36 



crystals also precipitates the starch but does not affect the 

 dextrins or maltose. 



113. The effect of drug's on salivary action. The follow- 

 ingf may be used : carbolic acid 2 % , saturated aqueous solu- 

 tions of salicylic, benzoic and boric acids, corrosive sublimate 

 1 — 1000, quinine bisulphate 2%, alcohol 50%. Place in each 

 test tube 2 cc. boiled starch 2%, 2 cc. sodium carbonate 5%, 

 1 c^ saliva, 5 cc. of the given drug-. Shake and set in the 

 water bath at 40° C for an hour. The activity of dig-estion 

 may be compared by testing- a small portion of each tube -with 

 the iodine solution, to see if the starch has disappeared ; or 

 another small portion -with Fehling's to see if maltose has 

 formed. A cruder method is to add to each tube an equal 

 volume of 10% caustic soda or potash with a little dilute 

 copper sulphate solution (Trommer's test). The amount of 

 precipitate or depth of color roug-hly corresponds to the amount 

 of digestion. 



114. Bread. Crumble up a small piece of bread in a test- 

 tube and add some cold distilled water until it softens and 

 with slight shaking disintegrates. Divide the mixture into 

 two portions. 



115. Apply a drop of iodine solution : blue color indi- 

 cates starch. <■■ 



116. Apply the xanthoproteic reas^ion to the other portion. 

 Any crumbs that may be in the solution if colored orange 

 would indicate the presence of a proteid. The liquid portion 

 may not show as deep a color, indicating a lesser amount in 

 solution. 



117. Try the above tests hurriedly by dropping a little 

 iodine solution upon the bread. Similarly with the xantho- 

 proteic test by letting a drop of nitric acid fall upon the 

 bread and then a drop of ammonia upon the spot already 

 covered by the nitric acid. 



118. Potato. Boil a small piece of potato in water and 

 let it cool. Divide: the liquid into two parts. 



Test one portion for starch with the iodine solution. 

 Without boiling, the starch might give no reaction as the 

 granules are enclosed in a coating of cellulose. 



119. Apply the xanthoproteic test. Only a faint orange 

 color appears, indicating that very little proteid is present. 



