34 
LACTUCA VIROSA AND SATIVA. 
ART. IX— ON THE ORGANIC ACIDS OF LACTUCA VIROSA 
AND SATIVA, By M. Kohnke. 
Numerous doubts having been raised against the dis- 
tinctness of the so-called lactucic acid of PfafF ; the author 
has endeavored to settle these, and has found that the fresh 
plant contains no oxalic acid, but malic and succinic acids ; 
that, on the contrary, no succinic but oxalic acid occurs in 
the lactucarium. The author's experiments are as fol- 
lows : — 
Fresh entire plants of Lactuca virosa were cut into 
pieces, digested for several hours in warm water, boiled for 
a time, expressed and filtered, the solution precipitated with 
basic acetate of lead, the precipitate collected, washed, sus- 
pended while still moist in distilled water, and decomposed 
by sulphuretted hydrogen. The colored acid liquid ob- 
tained was evaporated at a moderate heat ; it finally con- 
gealed to a thick jelly. It had been ascertained by previous 
experiment that the acid was soluble in spirit, the gelatinous 
substance insoluble ; the mass was therefore treated with 
strong alcohol and warmed, when the latter substance se- 
parated in whitish lumps. This substance, after removal, 
dissolved with difficulty in water, very readily in dilute 
muriatic acid, from which solution it was thrown down as 
a voluminous precipitate on saturating the acid with caustic 
ammonia. It had a horny appearance when dried, a dirty 
yellowish color, and was now perfectly insoluble in water, 
and very sparingly soluble in dilute muriatic acid. 
The acid spirituous solution, which still appeared much co- 
lored, and but little of which color could be removed by 
treatment with purified animal charcoal, was mixed with water, 
the alcohol distilled off at a very gentle heat, and more water 
added to the residue, which was then saturated with carbonate 
of ammonia, which considerably decolorized the liquid and 
