SECRETION DIGESTION ABSORPTION. 



tion with distilled water. This precipitate is redissolved in the 

 sodium-chlorid solution as given above. 



D, proteose. This may be prepared by digesting a small quan- 

 tity of fibrin with o.2-per-cent HC1 and a little commercial pep- 

 sin, at 38 C., just to the point of solution of the fibrin and no more. 

 Neutralize carefully with dilute NaOH, heat to boiling, and filter. 

 Witte's peptone may be used, since it consists chiefly of albumoses. 



E, peptone. Savory & Moore's preparation is used. 



Place a small quantity of each of the above solutions in test- 

 tubes and immerse in a water-bath heated to 65 C. Gradually 

 raise the temperature of the bath to 100 C., noting observations 

 at every 5 rise in temperature. 



Are all of these solutions coagulated by heat ? In those in which 

 coagulation does occur, is the coagulating point the same ? 



(b) Nitric-acid Ring Test. Place a small quantity of HNO 3 in 

 a test-tube. With a glass tube of small calibre draw up some of 

 solution A into the tube, and with the finger firmly pressed over the 

 other end introduce the end containing the solution into the acid. 

 Remove the finger. If the acid level is slightly higher than the 

 level of the liquid in the tube, some of the acid will be drawn up 

 into the glass tube containing the solution to be tested. Is there 

 any ring of precipitation formed where the two liquids come in 

 contact ? Repeat this test for the other proteid solutions and re- 

 cord results. 



(c) Xanthoproteic Reaction. Add an excess of concentrated 

 nitric acid to a little of each of the above tested solutions and heat 

 to boiling. A yellow color is produced. Neutralize and make the 

 solutions alkaline with sodium hydrate or ammonia. The color 

 changes to an orange red. 



(d) Biuret Test. Make the solutions of the proteids to be tested 

 alkaline with sodium hydrate. Add a few drops of a dilute cupric- 

 sulphate solution. Be careful not to add an excess of the copper 

 solution, since this may give a test in the absence of proteid. A 

 blue-purple or violet color results. 



(e) Millon's Test. Test each of the solutions with Millon's 



