ADULTERATION OF POTASSA BY SODA. 
211 
known proportions of the concentrated solution of bicarbo- 
nate of soda, if there were not other obstacles. If, now, 
we seek for the reason why too little bicarbonate of soda 
was obtained we find it in the extreme difficulty of con- 
verting into bicarbonates, by a current of carbonic acid, a 
mixture of soda and potassa dissolved in a solution of bicar- 
bonate of soda ; for, at the end of three days' passing of 
carbonic acid into a solution of potassa, mixed with only a 
very small quantity of soda, the liquor had always an alka. 
line reaction, proving that all the alkaline carbonate had not 
been converted into bicarbonate : this circumstance renders 
this process, also, insufficient for the same sure and prompt 
determination of the quantity of soda contained in the po- 
tassa, although it may always be used for an approximative 
determination, as the foregoing investigations manifestly 
show. 
Moreover, as potassa (simple carbonate) cannot take 
water of crystallization, whilst anhydrous soda (this is the 
state in which it is found in the potassa which it serves to 
adulterate,) on the contrary, absorbs a very considerable 
quantity of it, in order to form crystals, it was natural to 
hope to determine, approximatively at least, the quantity 
of soda which might be found in the potassa, by estimating 
the proportion of water necessary for reducing a given 
quantity of potassa to a state of pappy mass ; so that, even 
after a long time, it will not solidify any more ; for it might 
be foreseen that there should be so much the more soda in 
the potassa, as more water is required to reduce the potassa 
to this state. 
In order to carry out this idea practically, I prepared the 
following mixtures of pure simple carbonate of potassa, and 
anhydrous simple carbonate of soda : — 
1. 90 gr. potassa and 10 gr. anhydrous soda. 
2. 80 " 20 " 
3. 70 « 30 " 
4. 60 " 40 " 
