172 



REPORT 1861. 



siderably increased by the presence of sal ammoniac in the water with which 

 the phosphatic materials have been brought into contact. 



In the case of precipitated phosphate of" lime, the difference in the solu- 

 bility in distilled water and water containing sal ammoniac is very great 

 indeed. In mineral analyses in which phosphate of lime has to be determined, 

 the filtrate from the phosphates contains usually sal ammoniac, and in this 

 solution phosphate of lime, it has been shown, is soluble to a considerable 

 extent ; it is therefore desirable to remove from this solution the lime by oxa- 

 late of ammonia, then to evaporate to dryness, and to drive off the ammonia- 

 cal salts by heat. In the residue the small but appreciable quantity which ought 

 by no means to be neglected in accurate analysis will be found, and may 

 be determined by 2NaO, POg and ammonia. 



Solubility of phosphate of lime in solutions containing 1 per cent, of carbonate 



of ammonia. 



Carbonateof ammonia, like sal ammoniac, appears likewise to render phos- 

 phate of lime more readily soluble than it is in pure water. This will be seen 

 by the following results : — 



Amount of phosphate Calculated 

 dissolved in 1 pint. per gallon. 



Exp. grs. grs. 



'1st 1-42 11-36 



2nd 1-40 11-20 



1st -21 1-68 



2nd -22 1-76 



1st -19 1-52 



2nd -21 1-68 



Precipitated phosphate of lime 



Suffolk coprolites 



Cambridgeshire coprolites 



Solubility of phosphate of lime in water containing 1 per cent, of common salt. 



I have now to mention experiments which have shown me that neither 

 chloride of sodium nor nitrate of soda has increased in any marked manner 

 the solubility of phosphate of lime in the materials used in my experiments. 



The results obtained with solutions containing 1 per cent, of chloride of 

 sodium are embodied in the following table : — 



Amount of phosphates dissolved by water containing 1 per cent, of chloride 



of sodium in solution. 



Calculated 

 In 1 pint. per gallon. 



Exp. grs. grs, 



rist -52 4-16 



\ 2nd '55 4-40 



3rd -58 4-64 



4th -57 4-56 



Precipitated phosphate of lime 



Pure bone-ash yielded 1-20 grs. of bone- 

 earth to water per gallon 



Commercial bone-ash yielded 1-76 grs. of 

 bone-earth to water per gallon 



Cambridgeshire coprolites 



Suffolk coprolites 



1st 

 2nd 

 fist 

 2nd 

 1st 

 2nd 



•16 

 •18 

 •10 

 •12 

 •10 

 •12 



It might appear that in the first four experiments the presence 

 salt had reduced the solubility of precipitated phosphate of lime 



•96 



V28 

 1-44 

 •80 

 •96 

 •80 

 •96 



of common 

 but I do 



