536 Intelligence and Miscellaneous Articles. 



when prepared from a cold saturated solution by spontaneous evapo- 

 ration, their form being an acute octahedron with a square base. 



Osmiamate of potash is much less soluble in alcohol than in water ; 

 it dissolves without alteration, and decomposes but very little when 

 the solution is evaporated ; it contains no water of crystallization ; 

 it may be heated to 356" F, without decomposing, but it becomes 

 brownish and is rapidly decomposed at a higher temperature, with 

 violent projections. 



This salt yielded by analysis — 



Osmium 67*900 



Nitrogen 4-126 4*820 



Potash 16*126 



M. Gerhardt gives as an amended formula 0S03N(K). 



Osmiamate of Soda is best obtained from the silver salt and chlo- 

 ride of sodium ; the crystals are prismatic, contain water of ci*ystal- 

 lization, and are very soluble in water. 



Osmiamate of Ammonia is prepared in the same manner. It forms 

 large anhydrous crystals, which appear to be isomorphous with the 

 salt of potash ; at 258° F. it decomposes with explosion. This salt 

 is very soluble in water and in alcohol. 



Osmiamate ofBarytes readily crystallizes in yellow brilliant needles 

 of several lines in length. 1'his salt is readily soluble in water, and 

 explodes at about 300° F. It yielded by analysis — 



Barytes 23*88 



Osmium „ 61*07 



Nitrogen 4*269 



the formula according to M. Gerhardt being 0S03N(Ba). 



Osmiamate of Ammonia and Zinc is obtained either by dissolving 

 osmic acid in a solution of a salt of zinc in caustic ammonia, or by 

 mixing a solution of osmic acid in ammonia with the solution of a 

 salt of zinc. A yellow, bright crystalline powder is soon deposited, 

 which is deprived of the mother-water by washings with ammonia. 



This compound is very permanent ; it may be dried in the air, and 

 remains without losing ammonia. It is nearly insoluble in ammo- 

 nia, water decomposes it even when cold ; when boiled in water it 

 is completely decomposed with the deposition of oxide of zinc, the 

 disengagement of half of its ammonia, and yielding osmiamate of 

 ammonia. Formula according to M. Gerhardt 0S03N(Zn), 2NH3. 



Osmiamate of Lead. — A solution of nitrate of lead is not precipi- 

 tated by a concentrated solution of osmiamate of potash ; after some 

 time some crystals are however formed, which are not sufficiently 

 stable for examination. A solution of acetate of lead gives with the 

 solution of the osmiamates a non-crystalline precipitate, which is at 

 first of a dirty yellow colour, but it soon becomes of a purple tint 

 with the extrication of osmic acid. 



If a solution of chloride of lead, or a solution of nitrate of lead with 

 the addition of hydrochloric acid, be added to a solution of osmia- 

 mate of potash, a yellow crystalline precipitate is soon obtained, which 

 the authors consider to be a compound of equal equivalents of chloride 

 eind osmiamate of lead. 



