322 Intelligence and Miscellaiieous Articles. 



If excess of the alkaline carbonate be used in the preparation of 

 the compound, and the earthy phosphate is fused, the washed com- 

 pound which results is mixed with a greater or smaller proportion 

 of earthy carbonate. The compounds which were prepared and 

 analysed were the following : — 



1. Phosphate of potash and lime (KO + 2CaO + PO^). 



2. Phosphate of soda and lime (NaO + 2Ca04-P05). 



3. Phosphate of potash and strontia (KO + 2SrO + PO*). 



4. Phosphate of soda and strontia (NaO + 2Sr04-PO*). 



These salts are transformed, by washing, into a compound which 

 nearly approaches the combination — 



2(Na + Sr04-P05) + (HO + 2SrO + P05). 



5. Phosphate of potash and barytes (KO+2BaO + P05). 



6. Phosphate of soda and barytes (NaO + 2BaO + PO^). 



These two combinations, especially that of potash, do not seem 

 susceptible of being obtained pure. Among all the compounds of 

 phosphate of soda with the alkaline earths, the phosphate of barytes 

 is mostly, though not completely decomposed, by ti'eatment with the 

 alkaline carbonate ; but on treatment with water, part of the alkali 

 in the insoluble double salt is easily replaced by an equivalent of 

 water. 



7. Phosphate of potash and magnesia (KO + 2MgO+PO*). 



8. Phosphate of soda and magnesia (NaO + 2MgO + PO^). 

 These two compounds should be washed with ammonia water ; in 



spite of this precaution, however, a great part of the alkali, espe- 

 cially in the latter, is replaced by water. 



9. Phosphate of lithia and lime (LiO + 2Ca04-PO*). 



If earthy pyrophosphates be calcined with the metallic chlorides 

 of the alkalies, the chlorine is expelled from them by the interven- 

 tion of moist air, in the form of hydrochloric acid gas, and compounds 

 are formed analogous to those which have been described. 



But if the earthy phosphates are contained at the same time as 

 the alkalies in acid solutions, the first may be precipitated by am- 

 monia, without the precipitate containing any fixed alkali. The 

 compound described cannot therefore be formed in the humid way. 

 The whole of the earthy phosphate is not precipitated, on account of 

 the presence of the ammoniacal salt. 



In certain circumstances there appeared also to be formed analo- 

 gous combinations of phosphoric acid, which probably consist of two 

 atoms of alkali, one atom of earth, and one atom of phosphoric acid. 

 These compounds are soluble in water. 



When an organic substance is carbonized, and the coaly mass is 

 exhausted by water, the aqueous solution contains earthy phos- 

 phates (especially phosphate of lime), which separate on evaporation 

 to dryness, and the dry residue is dissolved in water. The earthy 

 phosphates are dissolved by the alkaline phosphates, and form double 

 salts with them. 



When pyrophosphate of soda is gently heated with an excess of 

 earthy carbonate, or when an organic substance is exposed to suffi- 

 cient heat to carbonize it, the aqueous solution of the calcined mass 



