MANUAL OF GENEEAL AGEICULTUEE. 35 



ings to test for calcium. To the residue on the filter add 

 a few drops of hydrochloric acid, and to the liquid that 

 passes through add a drop of potassium sulpho-cyanate 

 solution. A red color proves iron. Heat to boiling the 

 filtrate saved to test for calcium and add 5 c.c. ammo- 

 nium oxalate solution. A milky white precipitate shows 

 calcium in the ash. Filter and wash as above and divide 

 the filtrate and washings into two parts. To one part add 

 slowly drop by drop 5 c.c. sodium phosphate solution. 

 Add 5 c.c. strong ammonia. A white precipitate forming 

 on standing (immediately if there is much magnesium) 

 proves magnesium a constituent of the plant ash. Place 

 the remaining half of the above solution in an evaporat- 

 ing dish. Evaporate to dryness and heat to a dull redness 

 if possible, or till white vapors no longer come off. Cool 

 and add to the residue a drop or two of hydrochloric acid. 

 Heat a platinum wire in a colorless gas flame till it gives no 

 yellow color to the flame. Dip the wire into the residue 

 and again heat it in the colorless flame. A bright yellow 

 color imparted to the flame proves sodium. Repeat the 

 above platinum wire test, observing it through a dark 

 blue glass or a blue bottle that will shut out the yellow 

 color. A violet color, visible only through the blue glass, 

 proves potassium to be in the ash. 



To a fresh portion of about half a gram of plant ash 

 add 5 c.c. each of distilled water and strong nitric acid. 

 Heat to boiling, add 10 c.c. more of distilled water and 

 filter. Divide the filtrate into three parts. To one part 

 add 2 c.c. silver nitrate solution. A white precipitate, or 

 a milkiness imparted to the solution, proves chlorin in 

 the ash. To the second add 5 c.c. ammonium molybdate 

 solution and heat to blood temperature. Let stand for a 

 while and a yellow precipitate will prove phosphorus in 

 the ash. To the last portion add 2 c.c. barium chlorid 

 solution. A white precipitate or a milkiness proves sul- 

 phur. 



