GEATES. 79 



2d. Lime water, added to a solution of an alkaline geate, 

 forms a precipitate of geate of lime. It is to be observed, 

 that a cautious and gradual addition of lime water forms a 

 precipitate, which immediately re-dissolves. This is soluble 

 geate of lime. It requires 2000 parts of water to dissolve 

 it, being a very little more soluble than geine itself and only- 

 half as soluble as lime alone. * An excess of lime water pre- 

 cipitates all the geine as insoluble geate of lime. The prop- 

 erties of this insoluble geate of lime, are, 



119. 1st. Almost perfect insolubility in water and alka- 

 lies. 



2d. Decomposable by alkalies. 



120. Geate of magnesia is easily soluble in water. It is 

 the most soluble of all the earthy geates. It requires only 

 160 parts of water to dissolve one of geate of magnesia. 

 It is decomposable by alkalies, and then both acid and base 

 are dissolved. The geates of lime and magnesia, when 

 exposed to air, absorb carbonic acid ; a salt is formed, con- 

 taining an excess of geine, that is, the carbonic acid unites 

 with a part of the lime. These super-geates, as they are 

 termed, are always much more soluble than the neutral 



121. Geate of alumina is soluble in water, and in alkali, 

 without decomposition. It requires 4200 parts of water to 

 dissolve it, but is abundantly soluble in alkali. 



122. Geate of iron requires 2300 parts of water to dis- 

 solve it. Like geate of alumina, it dissolves easily in alka- 

 line carbonates. 



123. Geate of manganese requires 1450 parts of water to 

 dissolve it, and though soluble in ammonia, is insoluble in 

 potash or soda. 



124. The properties of the geates are of the highest prac- 

 tical importance. The tRree earths, lime, magnesia, and 



