10 Experiments and Observations 
pence in procuring this would not be more 
than 4, or ,4, of what the pure phosphoric 
acid would cost. 
When lime water is gradually added to 
superphosphate of lime no precipitate ensues 
till the salt is reduced below a triphosphate. 
So that a superphosphate consisting of three 
atoms of acid and one of lime isstill a solu- 
ble salt. But what is very remarkable I have 
not been able to procure a biphosphate of 
lime either in the solid or liquid form; for, 
when lime water is added toa triphosphate in 
such proportion as to reduce it to a biphos- 
phate, simple phosphate is precipitated and 
triphosphate remains in solution. 
If a triphosphate solution be evaporated to 
dryness in a moderate heat and then dissolved 
in water again, simple phosphate of lime 
precipitates, and there remains a quadriphos- 
phate in solution. 
If instead of lime water we keep adding 
gradually, recently precipitated and moist 
phosphate of lime to superphosphate, it is 
instantly dissolved till at length the solution 
is reduced to triphosphate. 
If a drop of sulphuric acid be added to a 
triphosphate or quadriphosphate of lime, the — 
liquor becomes turbid and deposits sulphate 
of lime. I have not pursued the distinctions 
