M. Briegleb on the action of Phosphate of Soda on Fluor-spar. 455 



and sodium, converted both ultramarines when gently heated into 

 red ultramarine. Green ultramarines, when not acted upon by 

 strong agents, had always a tendency to pass into blue. 



The same subject has been ably investigated by Breunlin, an 

 abridgment of whose paper will appear in next month's Magazine. 



With a view of obtaining an easy method for the preparation 

 of fluoride of sodium, which might serve as a useful material for 

 the preparation of fluorine compounds in general, Briegleb in- 

 vestigated the action of phosphate of soda on fluor-spar. The 

 two substances, mixed together in the proper proportions, were 

 fused in a Hessian crucible, and the fused mass poured on an 

 iron plate. The last parts poured out of the crucible were com- 

 posed of a mass of small crystals. These were insoluble in water, 

 and on examination were found to be apatite. This formation 

 of apatite has been already observed by Manross. The fused 

 mass was boiled with water for some time; some fluoride of 

 sodium was obtained, but it bore no adequate proportion to the 

 quantity that the theory required. An attempt to produce fluo- 

 ride of potassium in this way gave still less favourable results. 



^^Tien, instead of extracting the fused mass with boiling water, 

 it was digested with water on the water-bath for some days, and 

 the hquid thus obtained filtered and evaporated, beautiful trans- 

 parent octahedrons were obtained. These proved to be a double 

 salt of phosphate of soda and fluoride of sodium, — 



3NaO, P05-t-NaF + 24H0. 

 This salt may also be obtained by digesting for several days at a 

 moderate heat, finely powdered cryolite with a solution of phos- 

 phate of soda and caustic soda. 



An attempt to produce potash and ammonia salts correspond- 

 ing to the above gave negative results. 



A double salt of arseniate of soda and fluoride of sodium is 

 obtained by fusing arseniate of soda and fluor-spar. To this, 

 arseniate of soda is necessary; and it is better to combine its 

 preparation with this reaction, by fusing together a mixture of 

 nitrate of soda, arsenious acid, carbonate of soda, and fluor-spar. 

 After maintaining the fusion some time, the mass is poured out 

 and digested with water ; the salt then dissolves up and may be 

 easily crystallized. The crystalline form of this salt is exactly 

 the same as that of the phosphoric acid compound. 



These salts may be considered to belong to the group of 

 alums : — 



AP 0^ 3S03 + KO SO^ -K 24H0. Common alum. 

 Na^ 03 PO^-f Na Fl + 24HO. New salt. 

 Na" 0^ AsO^ + Na Fl + 24HO. New salt. 



