434 PHOSPHATES. 



PHOSPHATE OF SODA AND AMMONIA. 



1. PREPARATION. By dissolving in a little boiling water, 1 

 equivalent of muriate of ammonia, and 1 of phosphate of soda ; the 

 double phosphate crystallizes as the fluid cools, and muriate of soda 

 remains in solution. 



2. PROPERTIES. 



(a.) Primary form, the oblique rhombic prism ; effloresces, losing 

 ammonia, and passes to the condition of bi-phosphate of soda. 



(6.) Decomposed by heat ; the ammonia and water are dissipated 

 and a very fusible bi-phosphate of soda remains. 



3. COMPOSITION. 1 equivalent phosphate of soda, 60, -{-1 of 

 phosphate of ammonia 45,-f 10* of water in the crystals =90 = 195. 



Remarks. This is the microcosmic salt, in a state of purity. 

 According to Fourcroy, this salt effloresces, loses its ammonia, and 

 passes to the condition of bi-phosphate of soda. It turns tincture of 

 violets green. The ammonia is said to be dissipated by repeated so- 

 lutions and crystallizations. 



PHOSPHATE OF LIME. 



1. DISCOVERY. By Gahn and Scheele, in 1774, who found that 

 hones consist principally of this substance, with some other salts, 

 cemented by gelatine ; it exists in bones, in the proportion of 86 per 

 cent. 



2. PREPARATION. 



(a.) By precipitating lime water, by liquid phosphoric acid 

 (b.) Or, phosphorus burned beneath a bell glass inverted over 

 lime water, becomes phosphoric acid, and precipitates the lime 



!c.) Or, by mingling solutions of phosphate of soda, and muriate 

 ime, adding the muriate lastf 



(df.) Or, we may purify the phosphate of lime of bones or. lix- 

 iviate bone ashes with abundance of hot water, to remove muriate 

 and phosphate of soda, and the carbonate of lime may be dissolved by 

 acetic acid ; or, dissolve the phosphate by muriatic acid and precipi- 

 tate by ammonia ; the phosphate falls without decomposition, and 

 after being dried is pure. J 



3. PROPERTIES. 



(a.} A white powder, never crystallized except as a native mineral, 

 (b.) Insoluble in water, tasteless and inodorous. 

 (c.) Melts by the most intense heat into an opake white enamel, 

 (d.) Unaffected by the air. 



(e.) Formed with water, into a paste, it is made into cupels for 

 ithe assay ers. 



* Mistcherlich quoted by Turner. 



1 Otherwise the .precipitate will have excess of base, and the liquor will be acid. 

 Berzelius. + Fourcroy. 



