Mr. Maddrell on the Metaphosphates. 329 



pitated (with the proper precautions) by a salt of magnesia 

 and estimated accordingly. 



Found. Atom. Reckoned, 

 grm. Per cent. 

 1-887 substance gave 1-157 2MgO, PO5 = -424 MgO = 22-47 MgO = 22-453 

 2-307 ... =1-46 PO5 = 77-424 PO5 =77-547 



99-894 100-000 



Formula, MgO, PO5. 



Metaphosjyhate of Potash. — This salt was obtained by ig- 

 niting strongly together equal parts of chlorate of potash and 

 phosphoric acid (of a syrupy consistence), and by digesting the 

 mass in water to separate the soluble part fi-om the insoluble. 

 It is an anhydrous compound, nearly insoluble in water, but 

 soluble in diluted as well as concentrated acids. The acetic 

 solution gives a white precipitate with nitrate of silver. This 

 insoluble compound is decomposed on being treated with so- 

 lutions of nitrate of silver, acetate of lead, and chloride of 

 bai'ium, into the metaphosphates of these metallic oxides. 



This compound was dissolved in acetic acid, diluted with 

 water, and the PO5 in the solution precipitated by acetate of 

 lead, and the excess of lead in the liltered solution by sul- 

 phuretted hydrogen. The solution containing potash was 

 then evaporated, and the potash determined as nitrate. 



Found. Atom. Reckoned. 

 1-468 grm. substance gave 1-25 KO, N05 = -582 K0= 39-645 KO = 39-8 

 PO5 estimated as loss = 60-355 PO5 = 60-2 

 100-000 loFo 



Formula, KO, PO5. 



Metaphosjihate of Soda was obtained by igniting strongly 

 together equal parts of nitrate of potash and phosphoric acid 

 (of a syrupy consistence), and by digesting in water to sepa- 

 rate the soluble from the insoluble part. It is an anhydrous 

 compound, nearly insoluble in water, but soluble in diluted 

 and concentrated acids. The solution in acetic acid gives a 

 white precipitate with nitrate of silver ; it is also decomposed 

 on being treated with the same salts as the salt of potash. 

 This salt was dissolved in acetic acid, diluted with water, and 

 the PO5 precipitated in the solution (with proper precautions) 

 by a salt of magnesia. 



Found. Atom. Reckoned. 

 •943gnn. substance gave 1-042 MgO, P05 = -659 P05 = 09-883 PO5 =69-537 

 NaO estimated as loss = 30-117 NaO =30-463 

 100-000 100-000 



Formula, NaO, PO5. 



