174: On Triba&ic Phosphoric Acid. 



of acids by bases was either to be regarded as false, or the com- 

 position of phosphoric acid was a difFerenl one. 



Berzelins therefore again determined the oxygen in phos- 

 phoric acid, bnt in a way thai had never as yet been tried, 

 namely, by the reduction of certain oxyds in solution with 

 phosphorus. A.fter many and wonderfully invented experi- 

 ments, he found an excellent substance for this purpose in 

 chloride of gold, which gave him to LOO phosphorus L26.99, and 

 1 27 1 of oxygen, the silver salt having given him the number 

 128.17. These determinations and the above-mentioned analy- 

 sis proved therefore the oxygen of the phosphoric acid to be 5, 

 ■\, | paiis of the oxygen of the base, that therefore phosphoric 

 acid had a composition similar to that of nitric acid, and that 

 phosphoric acid probably contained !j of the oxygen in phos- 

 phorous acid. In order to decide this point, he had to ascertain 

 the amount of oxygen in phosphoric acid, but before doing this 

 lie determined once more the oxygen in phosphoric acid by de- 

 composing the highest chloride of phosphorus, and obtained as 

 a result 127.74, which then sustained him in this opinion. 

 :'.. A.8 the highesl chloride of phosphorus had given him 60 



■ 1 results, he U6ed for this determination the lower chloride, 

 and obtained in two analyses 7<i.'. , L' and 77.28. Davy had for- 

 merly found T6.5. The proportion of the 0x3' gen of phosphoric 

 acid to the oxygen of phosphorous acid was also not as •_' : l (as 

 found by Davy) nor as 3 : 2 (as found by Gay Lussac), bul as 

 5:3! 128.16:76.9). 



1 . A- the proportion of oxygen of phosphoric acid to thai of 

 phosphorous acid is as 5 : '■'>. phosphorous acid will have a compo- 

 sition analogous to sulphuric acid, and neul ral phosphites ought 

 to contain .', of oxygen in the base, compared with thai of the 

 acid. Berzeliue found, however, in analyzing the salts of lead 

 and barvta, the oxygen in t he base equal to I of thai of the acid. 

 A.8 the behavior of these two acids presents anomalies and 

 prions to the ride, which may easily be explained in 

 <>t' the phosphorus containing oxygen, an investigation was 



