TOPPER'S METHOD OF GASTRIC ANALYSIS 225 



drop by drop a 2 per cent sodium carbonate solution until a light- 

 pink color is produced. 



(e) To tubes 1, 2, 3, and 4 add 0.5 c.c. of casein solution. Tube 

 5 must receive 1 c.c. of casein solution, since it contains 1 c.c. 

 of the diluted gastric contents. For the casein solution, dissolve 

 0.4 gm. of casein in 40 c.c. of N/10 NaOH. Add 130 c.c. of dis- 

 tilled water, then 30 c.c. of N/10 HC1. This leaves the solution 

 alkaline to the extent of 10 c.c. of N/10 NaOH, minus about 3 c.c. 

 neutralized by the casein. 



(/) Incubate for five hours at 40 C. 



(g) Precipitate the undigested casein by dropwise addition of 

 a solution of the following composition: glacial acetic acid 1 c.c.; 

 alcohol (95 per cent) 50 c.c.; distilled water 50 c.c. The tubes in 

 which digestion has been complete remain clear; others become 

 turbid. 



(h) The tryptic values are expressed in terms of dilution. 

 Thus, complete digestion in tube 3 (a dilution of 1/4) shows four 

 times the tryptic power of undiluted gastric juice; taken as a 

 standard as 1, therefore, its tryptic value is 4. 



(i) Controls of boiled gastric contents plus casein solution, 

 and of distilled water plus casein solution, treated as above stated, 

 must show no digestion, and become turbid on addition of the 

 precipitating solution. 



TOPPER'S METHOD OF GASTRIC ANALYSIS l 



This method is much less elaborate than many others but is 

 sufficiently accurate for ordinary clinical purposes. The method 

 embraces the volumetric determination of (1) total acidity, (2) 

 free acidity (organic and inorganic), and (3) free hydrochloric acid, 

 and the subsequent calculation of (4) combined acidity and (5) 

 acidity due to organic acids and acid salts, from the data thus 

 obtained. 



Procedure. Feed the Ewald test meal as directed on page 217. 

 At the end of one hour remove the entire stomach contents and 

 analyze as directed below. This method of procedure is less 

 accurate than the Fractional Method (see page 215). Measure the 

 volume of the gastric contents, strain it through cheesecloth and 

 1 Hawk: Practical Physiological Chemistry, Sixth Edition, 1918. 



