32 PRACTICAL PHYSIOLOGY. [iV. 



(ii.) With the filtrate A. test for phosphoric acid by uranium acetate = 

 yellowish-white precipitate of uranium phosphate (UrO,)HP0 4 . 



(iii.) Calcium, by adding ammonium oxalate Ca 2 C 2 4 4 H.,0. Filter, and 

 when the nitrate is clear and gives no longer a precipitate with ammonium 

 oxalate, make it alkaline with NH 4 HO = after a time crystalline precipitate of 

 ammonio - magnesium phosphate MgNH^POj + GH^O, showing presence of 

 magnesium. 



3. EXAMINATION OF A SOLUTION FOR PEOTEIDS 

 AND CARBOHYDRATES. 



I. Physical Characters. 



(a.) Note colour and transparency. Glycogen solution is 

 opalescent, starch and some proteid solutions less so. 



(b.) Taste. Salt solution may contain globulin. A sweet taste 

 indicates a sugar. 



(c.) Smell. The beef-tea odour of albumose and peptone solution, 

 and the smell of British gum are characteristic. 



(d.) Other characters. Thus a persistent froth is suggestive of 

 an albuminous solution. 



II. Test for proteids by xanthoproteic and Millon's tests. If 

 present : 



1. Test reaction to litmus paper. If acid or alkaline, test for 

 acid- or alkali-albumin, and if either is present, neutralise, and 

 filter off precipitate. Test nitrate for proteoses and peptones as in 

 4 and 5. 



2. If original solution is neutral, acidulate faintly, and boil. A 

 coagulum may consist of native albumin, or globulin, or both. Filter; 

 and test nitrate for proteoses and peptones as in 4 and 5. 



3. Distinguish between albumin and globulin by (a.) dropping 

 solution into water, precipitate indicates globulin, (/>.) saturating 

 solution with Mg!30 4 , precipitate = globulin, but may also contain 

 proto- and hetero-albumose. If precipitate obtained by (/;), filter 

 and boil filtrate, coagulum = native-albumin. Distinguish between 

 egg- and serum-albumin by etheY test. 



4. Add excess of NaHO, then, drop by drop, very dilute CuS0 4 , 

 pink colour indicates proteoses, or peptones, or both. 



5. Separate proteoses from peptones by saturating solution with 

 Am 2 S0 4 . Precipitate = proteoses. Filter ; and to filtrate add large 



