On the Berries of the Rhus Coriaria. 
149 
To purify the crystals, they are to be pulverized, mixed 
with animal charcoal, and dissolved in boiling water, this 
method, however, occasions some loss. In fact, the charcoal 
is not necessary, all that is requisite being to redissolve the 
impure salt and to again crystallize it. 
Pure malic acid may be made from this salt by dissolving 
it in water, precipitating the lime by carbonate of potassa, 
and decomposing the solution by acetate of lead. The pre- 
cipitate obtained is malate of lead, which when dried is very 
brilliant and of a dazzling whiteness. If the precipitation is 
performed on a hot solution, the precipitate assumes on cool- 
ing the form of small brilliant scales; these are to be collected 
on a filter, and after being drained and washed with cold 
water, they are to be suspended in water and decomposed 
by a current of sulphuretted hydrogen, the sulphuret sepa- 
rated, and the acid liquid evaporated, when it will afford pure 
malic acid in needles, forming mammillary groups by their 
agglomeration; these crystals deliquesce on exposure to the 
air. 
Mr. Tromsdorff next examined the syrupy mother water 
spoken of above ; he diluted it with water and added a hot 
solution of gelatine; a considerable quantity of a combina- 
tion of gelatine and tannin separated from the fluid, in the 
form of an elastic mass; but one portion of the precipitate re- 
maining in suspension in the fluid, this continued turbid even 
after filtration. It was then agitated with a little white of 
egg and rapidly boiled, when it became clear and was strained 
through a woollen cloth. It had now lost all its astringent 
taste, had no action on the salts of iron, or on a solution 
of isinglass; but still retained some colour, and had a strong 
acid. By a slow evaporation and the addition of alcohol, it 
afforded a large quantity of acid malate of lime in dark 
crystals, which were purified by redissolving and again crys? 
,tallizing. Journ r de Pharm* 
