1821.] Strontian, Lime, Magnesia j Phosphoric Acid, S^c. 11 



merits which I am now going to relate will leave no doubts on 

 the subject in the mind of any practical chemist. I do not 

 know how Berzehus has deceived himself; but that he labouredL' 

 under some deception or other will not admit of a doubt. 



It would be tiresome and perfectly unnecessary to relate the 

 numerous experiments which I made to determine the weight of 

 an atom of phosphoric acid. I shall confine myself to those 

 which answered the object that I had in view. 



If Berzelius's opinion respecting the weight of an atom of 

 phosphoric acid be true, then anhydrous phosphate of soda is 

 composed of 



Phosphoric acid 4*5 



Soda 4-0 



Phosphate of soda. 8*5 



We have seen in a former paper that dry nitrate of lead is 

 composed of 



Nitric acid 6*75 



Protoxide of lead 14-00 



Nitrate of lead 20-75 



To put Berzehus's analyses to the test of experiment, I 

 exposed a quantity of pure crystallized phosphate of soda to a 

 red heat, and kept it in fusion for half an hour. 8*5 grs. of this 

 anhydrous salt and 20-75 grs. of dry nitrate of lead were respec- 

 tively dissolved in separate portions of distilled water, and the 

 solutions were intimately mixed together. After the phosphate 

 of lead had precipitated, a portion of the clear liquid was drawn 

 off and examined. ' It yielded a white precipitate when mixed 

 with nitrate of lead and with muriate of lime. Hence it obviously^ 

 contained phosphoric acid in solution. Hence the oxide of lead 

 in 20*75 grs. of nitrate of lead is not capable of neutrahsing all 

 the phosphoric acid in 8-5 grs. of anhydrous phosphate of soda. 

 It follows from this that Berzelius's statement of the composition 

 of phosphate of soda is incorrect. 



If my own opinion respecting the composition of phosphoric 

 acid be true, its weight must be 3-5, and anhydrous phosphate^ 

 of soda must be composed of 



Phosphoric acid 3*5 



Soda 4-0 



Phosphate of soda 7*5 



To verify this opinion, 7-5 grs. of anhydrous phosphate of 

 soda and 20-75 grs. of dry nitrate of lead were dissolved respec- 

 tively in separate portions of distilled water, and the solutions 

 mixed together. After the phosphate of lead had subsided, a 



