PHOSPHORUS AND ITS COMPOUNDS 95 



Experiment //. In a beaker on a sand-bath, dissolve l / 2 gram 

 of bone-ash in 10 cc. dil. HNO 3 -f 20 cc. H 2 O ; filter, and to the fil- 

 trate, while still warm, add 5 cc. ammonium molybdate, and then 

 stir. Observe the precipitate, which is a compound of phosphoric 

 acid, ammonium, and molybdenum. 



Questions, (i) What was the solvent of the phosphoric acid? 

 {2) Why was the solution boiled and filtered? (3) Describe the 

 color and properties of the precipitate. 



Experiment 18. Dissolve % gram of sodium phosphate in 

 10 cc. distilled water, then add 10 cc. of a solution containing I f 2 

 jjram CaCl 2 . Observe the result. Write the reaction. Repeat this 

 experiment, using A1C1 3 or alum in place of CaCl 2 . 



no. Compounds of Phosphorus. Phosphorus forms 

 a large number of compounds, as phosphates, metaphos- 

 phates, and pyrophosphates. It also combines with H, 

 Cl, and I. With H it forms PH 3 , phosphine, an analo- 

 gous compound of NH 3 . Phosphorus also enters into 

 combination with C, H, N, O, and S, forming complex 

 organic compounds, as nucleated proteids and lecithin. 

 It is an element which has a wide range of combinations. 



in. Importance of Phosphorus and Its Compounds. 



The compounds of phosphorus, particularly the phos- 

 phates, are important in plant development, being essen- 

 tial forms of mineral food required for crop growth. 

 Agriculturally considered, phosphorus is one of the most 

 important of the elements. It is stored up in the seeds of 

 grains, and in combination with the elements which form 

 the organic compounds of plants, it takes an important 

 part in animal nutrition. Compounds of phosphorus are 

 used in the manufacture of matches, and as poison for in- 

 . sects. Phosphorus forms a large number of compounds 



