1 62 PHYSIOLOGICAL CHEMISTRY 



solution using tropaeolin O as an indicator, and of an N/ioo ammonia solution 

 using phenolphthalein as an indicator. Note the results and then titrate 10 c.c. 

 portions of both solutions with N/ioo HC1 using alizarin as an indicator. 



3. Mix equal portions of M/i5 potassium dihydrogen phosphate and M/i$ 

 disodium phosphate (see chart). Note that the mixture is practically neutral to 

 litmus. Titrate one 10 c.c. portion of this mixture with N/io KOH, using phe- 

 nolphthalein as an indicator. Titrate another portion with N/io HC1 solution, 

 using methyl orange as an indicator. 



4. Mix equal volumes of N/5 sodium acetate solution and N/5 acetic acid. 

 Note that the mixture is acid to litmus. Titrate one 10 c.c. portion with N/io 

 HC1 using tropaeolin OO as an indicator. Titrate another portion with N/io 

 KOH using phenolphthalein as an indicator. 



THE FRACTIONAL METHOD OF GASTRIC ANALYSIS 



Procedure in Gastric Analysis by the Fractional Method 



1. Introduction of the stomach tube (see pages 162 and 163). 



2. Removal of the residuum (see pages 163 and 164). 



3. Feeding the test meal (see page 164). 



4. Feeding the retention meal (in special cases), see page 164. 



5. Removing samples of stomach contents for analysis (see page 164) . 



6. Examination of the samples for: 



(a) Total acidity (see page 161). 



(b) Free acidity (see page 167). 



(c) Pepsin (see page 168). 



(d) Trypsin (not a routine procedure), see page 171. 



(e) Lactic acid (see page 172). 

 (f)' Occult blood (see page 173). 

 (g) Bile (see page 174). 



(H) Microscopical constituents (see page 175). 



i. Introduction of the Stomach Tube. Whereas the large tube is 

 directly inserted by propulsion, the Rehfuss tube is swallowed in the 

 natural manner and aided by gravity. The tube may be passed in one 

 of three ways, i.e. : (i) lubricated; (2) with aid of fluid; (3) after throat is 

 cocainized. When passed by the first method the tip of the tube, after 

 thorough lubrication with glycerol or liquid petrolatum, is seized between 

 the thumb -and forefinger and placed on the tongue. Then with the 

 aid of the forefinger the tip is pushed backward until it reaches the root 

 of the tongue and is engaged in the oropharynx. Then the patient is 

 encouraged to swallow persistently while the tube is slowly fed into the 

 mouth. After slight discomfort in the pharynx and its passage past the 

 level of the cricoid cartilage, practically no discomfort is felt. This 



