I 



and some artificial species of Metallic Phosphates. 129 



Apatites, 



Composition. Mineralogical names. 



Lime apatite . . . 3(P0^ 3CaO)(Cl Ca). Apatite. 

 Lead apatite . . . 3(P0^ 3PbO)(Cl Pb). Pyromoi-phite. 

 Baryta apatite. . . 3(P0\ 3BaO)(ClBa). Artificial species. 

 Strontiau apatite . . SfPO^, 3SrO) (CI Sr). Artificial species. 



TVagneriies. 



Magnesia Wagnerite . (P0^ 3 MgO) (CI Mg) . Wagnerite. 

 Lime Wagnerite . . (PO^ 3CaO) (ClCa). Artificial species. 

 Manganese Wagnerite (PO^ 3 MnO) (CI Mn) . Artificial species. 

 Wagnerite of iron and rpp.5 o/Mn \"l Tp, /Mn"\^ Zwiesel- 

 manganese . . V ^ ' ^(.Fe Oj^ ^^^Fe Jj" ite. 



Li these bodies we have been able to replace a part or even 

 the whole of the chlorine by fluorine, without in general changing 

 the crystalline form, showing in this case the isomorphism of 

 fluorine and chlorine, which hitherto has only been strictly de- 

 monstrated in a few cases. 



It will be observed that the bases in apatite are such metallic 

 oxides as, in combining with carbonic acid, give rhombic carbon- 

 ates of the same form as Arragonite ; theWagnerites, on the other 

 hand, are exclusively composed of such metallic oxides as give, 

 when combined with carbonic acid, rhombohedral carbonates, or 

 spars of the same form as calcareous spar. To complete this 

 singular comparison, it will be remarked that carbonate of lime 

 is dimorphous, crystallizing either in rhombic prisms (Arragonite) 

 or in rhombohedra (calcareous spar). Hence the lime officiates 

 as intermediate agent, oc pivot as it has been elsewhere* called, 

 between these two groups of metallic oxides. It is the same 

 here. We have obtained a calcareous Wagnerite, hitherto un- 

 known, by replacing, either wholly or partially, magnesia by lime, 

 and fluorine by chlorine. This calcareous Wagnerite has there- 

 fore the composition 



P0^3CaO(ClCa), 



which has been confirmed by analysis, and which approximates 

 it to the second group of chlorophosphates. 



Moreover, all our eff"orts to obtain Wagnerite from purely 

 Arragonitic oxides, and a})atites from purely spathic oxides, have 

 been unfruitful, so that the two divisions of the metallic carbon- 

 ates appear again in the phosphates ; but here we not only find 

 incompatible crystalline form, but also diff'crent composition. 



M. Daubreef has prepared apatite by passing chloride of phos- 



* Comptes Rendus, vol. xxxviii. p. '101. 



t Annules des Mines, 4 stT. vol. xix. p. 654. 



Phil. Mag. S. 4. Vol. 17. No. 112. Feb. 1859. K 



