2^1 
of a newly discovered vegetable acid. 
would crystallize ; it must therefore be used hot. The stream 
of sulphuretted hydrogen passing through so high a column 
of fluid soon separates the lead, while the pure vegetable 
acid is liberated, contaminated indeed with a little sulphu- 
retted hydrogen. This gas does not disappear completely 
by boiling, for the acid retains the odour, be it ever so long 
boiled; exposure for a few days in an open vessel dissipates 
it completely. 
In preparing this acid, it is not necessary, as it is in the 
process for malic acid, to saturate the juice of the berries with 
potash, at the commencement of the process : for of the two 
compounds formed after the mixture with acetate of lead, the 
malate dissolves in the evolved acetic acid in preference to 
the other. The colouring matter, which adheres obstinately 
to the malate of lead, is very apt, when extricated during 
the washing with boiling water, to tinge the otherwise per- 
fectly colourless crystals, which form as the liquor cools. 
This is a great inconvenience, for the colouring matter cannot 
be washed away, even by cold water, without decomposing a 
quantity of the salt : hence the only remedy is, to reject all 
the crystals formed in the coloured washings, and to reserve 
those only that are of a pure whiteness. The crystals are 
of so delicate a fabric that they must be separated by the 
filter. When dried on paper, by exposure to air, they form 
a white brilliant flake of a silver lustre, resembling well- 
prepared acetate of mercury, but still more beautiful. 
As to the amorphous crystalline grains which first attracted 
my attention, the following experiment elucidates the theory 
of their formation. A quantity of the pure acid obtained by 
the above process, was boiled for some time on an excess of 
MDCCCXV. I i 
