438 PHOSPHATES. 



2. PROPERTIES. White, insipid, pulverulent, insoluble in water, 

 soluble in nitric and muriatic acids ; applied to no use. 



3. ITS COMPOSITION, after being washed and dried, is, according 

 to Berzelius 



Phosphoric acid, 31.8 100. 



Baryta, - - 68.2 214.46 



100. 



Dr. Henry suggests that if it be constituted of 1 equivalent of acid 

 and 1 of base, its composition will be expressed by 



Phosphoric acid, 28 26.62 100 



Baryta, - - _ 78 73.38 280 



Its equivalent, 106 100.00 



Berzelius, by dissolving baryta in phosphoric acid, and evaporating 

 the solution, obtained acidulous crystals, which, if composed of 2 

 equivalents of acid, =56, and 1 of base, =78 = 1<34 3 and would be 

 a bi-phosphate. From a solution of these crystals, alcohol precipi- 

 tates a bulky white and tasteless substance, which appears to be com- 

 posed of 2 equivalents of base, and 3 of acid, or if we say 1 of the 

 former and l of the latter, it would be called a sesqui-phosphate.* 



PHOSPHATE OF STRONTIA. 



1. FORMATION AND PROPERTIES. Every thing in the last article 

 is applicable to this, except that it is soluble in phosphoric acid, gives 

 a purple flame with charcoal before the blowpipe, is totally decom- 

 posed only, by the sulphuric acid and partially by the nitric and mu- 

 riatic acids. It is fusible by the blowpipe, into a white enamel ; it 

 is soluble in 2000 parts of water. 



2. COMPOSITION. Acid, 36.565, base, 63.435 = 100.00. 



Dr. Henry remarks, that " if a true binary compound, it should 

 consist of very nearly 65 base, -f- 35 acid ; and that there is a bi- 

 phosphate consisting of 2 atoms of acid, 1 atom of base, and 2 of 

 water." 



PHOSPHATE OF MAGNESIA. 



1. PREPARATION. 



By digesting phosphoric acid on magnesia or the carbonate. 



By mixing equal quantities of the concentrated solutions of 

 sulphate of magnesia and phosphate of soda ; in a few hours, crys- 

 tals of phosphate of magnesia are formed. 



. 



(a.) 

 (6.) 



* Henry, Vol. I, p. 605. See Berzelius on two sub-phosphates, Ann. of Phi!. 

 XV, 277. 



