33 
2 4 '8 per cent of water, and no more Sulphurous Acid in 
proportion to Lime than the above described powder. 
The solution is also precipitated by a current of an 
indifferent gas like Hydrogen. The analysis of the precipi- 
tate gave figures from which no simple formula can be 
calculated. The amount of Phosphoric Acid in proportion to 
the Lime is greater than that corresponding to Tribasic 
Phosphate, and the amount of Sulphurous Acid is much 
less than that of the precipitate obtained by boiling. In 
accordance with the foregoing, the solution after treatment 
with Hydrogen Gas, was found to contain less Phosphoric 
Acid in proportion to the Lime than before. 
Under reduced pressure the Phosphate solution boils 
easier and the separation of the precipitate takes place more 
readily. This precipitate contains less Sulphurous Acid and 
more water than corresponds to the formula 3CaO, P0 5 , S0 2 , 
2HO. 
I experienced so much difficulty in preparing pure Tri- 
basic Phosphate of Lime, that I was obliged to use for most 
of my experiments the Phosphate offered by nature in Bones 
and Bone Ash. 
The Compounds of Phosphate of Lime with Sulphurous 
Acid undoubtedly possess great scientific interest. This 
consideration, as well as the importance they are likely to 
attain for agricultural and sanitary purposes, as they have 
now become articles of commerce, -has induced me to lay 
before you the results obtained so far in my investigation, 
with the prosecution of which I am still occupied. 
