428 Dr. Stenhouse on Theine and its Preparation. 



decoction should first be precipitated while hot with basic 

 acetate of lead. It should then be filtered and boiled with a 

 little hydrated oxide of lead, which occasions a further preci- 

 pitate, which is also to be separated by filtration. The clear 

 liquor is to be evaporated to dryness, and sublimed exactly 

 in the same way as the extract of tea. From a pound of 

 coffee, in the course of several trials, I obtained from 12 to 18 

 grains of theine, which was sometimes not so perfectly white 

 as that made from tea, as it was accompanied by a little more 

 empyreumatic oil. It was easily rendered perfectly pure 

 with scarcely any loss, by subliming it a second time at a very 

 moderate temperature. A considerable quantity of theine 

 may be easily made by sublimation, from either tea or coffee, 

 in the course of two days, while the ordinary way of procuring 

 it is both tedious and expensive. 



Several chemists have been induced to affirm that none of 

 the beneficial effects which tea and coffee produced on the 

 animal ceconomy, should be ascribed to the theine they contain, 

 owing to the smallness of the quantity in which they supposed 

 it to exist in these substances. Professor Liebig has, as is 

 well known, recently advanced the very opposite opinion, and 

 has rendered it highly probable that theine will yet be found 

 to possess valuable medical properties. I hope that some 

 medical practitioners may soon be induced to try if its utility 

 in medicine will be found equal to the expectations which 

 have been formed of it. 



In reference to the sublimation of theine, I may mention 

 that I have found it advantageous to make a slight addition to 

 Dr. Mohr's subliming apparatus, described in a previous 

 paper. Instead of pasting the diaphragm of bibulous paper 

 immediately on the rim of the iron pan, I paste it on a move- 

 able rim of tin plate about an inch deep, which goes close 

 round the outside of the pan, and which projects about one- 

 eighth of an inch within it. When covered with the paper it 

 exactly resembles a small sieve, and may be easily removed 

 and replaced at pleasure. This enables us to stir the mass 

 we may be subliming from time to time, and thus to heat the 

 whole of it more equally. Now this could not be done in the 

 usual apparatus without destroying the diaphragm. 



Theine in Paraguay Tea. — I am indebted to the kindness 

 of Professor Christison for a quantity of Paraguay tea, or 

 " yerba mate," as it is called. It consists of the leaves and 

 small branches of the Ilex paraguayensis, which after being 

 strongly roasted, have been reduced to a coarse powder. 

 This substance is extensively used in South America as a 

 substitute for tea. Its taste is very bitter, partly resembling 



