130 On Apatite, Wagnerite, and some Metallic Phosphates. 



phorus over lime; M. Mauross* and M. Brieglebf, in conti- 

 nuation of the remarkable researches made in the laboratory of 

 Professor Wohler, have reproduced apatite in more distinct and 

 more beautiful forms by taking advantage of the double decom- 

 position of alkaline phosphates and chloride of calcium; M.Forch- 

 hammer J, by acting on'phosphate of lime with chloride of sodium, 

 has obtained very beautiful specimens of the same mineral 

 species. 



We employed a more direct and more general method, founded 

 on the fact that the phosphates are soluble at a red heat in the 

 chlorides of the metals whose oxides serve as base in the salts 

 employed, or in analogous chlorides. Thus by taking bone- 

 phosphate, and mixing it with sal-ammoniac to transform the 

 carbonate of lime, which it always contains, into chloride of cal- 

 cium, and adding an excess of chloride and fluoride of calcium, 

 we obtain by fusion at a red heat a fluid which appears homo- 

 geneous, and from which apatite crystallizes § on cooling. It is 

 well to operate as much as possible with crucibles or vessels of 

 graphite from gas-retorts; for the phosphates strongly attack clay 

 crucibles : the phosphate of lime may be replaced by any of the 

 phosphates mentioned. This may be prepared for the pui'pose 

 by calcining one equivalent of commercial phosphate of ammonia 

 with three equivalents of the oxide or nitrate of the metal in 

 question. The salt obtained is mixed with the coresponding 

 chloride and heated. On cooling, the excess of chloride is sepa- 

 rated by washing with distilled water. Iron apatite (Zwieselite) 

 is obtained by treating phosphate of iron with chloride of man- 

 ganese, a process which yields it in crystals frequently a centi- 

 metre long. 



The exact determination of the crystalline form of Wagnerite 

 is difficult on account of the numerous striae in the facets, more 

 especially of those zones the most easily measured We must 

 further observe that the phosphates retain fluorine with such 

 persistence as to lead to most serious errors if the analysis be 

 not made very carefully. 



The occurrence of apatite in veins has led M. Daubree to 

 think that this substance may have been conveyed into its posi- 

 tion in the form of volatile products, and in particular by the 

 action of chloride of phosphorus on lime, — a I'caction which in 

 fact produces apatite, for it brings together chloride of calcium 

 and phosphate of lime. The presence of fluorine would be more 

 difficult to explain on this supposition ; but an observation we 

 have made renders the hypothesis of M. Daubree admissible 



* Experiments, &c., Inaugural Thesis. Gottingen, 1852. 



t Liebig's Annalen, vol. xcviii. p. 95. % Ibid. vol. xc. p. "jT. 



§ This beautiful substance resembles the apatite of the Vesuvian lavas. 



