Dr. Stenhouse on Theine and its Preparation. 431 



Camellia does not contain any theine, and indeed its che- 

 mical properties have very little resemblance to those of the 

 tea plant. It has scarcely any of the bitter astringent taste by 

 which both green and black tea are distinguished, and it ap- 

 pears wholly devoid of any essential oil. It contains, how- 

 ever, a small quantity of tannin, which gives olive-green pre- 

 cipitates with salts of iron, and very copious yellow preci- 

 pitates with acetate of lead. It occasions a very slight 

 precipitate only in a solution of gelatine, and does not pre- 

 cipitate tartar-emetic at all. 



Besides tannin the Camellia also contains a quantity of 

 mucilage, some chlorophyle, and a waxy resinous matter. 



I have also examined the holly, the Ilex Aquifolium, 

 for theine, but without success. Its chemical properties ap- 

 peared pretty similar to those of the Camellia Jajponica. 



Action of Nitric Acid upon Theine. — As has been already 

 mentioned, when theine is boiled with three or four times its 

 weight of strong nitric acid, it is converted with copious evo- 

 lution of nitrous gas into a deep yellow liquid, which when 

 gently evaporated to dryness and slightly warmed, gives with 

 ammonia a purple colour similar to that of murexide. This 

 we have also mentioned is an excellent test for theine, and 

 it forms a very pretty class experiment. The yellow liquid 

 contains a very soluble crystalline body, which, when most of 

 the nitric acid has been driven off, and the solution evaporated 

 nearly to a syrup, crystallizes in long, hard, colourless needles. 

 They have a rather sweetish taste, and when freed from ad- 

 hering acid by repeated crystallizations, appear to be neutral 

 to test paper, or at least only very slightly acid. Both this 

 and the red colouring matter, however, appear to be the pro- 

 ducts of the imperfect oxidation of the theine. If the theine 

 is boiled for some hours in a great excess of nitric acid till a 

 drop of the solution, when evaporated to dryness, is no longer 

 yellow but white, the addition of ammonia does not produce 

 any change of colour whatever. Both the yellow liquid and 

 the substance which crystallizes in needles are then found to 

 have disappeared. If the greater portion of the nitric acid is 

 distilled off, and the liquor concentrated to a syrup as before, 

 it readily concretes on cooling into a mass, containing a num- 

 ber of large shining crystals. The mother-liquor which sur- 

 rounds them appears to consist chiefly of very deliquescent 

 ammoniacal salts. The crystals have a sweetish taste, grate 

 between the teeth, and have a bright silvery lustre. Their 

 crystalline form is not at all distinct, but they form large plates 

 which readily crystallize. They dissolve in about three times 

 their weight of cold water, but in a much smaller portion of 



