32 



99. To another portion add some solution of calcium 

 chloride. A calcium soap is formed which is insoluble in wa- 

 ter. It is this compound which is produced by the aciion of 

 soap on "hard water." Many of the heavy metals give similar 

 compounds. Solutions of lead, iron, copper, etc., may be tried. 



100. To the remainder of the potassium soap solution 

 add sulphuric acid slowly until it is plainly acid to test paper. 

 The fatty acids are set free as insoluble substances, the gly- 

 cerine remaining in solution. Filter out the acids by means 

 of a wet filter paper, through which the acids will not pass. 

 The filtrate contains the glycerine, and must undergo still 

 further treatment before the glycerine can be obtained in a 

 pure form. 



VI 



O 

 EXAMINATION FOR A TEST SOLUTION OF PROTEIDS 



AND CARBOHYDRATES 



101. Note the physical characters of the solution as to 

 color, transparency, odor, and taste. A persistent froth sug- 

 gests an albuminous solution. Filte r the solution if not clear. 

 Divide it into two portions, and follow the outlines below. 

 A. Proteids. 



Test reaction to determine if acid or alkaline. 

 Neutralize. If a precipitate forms it is acid or al- 

 kali albumin. If either is present, filter. 



Pour a few drops of the filtrate into water. A pre- 

 cipitate or turbidity shows globulins, if present. 



Pour remainder of filtrate into excess of water and 

 filter. 



To this filtrate add acetic acid and sodium sulphate 

 and boil. Albumins, if present, are precipitated. If 

 precipitate is formed, filter. 



Test filtrate for gelatin. If present, saturate thor- 

 oughly with ammonium sulphate (crystals) and filter off 

 precipitated gelatin. 



Test filtrate tor peptones. Biuret test (cold). 



