244 
Monpay, May 287TH, 1855. 
THOMAS ROMNEY ROBINSON, D.D., Present, 
in the Chair. 
Dr. ALpRipGE read a paper on the nature of the precipitate 
which occurs in the preparation of alkaline phosphates. 
‘¢The composition of the precipitate produced by the ad- 
dition of the carbonate of potash, soda, or ammonia, to the acid 
liquor made by digesting dilute sulphuric acid upon bone 
ashes, does not seem to have been very carefully studied by 
chemists. 
‘‘M. Dumas considers this precipitate to be carbonate of 
lime. He says in his ‘ Traité de Chimie appliquée aux Arts,’ 
tome ii. p. 318 :—‘ On lobtient en versant, dans une dissolu- 
tion de phosphate acide de chaux du carbonate de soude en dis- 
solution, jusqu’ a ce que la liqueur soit alcaline; ce qui donne 
lieu A un dégagement d’acide carbonique et a un précipité géla- 
tineux de carbonate calcaire.’ In this statement he is followed 
by Sir Robert Kane and the majority of British compilers. Ber- 
zelius regarded it as a mixture of phosphate of lime and a little 
carbonate. He says in his ‘ Traité de Chimie,’seconde édition, 
Francaise, 1847, tome ui. p. 214:—‘ La liqueur acide, qui 
contient de l’acide phosphorique, du phosphate calcique et un 
peu de gypse, est décomposée par le carbonate sodique, de ma- 
niere qu il se précipite du phosphate calcique, mélé avec un peu 
de carbonate, tandis que le phosphate sodique, accompagné 
dune petite quantité de sulfate, reste en dissolution dans la 
liqueur.’ Gmelin considers it to be phosphate’ of lime and 
magnesia. In the translation of his ‘ Hand-Book,’ published 
by the Cavendish Society, 1849, vol. i. p. 91, it is said, 
speaking of the ordinary phosphate of soda :—‘ It may be pre- 
pared by adding carbonate of soda to the aqueous phosphoric 
acid obtained from bone ash, the liquid being kept at a boiling 
