Put all three into a warm water bath at about the tempera- 

 ture of the body (36-40 C.)- 



17. After ten minutes remove test tube A and boil. The 

 proteid is no longer coagulated by heat, having been con- 

 verted into alkali-albumin. After cooling color with litmus 

 solution, and neutralize with 0.1% acid. At the neutral 

 point a precipitate is formed, which is soluble in excess of 

 either acid or alkali. 



18. Next remove B. This also now contains alkali-albu- 

 min. Add to it a few drops of a sodium pho,sphate solution, 

 color with litmus, and neutralize as before. Note that the 

 alkali-albumin now requires more acid for its precipitation 

 than in A, the acid which is first added converting the 

 sodium phosphate into acid sodium phosphate. 



19. Now remove C from the bath. Boil it. Again there 

 is no coagulation, the proteid having been converted into 

 acid-albumin or syntonin. After cooling color with litmus 

 and neutralize with 0.1% alkali. At the neutral point a 

 precipitate is formed .soluble in exce.ss of acid or alkali. 

 (Acid-albumin is formed more slowly than alkali-albumin, 

 so it is well to take plenty of time). 



20. Metallic albuminates. Add to separate tubes of albu- 

 min solution, a crystal each of copper sulphate, .silver ni- 

 trate and a small amount of mercuric chloride. In each of 

 the three tubes metallic albuminates will be precipitated. 



21. Albuminoids. — Albuminoids consist of a number of 

 bodies which, in their general characters and elementary 

 composition resemble proteids, but differ from them in many 

 respects. They are amorphous. Some of them contain 

 sulphur, and others do not. The decomposition-products 

 resemble the decomposition-products of proteids. 



Gelatin is obtained by the prolonged boiling of connective 

 tis.sues, for example, tendon, ligaments, bone and from the 

 substance " Collagen" of which fibrous tissue is said to 

 exist. 



