M. Debray on some Crystallized Phosphates and Arseniates. 233 



and often sooner, the following new salts in well-defined crys- 

 tals : — 



Phosphate of ammonia and nickel . 2NiO, NH 4 0,P0 5 + 12HO 

 Phosphate of ammonia and zinc . . 2ZnO,NH 4 0,P0 5 + 12HO 

 Phosphateofammoniaandmanganese 2MnO,NH 4 0,P0 5 + 2HO 

 Phosphate of ammonia and iron . . 2FeO,NH 4 0,P0 5 + 2HO 



At a temperature of about 80° C. ammoniacal double salts are 

 obtained with magnesia, cobalt, nickel, manganese, and iron in 

 nacreous crystals, which have the general formula 



2RO,NH 4 0, P0 5 + 2HO. 

 Zinc forms an exception ; it produces an anhydrous phosphate. 

 Chancel's phosphate of ammonia and cobalt, 

 2CoO,NH 4 0,P0 5 + 12HO, 



when left in contact with a concentrated acid solution of phos- 

 phate of ammonia for seven or eight days, is transformed into 

 tolerably large rose-coloured crystals of a phosphate which is also 

 insoluble, and which has the composition 



CoO,NH 4 0, HO,P0 5 + 4HO. 



Phosphate of iron undergoes a similar change. 



In very acid liquids no precipitates are formed, but beautiful 

 crystals are obtained on spontaneous evaporation. 



With phosphate of ammonia and magnesian salts in excess 

 no ammoniacal phosphates are obtained, and the products vary 

 with the temperature. Thus the salts of magnesia and of manga- 

 nese give phosphates in the form of fine rhomboidal octahedra, of 

 the following composition : 



2MnO, HO, P0 5 + 6HO and2MgO, HO, P0 5 + 6HO. 



At 100° C. manganese gives a tribasic phosphate, 

 ~ 3MnO,P0 5 + 3HO, 



which has the form of Hureaulite, and may be considered as a 

 variety of this mineral free from iron. 



Arseniate of ammonia gave precipitates which could not be 

 transformed at the ordinary temperature ; but kept for several 

 days at 100°, well-defined crystals were obtained. Those of zinc 

 and of manganese are as follows : — 



2MnO, HO, As0 5 + 2HO ; 2ZnO, HO, As0 5 + 2HO. 



With phosphate of soda in excess and salts of the magnesian 

 group the products vary with the nature of the salt employed. 

 The following are the principal ones obtained : — 



Phosphate of magnesia . . 2MgO, HO, P0 5 + 14 HO 

 Phosphate of zinc .... 3ZnO,P0 5 + 4HO 

 Phosphate of iron . . . . 3FeO,P0 5 + 8HO 

 Phil. Mag. S. 4. Vol. 28. No. 188. Sept. 1861. R 



