on Phosphoric Acid. 15 
Phosphate of ammonia. 
The phosphoric acid combines with ammo- 
nia in circumstances nearly similar to those of 
soda; but I have not ascertained the precise 
distinctions of the compounds. If ammonia, 
or carbonate of ammonia be added to super- 
phosphate of lime by degrees till the liquid 
indicates neutrality by the colour test, it will 
be found when 46 acid by weight are combin- 
ed with 6 of ammonia, or two.atoms of acid to 
one of ammonia, which may be called a bi- 
phosphate (or if we state the atom of ammo- 
nia at 12 it will be a quadriphosphate); no 
doubt a simple phosphate, and perhaps a sub- 
phosphate, may exist. 
I have not yet examined the triple salts, 
said to be formed by some of the alkalies 
and earths with phosphate of ammonia. 
General remarks on the phosphates. 
It is well known that nitric and muriatiec 
acid dissolve the phosphates, and that they are 
again precipitated unaltered by lime water 
and ammonia, I imagined this to be a pro- 
per example of solution and not of decom- 
position; and this notion appears to me to be 
generally entertained, According to this idea 
sulphuric acid decomposes the phosphates, but 
nitric and other acids only dissolve them. 
find however this notion not correct. Nitric 
