170 On Tribasio Phosphoric Add. 



in the year L810 (Gilbert's Aim. vol. 37) the above-men- 

 tioned essay of Berzelius, in which, after a careful study 



and comparia f many analyses, he found: that when two 



oxydized substances combine, the oxygen of the electro-nega- 

 tive complex i> always a multiple in a whole number of the 

 oxygen of the electro-positive complex. To arrive at this conclu- 

 sion a great number of reliable and good analyses were required, 

 and. in ordm- to make them, difficulties were encountered that 



only Kc appreciated when one considers the imperfect 



methods of separation and the few expedients then at hand. 

 Berzelius undertook this task, and analvzed in the course of Ids 

 researches many compounds of phosphoric acid, especially with 

 oxyd of lead and baryta, in which phosphoric acid was deter- 

 mined by loss. lie found the proportion of the oxygen in the 

 acid to that in the base to he as 2:1, taking the constitution of 

 phosphoric acid as it was taken at that time. 



Phosphorus had been the first combustible body the capacity 

 of which for oxygen was determined by chemists, a thjng that, 

 in this case appeared very easy, hut in fact offered considerable 

 difficult^ . 



Lampadius fin his hand-book of chemical analysis of min- 

 eral substances, 1 798) had found the praportions of phospho- 

 rus to oxygen in phosphoric acid to he as 



100: l*»<i. 



Lavoisier had found it to he as 



100 : 1 :. J . 



Davy (in his miscellaneous researches concerning the com- 

 pounds of phosphorus, 1810) had found it to be as 



100: L53. 

 land taking in phosphoric acid twice as much oxygen as in 



phosphorOUS acid i. 



Thenard (in his remarks on phosphorus, 1*1 \) had found it to 



he OS 



LOO : 1 1" 



