4-06 Intelligence and Miscellaneous Articles, 



the phaenomena, so that very variable mixtures of common salt, sul- 

 phate of magnesia, and chloride of magnesium are obtained. 



The results of evaporation are still more variable above 35°. The 

 mixtures of the salts deposited undergo numerous differences in their 

 composition, without the possibility of foretelling the result of the 

 precipitations: some contain from O'o to 0"17 of their weight of 

 potash ; it sometimes happens that this substance is found in depo- 

 sits formed in solutions, the density of which is only from 34° to 

 35° ; these deposits are derived from variations in the composition of 

 the waters. — L'Institut, Fevrier 27, 1850. 



ON NEW COMPOUNDS OF AMMONIA WITH FERROCYANIDE AND 

 FERRIDCYANIUE OF NICKEL. BY M. A. REYNOSO. 



When excess of ammonia is added to recently precipitated and 

 moist ferrocyanide of nickel, it dissolves at first, changes its colour, 

 and soon produces a precipitate composed of a multitude of very fine 

 needles of a violet colour ; these are the ammoniacal ferrocyanide of 

 nickel. It may also be prepared by adding ferrocyanide of potassium 

 to a solution of nickel containing much ammonia, or by causing a 

 solution of the salt of nickel to act upon a mixture of ammonia and 

 ferrocyanide of potassium. In every case the crystals of the salt are 

 finer as they are more slowly formed ; that is to say, when there is 

 much ammonia, and the solution is consequently very dilute. The 

 analysis of this salt indicated its formula to be 2Ni Cy, Fe Cy, SNH^, 

 4H0. 



When ferrocyanide of potassium is poured into a solution of am- 

 moniacal nitrate of nickel, a greenish- white precipitate is obtained, 

 which after being well dried is a mass of a very deep green colour, 

 which becomes white by pulverization. It adheres to the tongue, 

 is insipid, and completely insoluble in water. Ammonia dissolves it 

 and converts it into quinto-ammoniacal ferrocyanide. Heat decom- 

 poses it, evolving ammonia and ferrocyanide of ammonia, leaving a 

 carburet which fuses in burning. 



This salt is the biammoniacal ferrocyanide of nickel ; its formula 

 is 2Ni Cy, Fe Cy, 2NH^ HO. 



The ferridcyanide of potassium, poured into ammoniacal nitrate 

 of nickel, produces a fine yellow precipitate, soluble in excess of am- 

 monia. It is the biammoniacal ferridcyanide of nickel, the formula 

 of which is SNiCy, Fe^ Cy3, 2NH3, HO. 



All the ferrocyanides and ferridcyanides of the metals whose oxides 

 are soluble in ammonia are themselves soluble in ammonia. The 

 alkaline solution of ferridcyanide of cobalt is of a very deep red 

 colour. The ferrocyanides and ferridcyanides of the metals whose 

 oxides are soluble in potash, are themselves soluble in potash. Thus 

 potash added to ferrocyanide of zinc produces immediately ferrocy- 

 anide of potassium and oxide of zinc, which dissolves in the excess 

 of potash. If the potash be added with precaution, on filtering, 

 the liquor contains merely ferrocyanide of potassium, and oxide of 

 zinc remains on the filter. With ferrocyanide of mercury the reac- 



