186 Mr GRAHAM'S Account of the Formation of Alcoates. 



the acid, and decomposing the salt. For this salt may be wholly 

 reduced in a glass-tube by the heat of a spirit-lamp, and yet a 

 sand-bath heat of 600 or 700 is not sufficient to drive off all 

 its water of crystallization. But a partial decomposition of this 

 salt is of no great consequence, as alcohol dissolves the unde- 

 composed portion of the salt, while the magnesia resulting from 

 the decomposition precipitates, and may be separated by decant- 

 ing the solution, or by filtering. 



Four parts alcohol at 60 dissolve one part nitrate of magne- 

 sia, and boiling alcohol dissolves more than half its weight of 

 this salt. From the great difference between the solubility of 

 this salt at high and low temperatures, the alcoate is obtained 

 with facility. A hot solution, containing a greater proportion of 

 nitrate than one part to three parts alcohol, became, upon cool- 

 ing, an irregular dry mass, which could be indented by the point 

 of a glass-rod, but was much harder than the alcoate of chloride 

 of calcium. In solutions considerably weaker crystals were de- 

 posited on cooling, which sometimes resembled the crystals of 

 the former alcoate, but were much smaller, and less distinct ; 

 but more frequently, the crystals were exceedingly minute, and 

 detached, without any regular form which could be discerned. 

 But the great mass of crystalline matter precipitated in scales of 

 a pearly lustre and whiteness, but apparently made up of the 

 small crystals. 



Dried by pressure, in blotting paper, this alcoate much resem- 

 bled the alcoate of chloride of calcium in external characters. It 

 sank in water, but floated on the surface of a saline solution of 

 the specific gravity 1.1. Heated, it melted readily ; boiled, and 

 much alcohol was given off. When boiled violently, red fumes 

 rise with the alcohol-vapour ; but when dried slowly, no loss of 

 acid takes place. 



Upon cautiously heating 13.4 grains alcoate of nitrate of mag- 

 nesia to dryness, there remained 3,56 grains nitrate of magnesia. 



