148 
Selected Articles. 
ART. XXXIII.— ON THE BERRIES OF THE RHUS CORIARIA. 
By J. JB. Tromsdorff. 
This species of Rhus is a shrub, found in poor ground r 
The leaves and young branches are ground and sold in com- 
merce under the name of Sumach; and are much used in the 
preparation of morocco leather. 
The berries are distinguished by an acid and slightly as- 
tringent taste. M. Tromsdorff analyzed them many years 
since and obtained an acid salt, which he erroneously sup- 
posed to be acid tartrate of potash ; his late experiments on 
a large quantity of these berries, however, have enabled him 
to correct his mistake. 
The acid of these berries he finds to be the malic, princi- 
pally combined with lime in the state of a super salt ; but 
they also contain a small quantity of maiate of potash. The 
acid exists in the greatest proportion in the down or coating 
of the berries. 
This fruit may be advantageously employed to obtain a 
pure malic acid, by the following process. Boiling water is 
to be poured on the berries deprived of their footstalks, and 
placed in an earthen pot ; after remaining in the fluid for about 
a quarter of an hour, the whole is to be poured on a linen 
strainer, a red and very acid liquid passes through ; the resi- 
due is to be well washed with boiling water, and the wash- 
ings added to the first solution. 
This liquid is to be evaporated in a porcelain capsule by a 
gentle heat; during this process a slight deposit of extractive 
matter takes place, when the fluid is to be again strained and 
the evaporation continued. When this has reached a certain 
point, a large quantity of crystals of a very acid salt of a 
whitish gray colour will be formed. The last crystallizations 
will be of a darker colour, and contain a certain proportion 
of maiate of potash. 
Finally, a thick and very acid liquid remains from which, 
no crystals can be obtained, which wilj be presently spoken of. 
