GASTRIC JUICE. 119 



2. To sodium formiate solution add a little ferric 

 chloride. The same effect will appear as with an 

 acetate. 



3. Heat sodium formiate with mercuric chloride 

 solution. A precipitate at first of mercurous chloride 

 and finally of metallic mercury will appear. 



4. Add silver nitrate solution and heat. Metallic 

 silver will be deposited as a black powder or a mirror- 

 like coating. 



5. Heat a formiate with dilute sulphuric acid. 

 Formic acid, recognized by its odour, will be set free. 



6. Heat a formiate with sulphuric acid and alcohol. 

 Formic ether, of a peculiar pleasant odour, will be 

 evolved. 



7. Heat a formiate in powder with concentrated 

 sulphuric acid : carbonic oxyde will be given off, 

 and will burn with a blue flame. The mixture will 

 not blacken. 



Gastric juice. 1. Gastric juice, obtained through a 

 gastric fistula or by means of the stomach pump or 

 gastric syphon, must be filtered and examined as 

 follows : 



2. Boil ; no precipitate will be formed. Test the 

 reaction with litmus ; the reaction is acid. Notice 

 taste, smell, and appearance. 



3. Add alcohol of 90% strength, collect the preci- 

 pitate of pepsine (see pepsine). 



4. Distil some gastric juice. The first distillate will 

 be acid, but will give no precipitate with silver nitrate. 



