CITRIC ACID. 



due, nitrate of ammonia was dissolved, while an 

 insoluble citrate of lead remained behind. The 

 aqueous solution, even when very much concen- 

 trated, was not affected by sulphate of soda, 

 showing that it contained no lead. A portion 

 of it being mixed with some liquid nitrate of 

 lead, and the mixture being evaporated gently 

 to dryness, and the residue being digested in 

 water, a complete solution took place without the 

 appearance of any citrate of lead whatever. 

 This shows that the liquid contained no sensible 

 quantity of citric acid. 



From the preceding experiment it follows, 

 that 9*5 grains of citric acid crystals contain a 

 quantity of citric acid just capable of saturating 

 all the protoxide of lead in 20*75 grains of ni- 

 trate of lead, which amount to exactly 14 grains. 

 The citrate of lead was carefully collected upon 

 a double filter, well washed, and dried, first in 

 the open air, and then in a temperature not ex- 

 ceeding 150 its weight was 21 '25 grains. Now, 

 of this weight, 1 4 grains were protoxide of lead ; 

 the remainder must be citric acid. Thus citrate 

 of lead, dried in 150, is a compound of 



Citric acid . . 7'25 

 Protoxide of lead . 14 



21-25 



This citrate being neutral, and 1 i being the ato- 



9 



