Dr. Stenhouse on Theine and its Preparation. 429 



that of ordinary tea, but also approaching somewhat to that 

 of sumach. Its reactions were studied a number of years ago 

 by Professor Tromsdorff, and are pretty fully stated in the 

 eighteenth volume of the Annalen der Pharmacie, page 90. 

 As my own observations coincide pretty closely with his, it 

 appears unnecessary to give a detailed account of them. In 

 proceeding to examine Paraguay tea for theine, acetate of 

 lead was added to its decoction, which threw down a very 

 dense greenish-yellow precipitate, and when this was removed 

 by filtration, subacetate of lead also produced a considerable 

 quantity of a bright yellow precipitate. The clear liquid 

 when drawn off' and evaporated to dryness, left a good deal 

 of a tenacious dark brown mass, which was very hygroscopic. 

 When a little of it was subjected to distillation, a quantity of 

 long flat crystals, exactly resembling the theine, sublimed 

 into the sides and neck of the retort; and at the same time 

 the very peculiar pungent smell which theine always emits 

 when subliming became very perceptible. 



The remainder of the brownish-yellow substances already 

 mentioned was reduced to fine powder, and intimately mixed 

 with a large quantity of sand to prevent its agglutinating. It 

 was then repeatedly agitated with aether in a stoppered bottle. 

 The aethereal solution when poured off and distilled pretty 

 low, deposited a quantity of crystals which were slightly 

 coloured at first, but which were rendered perfectly white by 

 repeated crystallizations. In their crystalline form, taste, so- 

 lubility in water, alcohol and aether, and in all their reactions, 

 they correspond exactly with ordinary theine. I may mention 

 also, as an additional confirmation of the truth of this opi- 

 nion, that in the course of some experiments upon theine, I 

 have found an excellent test for that substance, by which its 

 presence even in small quantities may be readily detected. It 

 consists in the action of nitric acid upon theine, the effects of 

 which are very different according to the quantity of the 

 acid employed, and the length of time during which its 

 action is continued. If theine is boiled for a ihw minutes 

 with only twice or thrice its weight of fuming nitric acid, 

 nitrous gas is given off in abundance, and a bright yellow 

 solution is obtained. If a little of this liquid is taken out and 

 gently evaporated to dryness in a porcelain basin, it leaves a 

 deep yellow mass. If a drop of ammonia is then let fall 

 upon it and a gentle heat is applied, a bright purple colour 

 is immediately produced, which cannot be distinguished by 

 the eye from that obtained from uric acid when similarly 

 heated. This rich purple colour is permanent, its aqueous 

 solution has a deep crimson shade. It also dissolves in 



