144 
ON SESQUICARBONATE OP SODA. 
If they are examined at the expiration of a few weeks, it is 
found that they have assumed, by absorption of water, a 
perfectly crystalline appearance. 
The quantitative analysis of this salt has demonstrated 
that the present formula (So O 2 . 3C 2 +4H 0,) is not 
quite correct, but that its composition corresponds to the 
formula So O 2 . 3C 2 4-3H 0. 
100 parts gave: — - 
Soda 40.00 
Carbonic acid 43.06 
Water 16.94 
100.00 
Which gives- 
caicuiated in 100 parts 
2 at. soda • = 781.8 40.12 
3 " carbonic acid = 829.2 42.56 
3 « water = 337.4 17,32 
1 " crystallised sesquicarbonate 'of soda = 1948.4 100.00 
Heated to redness over a spirit lamp, sesquicarbonate of 
soda leaves, the same as the bicarbonates of potassa arid 
soda, a portion of carbonate. It partakes, then, with these 
bicarbonates, the peculiarity of allowing the excess of car- 
bonic acid to be more completely disengaged by the ebul- 
lition of its solutions, than by the calcination of the dry 
salt. Ibid- 
