488 PEACTICAL PHYSIOLOGY 



II. Eeaction. 



A. Acid may be due to : 



on g red test (p- 220 >- ;'" x 



If due to free acid, ascertain whether this be 



1. a mineral acid or ) apply Gunsberg's and the tropaeolin 



2. an organic acid / test (p. 221). 



If due to an organic acid, apply Uffelmann's test for lactic acid. 



B. Alkaline test for carbonic acid (effervescence with mineral acid), 



ammonia (smell, etc.), caustic alkali. 



The following Chemical Tests should now be applied to Suitable 

 Quantities of the Solution. 



I. For Carbohydrates. 



1. Apply Trommer's test. 



A. Positive indicates monosaccharides, lactose, or maltose. 



B. Negative, but complete solution of cupric hydrate obtained 



on adding caustic alkalie, indicates cane sugar. Confirm 

 for this by boiling some of the solution with a mineral 

 acid for a minute or so, and applying Trommer's test to 

 the product reduction indicates cane sugar. The 

 original solution will also taste sweet. 



G. Negative, and no solution of cupric hydrate. Absence of 

 monosaccharides and disaccharides. 



2. Add Iodine Solution. 



(a) a blue colour which disappears on heating, and returns on 



cooling indicates starch. 



(b) a port-wine colour which disappears on heating, and 



returns on cooling indicates dextrin or glycogen. Confirm 

 for polysaccharides by heating some of the original fluid 

 for about fifteen minutes with a mineral acid, and testing 

 for sugar in the hydrolysed fluid. 



To distinguish between Starch, Glycogen and Dextrin. Shake 

 up some of the original powder with cold water and filter. By 

 this treatment glycogen and dextrin will dissolve, starch will 

 not. Wash the filter paper thoroughly with water, then add 

 a drop of Iodine solution a blue stain indicates starch. Add 

 Iodine solution to the filtrate a red colour indicates dextrin 

 or glycogen ; if the former body be present the filtrate is 

 clear, opalescent if the latter. 





