21Q Miscellaneous Intelligence, 



Considered as a dipermuriate of mercury, the composition of 

 tiiis substance is as follows : 



Muriatic acid . . 1 atom . 37 or 7.8 

 Peroxide of mercury, 2 atoms . 432 . 92.2 



469 100. 

 Phil Mag. N. .v., vii. 129. 



15. Reduction of Nitrate of Silver. — M. Charles de Filiere pre- 

 pared a large quantity of nitrate of silver in 1826. The finest 

 crystals were put into unsized paper, and then put hastily into a 

 card-board box, in such a manner, however, as to prevent any 

 contact of them with the bodies held in suspension in the atmos- 

 phere. 



This packet having been refound in the month of November, 

 1829, was examined. The paper had acquired the usual deep 

 violet tint; but when opened, the crystals were unchanged in form, 

 |?ut perfectly reduced, and now consisted of very malleable me- 

 tallic silver. — Ann. de Chimie, xlii. 335. 



16. 0?^ some Properties of Silver. — M. Weslar states, that chloride 

 of silver, blackened by light, is not a mixture of reduced silver 

 and undecomposed chloride, but a sub-chloride of silver unat- 

 tackable by nitric acid, though resolved by ammonia and a solu- 

 tion of common salt into metallic silver and chloride. It cannot 

 be obtained pure by exposure of the chloride to light, but may 

 by allowing silver to remain in a solution of muriate of copper or 

 iron. When silver containing copper is blackened by solution of 

 muriate of ammonia, it is in consequence of the formation of this 

 chloride. 



Silver left for a long time in strong solution of common salt is 

 attacked j the liquid becomes weakly alkaline, and on evaporation 

 yields crystals consisting of the combined chlorides of sodium 

 and silver. 



It is known that a hot solution of sulphate of iron dissolves sil- 

 ver, and that silver falls as the solution cools: but the metal is 

 not totally precipitated, a part remains dissolved at common tem- 

 peratures, and this is in greater proportion as the solution is 

 more acid. Dilute sulphuric acid does not act on silver at com- 

 mon temperatures, but it is only necessary to add a drop of solu- 

 tion of sulphate of iron to make it do so. It appears that the 

 oxygen of the air is conveyed to the silver by means of the solu- 

 tion of iron, the iron, after giving oxygen to the silver^ retaking 

 more from the air. 



Solution of chloride of silver in common salt is not decom- 

 posed by potash, probably in consequence of the great affinity of 

 the chlorine for silver, and the potassium for oxygen. It is owing 

 to the same affinities that the complete decomposition of the chlo- 

 ride of sodium by oxide of silver can be effected, — Phil, Mag, 

 N, S, vii. 58. 



