210 
ADULTERATION OF POTASSA BY SODA. 
moist, and 16.9 grains of the same salt dry. A solution of 
70 grains of potassa and 30 grains of anhydrous carbonate 
of soda, gave 44.1 of humid bicarconate of soda, and 36.7 
of the same salt dry. 
A solution of 60 grains of potassa and 40 grains of anhy- 
drous carbonate of soda gave, by the same process, 59.1 of 
humid bicarbonate of soda, and 49.7 of the same salt dry. 
Finally a solution of 50 grains of potassa and 50 grains 
of anhydrous carbonate of soda, gave 72.2 of humid bicar- 
bonate of soda, and 58.6 of the same salt dry. 
If we examine this result a little nearer, we shall find 
that the quantities of bicarbonate of soda obtained are too 
small. 
For the following quantities Should give the following 
of simple carbonate of quantities of crystallized 
soda — bicarbonate : — 
10 17.5 
20 . 35 
30 52.5 
40 70.0 
50 87.5 
But they gave only — Deficiency : 
14.6 2.9 
24.9 10.1 
36.7 15.8 
49.7 20.3 
5S.5 29.0 
This too small produce is also increased by the impossi- 
bility of driving off all the liquid by means of the simple 
pressure of the bicarbonate of soda separated and collected 
on a filter, and it indeed suffered an increase of weight pro- 
portionate to the fixed principles contained in the quantity 
of the liquid which was not separated by pressure. More- 
over, this difference would be insignificant, and it would be 
easy to calculate it by the weight of the bicarbonate of soda 
obtained in the humid and dry states, according to the 
