3G 
LACTUCA VIROSA AND SATIVA. 
barium and carbonate of barytes was collected and treated 
with dilute sulphuric acid, filtered, an excess of milk of lime 
added to the acid fluid, and filtered boiling. On evaporating 
the filtered solution some small crystals separated, character- 
ized by their being decomposed when heated in a glass tube 
with evolution of vapors, which excited coughing, and with 
the deposition of an acid sublimate. The residue from the 
treatment with milk of lime behaved therefore like citrate of 
lime, from which moreover a small quantity of pure citric acid 
was obtained in a crystalline state. For this purpose the lime 
salt was carefully decomposed with sulphuric acid, the filtered 
solution having however been previously examined for tartaric 
and oxalic acids. Chloride of calcium and chloride of am- 
monium added to a portion saturated with caustic ammonia 
produced no turbidness ; a portion to which a slight excess of 
caustic ammonia had been added, and then a solution of gyp- 
sum, exhibited, even after a long time, no change ; a sample 
rendered neutral, and boiled with chloride of calcium and 
caustic ammonia, immediately afforded a white pulverulent 
precipitate. 
The acid first obtained in prismatic tabular crystals was 
now submitted to a more accurate examination, and accord- 
ingly heated in a glass tube; it was entirely volatile, with evo- 
lution of abundant vapors, which excited coughing, and de- 
position of a sublimate resembling that of the lime salt already 
mentioned ; treated with chlorine and nitric acid, the crystals 
again afforded the same acid. 
The acid required 2 parts alcohol, 3 parts hot and 24 parts 
cold water, for solution. 
A sample was now dissolved in water, and tested with the 
reagents mentioned by Pfaff. It immediately caused a con- 
siderable brownish turbidness in neutral protosulphate of iron ; 
a solution of acetate of magnesia produced no change, which 
was likewise the case with sulphate or acetate of copper, which 
however were precipitated of a light blue color, when the acid 
was neutralized with caustic ammonia. The acid, dissolved 
