MEMOIRS 
OF THE 
LITERARY AND PHILOSOPHICAL SOCIETY 
Manchester. 
EXPERIMENTS AND OBSERVATIONS 
PHOSPHORIC ACID; 
AND ON THE SALTS DENOMINATED PHOSPHATES. 
BY JOHN DALTON. 
(Read January 22, 1813.) 
= Poe” 
In order to obtain pure phosphoric acid, it 
has generally been recommended to oxidize 
phosphorus by heated nitric acid. This pro- 
cess is both tedious and expensive; an ounce 
of phosphorus would require a pound of ni- 
tric acid, and the produce would be about 3 
ounces of phosphoric acid, the elements of 
which would cost 7 or 8 shillings at least, and 
the labour attending it would perhaps cost as 
much more; so that the pure phosphoric 
acid could hardly be retailed under five shil- 
VOL. II. A 
