LACTUCA VIROSA AND SATlVA. 
37 
in water and neutralized with caustic ammonia, was employed 
for the following reactions : — Acetate of barytes and solution 
of lime, as well as solution of gypsum, produced no change ; 
acetate of lead, a precipitate which was soluble in the free acid, 
in dilute nitric acid, and in an excess of the precipitant ; ni- 
trate of silver, a pulverulent precipitate soluble in caustic am- 
monia and nitric acid ; solution of corrosive sublimate, no 
change ; but with solution of the protonitrate of mercury, an 
abundant caseous precipitate; perchloride of iron, a dark 
brown voluminous precipitate ; and acetate of zinc, a white 
precipitate, which was soluble in much hot water. 
From these preliminary tests, there can be scarcely any 
doubt that the peculiar acid of the plant is succinic acid. 
Lactuca saliva was treated in the same manner as Lac- 
tuca virosa, and curiously enough yielded the same results, 
except as to the amount of succinic and malic acids. 100 lbs. 
of the fresh Lactuca sativa, gave 122 grs. of succinic acid 
and 1 1 drms. of dried malic acid ; 50 lbs. of fresh Lactuca 
virosa yielded 28 grs. pure crystallized succinic acid and 3 
drms. of dried malic acid. 
An Extr actum Lactucx virosse afforded, when treated 
in a similar manner, on an average 1 gr. of succinic acid 
per ounce. In this examination the tests for oxalic acid 
were likewise repeated, but with a negative result. 
According to the most recent analysis, an oxalate is con- 
stantly contained in lactucarium ; the author convinced him- 
self of its presence in some I^actucarium anglicum, pro- 
cured in commerce, which on extraction with boiling water, 
treating the solution with basic acetate of lead, and de- 
composing the lead salt with sulphuretted hydrogen, yielded 
the acid in considerable quantity and in beautiful prismatic 
needles, and likewise citric and malic acids ; no succinic 
acid however could be detected in the lactucarium, of which 
two ounces were employed. 
To ascertain, moreover, whether the oxalic acid probably 
existed in the Lactuca as oxalate of lime, and could conse- 
vol. xi — no. i. 4 
