.>!() SALTS 



very readily in water, and reddens vegetable 

 blues. 



9. Oxalate of alumina. Oxalic acid dissolves 

 hydrate of alumina with facility. The saturated 

 solution is transparent and colourless ; it has a 

 sweet and astringent taste, and reddens vegeta- 

 ble blues. When evaporated, the oxalate of 

 alumina remains behind in the state of a semi- 

 transparent amber-coloured crust, very similar 

 in appearance to gum, or albumen which has 

 been dried in a low heat. It dissolves with fa- 

 cility in water, but may be exposed to the air 

 without absorbing moisture. 



10-125 grains of this salt, when kept in a red 

 heat for some time, leave 2-25 grains of alumina. 

 10-125 grains of the same salt were dissolved in 

 water, and mixed with a sufficient quantity of 

 muriate of lime. No precipitate fell ; but a 

 slight white powder appeared when the liquid 

 was heated. It was evaporated to dryness in a 

 gentle heat, digested in water, and thrown on 

 the filter. The weight of the oxalate of lime re- 

 tained on the filter was 10 grains. This is very 

 nearly equivalent to 4-5 grains of oxalic acid. 

 From these experiments it is obvious that the 

 constituents of the salt are 



1 atom oxalic acid 4'5 



1 atom alumina 2-25 



3 atoms water 3-375 



10-125 



