172 On Trtbaeic Phosphoric Acid. 



tain analyses of phosphates of baryta and lead, that 1"" phos- 

 phorus combined with 122.2 oxygen in phosphoric acid, and that 

 l 1 phosphoric acid, containing .v> parts of oxygen, saturated 

 parts of oxygen in a base, that therefore the compo- 

 sition of phosphoric acid was PO\ Aiter many experiments 

 and a great «K:il of reflection, however, he came t<> the con- 

 clusion that the proportion was a different one. About this 

 time be was notified by Thomson (Aim. of Phil, id 306) that 

 in contradiction to Dulong he had found L63.4 of to LOO of P 

 in phosphoric acid, and that he had prepared six different 

 phosphates of lime containing to 5 eq. of phosphoric acid, 1, 

 2, ;;. l. 5 and 6 eq. of lime. As, however, certain of his 

 salts were prepared by evaporation ami ignition of weighed 

 quantities <>t' phosphoric acid and lime salt, and others cannot 

 l.c prepared according to his prescription, we will nol go further 

 into tin- details lie gives. IK- mentions, however, the fact, that 

 phosphate of lime ignited with chloride of calcium drives oil 

 chlorine, which Berzelius found to be true. Berzelius divides his 



,v int<» six parts, ami it being of a very important nature. I 

 may be allowed to enter at some length into its results : 



1 . ( )n the composition of phosphates, 



2. ( »m the composition of phosphoric acid. 

 ::. ( )n the composition of phosphorous acid. 

 4. On the composil ion of phosphites. 



.">. < >n the condition in which phosphorus is contained in 

 metallic phosphides. 



6. On the weight of a volume or molecule of phosphorus, 

 and other kindred subjects. 



1. For those investigations the precipitates were produced 

 by phosphate of ammonia, which was prepared by supersatu- 

 ng pure phosphoric acid with pure ammonia, ami evapo- 

 rating until litmus paper was only very slightly reddened. Ii 

 found here, that sali 1 - of lend and baryta enter readily into 

 the composition of the precipitated phosphates, ami only after 

 • deal of inquiry Berzelius devised mean- to avoid this. 



