82 CLINICAL MICROSCOPY AND DIAGNOSIS. 



Uffelmann's reagent. 3 drops of saturated aqueous 

 solution of the perchloride of iron are mixed with 3 

 drops of pure carbolic acid, and water added till an 

 amethyst blue solution is obtained. 



Decinormal sodium hydrate solution. Contains 4 

 grammes of Na OH in a litre of water. 1 cc. of the deci- 

 normal solution neutralizes .00,365 grammes of HC1. 



The chemical tests are applied to the filtrate, one- 

 half of the contents being filtered. 



(a) Determine the acidity with litmus paper. 



Acidity may be due to HOI free or combined, to 

 acid salts, or to the presence of such fermentative acids 

 as lactic, acetic or butyric. 



(6) If acid, determine the total acidity by placing 

 5 cc. of the filtered contents in a capsule, adding one or 

 two drops of phenolphthalein solution, and then care- 

 fully adding from a burette, decinormal sodic hydrate 

 till completely neutralized. This will be indicated 

 when no further intensification of the red color occurs, 

 on the addition of more sodic hydrate. Normally from 

 40 to 65 cc. of the decinormal sodic hydrate solution are 

 required to neutralize 100 cc. of the gastric contents. 



(c) If acid, is the acidity due to free acids or acid 

 salts. To determine this add a drop of the gastric con- 

 tents to a drop of the Congo red solution. If free acids 

 are present an azure blue coloration appears. 



(d) If free acid is present, determine if free HCl 

 exists. 



(1) To a drop of the filtrate in a porcelain capsule 

 add a drop of Gunzburg's phloroglucin-vanillin solu- 



