117 



it the acid may be obtained by admitting sulphuret of hydrogen 

 and evaporating, towards the end of the ojieration, in a vacuum. — 

 It forms a colourless syrup-like liquid of 1'21 density, is in- 

 odorous, has a strong and pure acid taste, mixes with water and 

 alcohol in every proportion, dissolves less readily in ether, becomes 

 anhydrous = Cq H5 O5 at 1 30° and solidifies on cooling to a pale- 

 yellow mass of very bitter taste; it is decomposed in a higher 

 temperature. All the Lactates dissolve in water, though many of 

 them only sparingly in cold. 



Lactuceriu = C30 H24 O2. lu Lactucarium (the hardened 

 milky juice of Lactuca virosa and other species). Boil with 

 alcohol, filter hot and recrystallise the warty masses obtained, on 

 cooling, in alcohol with aid of animal charcoal; it is well to with- 

 draw first from the lactiicarium the bitter substance by means of 

 water. — Forms fine, colourless, concentrically united columnar 

 prisms, without taste or smell; neutral; fuses between 150° and 

 200°, sublimates mostly undecomposed in a current of carbonic 

 acid gas; is insoluble in water, soluble in alcohol, ether, and oils; 

 is not altered by jjotash dissolved iii alcohol; is not jirecipitable 

 from the alcoholic solution by metallic salts. 



Lactucill = C22 H12 Oe + HO. The bitter ingi-edient of Lac- 

 tucarium. Treat and press a few times with cold water and boil 

 repeatedly with water, evaporate the luiited liquids until equal in 

 weight to half the lactucarium employed, separate the substance, 

 settled to a gi-anular mass, from the mother-ley, and dissolve in 

 hot water, precipitate with subacetate of lead, wash the deposit with 

 hot water, adduce to the filtered liquid sulphuret of hydrogen, 

 filter again, evaporate and allow to stand cold. The Lactucin 

 forms in crystals, and by concentrating the mother-ley still further 

 an additional quantity will be obtained. Recrystallise in hot 

 alcohol with aid of animal charcoal. — Forms white, pearly scales, 

 similar to boric acid; fusible; becomes charred in higher tempera- 

 tures; has a strong and pure bitter taste; dissolves scarcely in 

 cold water-, in hot water less readily than in alcohol, not in ether, 

 readily in acetic acid; is decomposed by alkalies and loses its 

 bitterness. Is not glucosid. 



LactUCOU =:: Lactucerin, 



LadaillUU. Exudation of Cistus Creticus, and to some extent 

 also from C. ladaniferus, C. Ledon, C. laurifolius, and C. mon- 

 speliensis. — Black-brown, soft, of pleasant smell and of bitter taste. 

 Contains 86% resin, 7% wax, and some volatile oil. 



Laetia-Resill. Exudation of the stem of Laetia apetala. — 

 Small, yellow- white, translucid, brittle grains of concheous fracture, 

 and of faintly aromatic smell; slowly soluble in alcohol, yielding a 

 volatile oil when distilled with water. 



