24 



notes why no action has occurred in certain of the tubes. 

 Test-tubes C and C are to be plugged with cotton and 

 reserved for later examination. 



102. The following tubes are to be prepared exactly as C 

 but omitting the fibrin. In the first tube a very small piece 

 of cooked meat ; in the second a crumb of bread ; in the 

 third a bit of boiled potato ; in the fourth a small piece of 

 dried albumin ; in the fifth add a small piece of butter ; in 

 the sixth, i cc. of milk diluted with 5 cc. of distilled water ; 

 in the seventh test-tube, small amounts of all the above sub- 

 stances. These tubes, also, are to remain in the water bath 

 at 40" C. , and examined later for any changes. 



IX. 



103. The contents of tubes C and C are to be divided, each 

 tube, into 4 parts, 3 of which are to be used in the following 

 tests, and the other part to be held in reserve. 



104. Color one portion of the fluid with the litmus solu- 

 tion and neutralize with dilute caustic potash. At the neutral 

 zone a precipitate will appear indicating acid-albumin (syn- 

 tonin or parapeptone). 



105. To another portion add sodium chloride and a few 

 drops of nitric acid. A precipitate should appear which is 

 dissolved on heating, but reappears on cooling, indicating 

 the presence of albumose (proteose or propeptone). Albu- 

 mose like peptone is soluble in water, and gives a biuret 

 reaction. 



106. Another test for albumose is to add to the solution 

 enough neutral ammonium sulphate to saturate it. This 

 brings down the albumoses in the form of a white precipi- 

 tate. 



107. Peptones behave differently from the native proteids 

 in the copper sulphate and caustic potash test, if only a trace 



