ADULTERATION OP POTASSA BY SODA. 
215 
The circumstance should furnish one of the hases for the 
process to be followed; for the other, it wa nsecessary to 
find the space which would be occupied by the quantity of 
bitartrate of potassa which might be formed by 100 grains 
of perfectly pure simple carbonate of potassa. 
In order to solve this question, after some preliminary 
investigations, of which it is useless to speak, I took a glass 
tube, of as equal a diameter as possible, and of equal thick- 
ness throughout — about three feet in length, and five lines 
in diameter — and I closed it at one of its extremities 
I then put into this tube a solution of bi;artrate of potassa 
which had been prepared in the following manner: — I 
poured into a small glass matrass, capable of being corked, 
on one-fourth of the quantity of bitartrate of potassa, which 
100 grains of pure carbonate of potassa can furnish, that is 
to say on 68.2 grains about two ounces and a quarter of 
solution of bitartrate of potassa saturated at the ordinary 
temperature ; I well corked it, and heated it cautiously, in 
order to eifect the complete solution of the bitartrate of 
potassa. 
The warm and perfectly clear solution was then promptly 
poured into the above-mentioned tube ; the matrass was 
washed with a smaller quantity of solution of bitartrate of 
potassa, saturated cold : I well corked and agitated, until 
the temperature of the tube and its contents was completely 
reduced to that of the surrounding atmosphere, or rather to 
that of the solution of bitartrate of potassa, at the com- 
mencement of the experiment. I plunged the tubes seve- 
ral times into cold water, in order to accelerate cooling 
The crystalline powder thus separated, whose quantity, 
as may readily be conceived, should correspond to 25 grains 
of potassa, was collected in the smallest possible space by 
striking the tube several times on a hard body, and when 
new blows did not heap it up, I made a mark with a file 
on the tube at the level obtained by the crystalline powder 
of bitartrate of potassa. The space below the mark was 
