77 



Erytbropliyll, See Cissotannic Acid. 



Erytliroretiii. See Aporetin. 



Erytlirozyill. Peculiar nitrogenised matter of tlie root of 

 Riibia tinctorum. Treat one part madder on a linen clotli -with 

 nine parts water of 38°, mix tlie extract with an equal volume of 

 alcohol, collect the subsiding dark red-brown flocks and exhavist 

 with boiling alcohol, wash the remaining impure E. with cold 

 water until the latter is no longer pi^ecipitated by acetate of lead, 

 and dry on a watei'-bath.— Black, hard mass, difficult to pulverise, 

 burns with a horny odour, yields with water a thickish red- 

 brown fluid, but does not properly dissolve. 



EschSCholtzia Alkaloids. From the root and herb of 

 Eschscholtzia Californica Waltz obtained, besides a little chelery- 

 thrin, an acrid alkaloid and a bitter one. {a) Acrid alkaloid. 

 Exhaust with water and an admixture of acetic acid, throw down 

 chelerythrin and the acrid alkaloid with ammonia (the bitter 

 alkaloid remaining in sohition), wash the deposit, dry and dissolve 

 in ether, evaporate, dissolve again in water acidulated as before, 

 precipitate with ammonia, tfec; or remove the dyeing matters by 

 digesting with animal charcoal. — White powder, almost tasteless 

 by itself, but very bitter when dissolved in alcohol or ether ; 

 of alkaline reaction, insoluble in water, readily soluble in alcohol 

 and ether. Forms neutral, colourless salts, precipitable by the 

 hydrates and carbonates of alkalies and by tannic acid. Becomes 

 not violet with siilphuric acid, (b) Bitter alkaloid. After the 

 chelerythrin and the acrid base have been removed by ammonia 

 from the extract of the herb as above, the liquid is neutralised 

 with acetic acid, precipitated with tannic acid and otherwise 

 treated like Porj^hyroxin (from Sanguinaria). — Crystalline, 

 easily fusible mass of nauseous bitter taste and alkaline reaction, 

 imparts to concentrated siilphuric acid a beautiful violet colour, 

 which is obsei'vable even with a solution containing 1% of the 

 alkaloid by allowing one drop of the solution to float on the 

 sulphuric acid. 



Eseriii=PHYsosTiGMm, 



Essential (ethereal or volatile) Oils are compounds of car- 

 bon and hydrogen with or without oxygen, nitrogen, or sulphur. 

 Their distribution throughout the vegetable kingdom is so general 

 that it is difficult to single out a plant which does not, by its pecu- 

 liar odour, betray the presence of at least traces of volatile oils 

 contained either in the flowers, seeds, pericarps, leaves and barks, 

 or, though less frequently, in woods, and which oils often show a 

 marked difierence in physical and chemical properties when 

 obtained from difierent parts of the same plant. The taste of 

 these oils is generally hot and aromatic and their odour analogous 



