half its volume of 

 caustic soda solution. Alkali albuminate is formed. Cool 

 and neutralize with dilute sulphuric or acetic acid. Albu- 

 minate is precipitated, partially soluble on heating with an 

 excess of the reagent. 



6. If we add copper sulphate solution to some of the dilute 

 blood-serum, a bluish-white precipitate of copper albuminate 

 results, which dissolves on the addition of caustic soda solu- 

 tion to a deep-blue fluid. (The salts of the other heavy 

 metals also as a rule give precipitates.) 



7. Add some mercuric chloride solution: heavy white 

 precipitate insoluble in an excess of the precipitating reagent, 

 but soluble in concentrated sodium chloride solution. 



8. If we add to some of the solution a few drops of nitric 

 acid till a permanent precipitate is formed and then add 

 absolute alcohol until the volume of the mixture has been 

 doubled, the greater part of the precipitate dissolves (dis- 

 tinction from egg-albumin). 



