of a newly discovered vegetable acid. 233 
opinion now suggested itself, which the following trials 
greatly strengthened. 
In order to obtain the acid of the saturnine precipitate, 
the latter was boiled with dilute sulphuric acid : the liquor 
became red and transparent, while the sulphate of lead sub- 
sided to the bottom. Imagining that I had now obtained the 
acid in a state' of sufficient purity, although coloured with 
adhering vegetable matter, I thought to separate the sediment 
by filtration, but was disappointed : for the liquor came through 
very turbid, notwithstanding that the supernatant liquor had 
been transparent. It was apparent, therefore, that the sul- 
phuric acid being in too small a quantity, had displaced but 
a part of the vegetable acid, that the latter dissolved the 
remaining part of its own combination with lead, and depo- 
sited it when the solution touched any thing cold, thus pro- 
ducing the turbidness. After some hours, the turbidness in 
the filtered liquor subsided, forming a stratum on the bottom 
of the vessel, over which lay a number of crystals. 
The theory of the crystalline formation in the washings of 
the precipitate now became obvious. It appeared that when 
the saturnine compound was washed with cold water, no 
other effect than edulcoration was produced : but that hot 
water partially decomposed the mass into a super and a 
sub-salt, the former of which being soluble in boiling water, 
filtered through, but on cooling, deposited crystals of the 
neutral salt, while free acid was left dissolved in the liquor. 
The first washing contained most free acid, and therefore 
suffered least of the neutral salt to crystallize. 
The red acid liquor, as has been stated, contained much 
lead, and this it was necessary to separate. The most unex- 
mdcccxv. H h 
