268 SALTS 



speedily plugged up the tubes, and prevented 

 the process from succeeding. I then suspended 

 a concentrated solution of carbonate of soda in 

 a distiller's fermenting tun, till the bicarbonate 

 was deposited in crystals. This process is easy, 

 because the bicarbonate of soda is much less 

 soluble in water than the carbonate. The colour 

 of this salt is white, and the crystals are semi- 

 transparent, and not altered by exposure to the 

 air. They have the shape of four-sided rectan- 

 gular prisms, terminated by an oblique rectangu- 

 lar base ; but were not susceptible of accurate 

 measurement. The taste is alkaline, but ex- 

 ceedingly weak, even when compared with the 

 taste of carbonate of soda. This salt gives a 

 purple colour to cudbear paper, in the same 

 manner as common carbonate of soda. At the 

 temperature of 64, 1 00 parts of water dissolve 

 9*33 parts of this salt. The solution cannot 

 be heated, far less concentrated, without driv- 

 ing off a portion of the acid, and converting 

 the salt first into sesquicarbonate, and finally in- 

 to common carbonate of soda. 



When 10-625 grains of this salt in crystals are 

 fused in a platinum crucible, they lose 3-875 

 grains of their weight, and leave a residue of an- 

 hydrous carbonate of soda, weighing 6*75 grains. 

 106-25 grains of the crystals dissolved in dilute 

 sulphuric acid with a very violent effervescence ; 

 and the Joss of weight, owing to the escape of 



