440 PHYSIOLOGICAL CHEMISTRY. 



tones are to be looked for. Syntonin : The gastric filtrate is exactly 

 neutralized, whereupon a cloudiness or precipitate is formed, which 

 is soluble both in alkalies and in acids. Albumoses : These are pre- 

 cipitated by a saturated solution of ammonium sulphate, while pep- 

 tones remain in solution. Peptones: These are recognized by the 

 biuret-test. The juice is rendered strongly alkaline with potassium 

 hydroxide and a few drops of a cupric sulphate solution (1 in 1000) 

 are added. A red color indicates the presence of peptones. 



In the gastric contents, an hour after an ordinary test-meal, there 

 is usually a large quantity of albumoses and a smaller amount of 

 peptone. A large quantity of syntonin and a weak biuret reaction 

 indicate a weakened proteid digestion and, therefore, a lessened 

 secretion of pepsin and hydrochloric acid. 



j. Detection of carbohydrates. Starch is recognized by the blue 

 color produced by iodine solution (1 iodine, 2 potassium iodide, 100 

 water). The reaction is less marked in proportion to the amount of 

 starch converted into dextrin and sugar. 



Ei-yihrodextrin gives a mahogany-brown color, and achroodextrin 

 remains unchanged by the iodine solution. In strongly acid gastric 

 contents erythrodextrin is found, while in cases in which hydrochloric 

 acid is absent achroodextrin is almost exclusively present. In as 

 much as sugar is present in the test-meal itself, it is useless to test 

 for this substance. 



Bile, secreted by the liver, is a thin, transparent liquid of a golden- 

 yellow color, and a specific gravity of 1.020 ; it has a very bitter taste 

 and an alkaline reaction ; it varies widely in composition, the total 

 solids ranging from 9 to 17 per cent., being always highest after a 

 meal ; its composition, moreover, is highly complex ; the following is 

 an average of five analyses of bile from subjects with healthy livers : 



Water . . 91.68 per cent. 



Mucus pigment . 1.29 " 



Taurocholate of sodium 0.87 " 



Glycocholate of sodium 3.03 " 



Fat 0.73 " 



Soaps 1.39 " 



Cholesterin 35 " 



Lecithin 53 " 



Bile obtained after death is of a brownish-yellow color ; freed from 

 mucus it will remain undecomposed for an almost indefinite period. 

 The mucus may be separated by the addition of diluted alcohol and 

 subsequent filtration. 



