wilds_of_virginia replied: "Methylene chloride is a toxin in the air. There are very tight restrictions on how much you can discharge. It is distilled to keep it out of the atmosphere, and also to reuse it in another batch of tea. -Wilds"

Chad replied: "It would have sublimed if it did not decompose. You pull a vacuum during distillations and sublimnations to make the temperature you need to achieve lower. Excessive heating of a compound often leads to decomposition."

A.V.R. replied: "There is some doubt about caffeine's effect on blood pressure. There is some study showing that caffeine intake increases the risk for those already having hypertension. There is, however, some studies that show that it does not have any long term risks for normal people. Isolation of caffeine from coffee: Coffee has more caffeine than tea. 1. Make a strong infusion of coffee preferably in an espresso machine. Allow to cool. 2. Take the infusion into a stoppered glass flask (conical or spherical). Add an equal volume of Trichloroethylene (TCE) Caution: Both must be at room temperature Avoid breathing TCE vapors 3. Close the flask, shake the flask enough to mix the two liquids. Caution: Vigorous shaking can cause TCE to build up pressure inside. 4. Periodically, slowly open the stopper just enough to leak out any TCE vapor that buils up. Open the stopper away from your face or any body else's nearby. Do this for about 5 minutes. 5. Pour the mix into a separating funnel. After the layers separate drain and separate the infusion from the TCE layer. Store the TCE extract in a flask for later use. 6. Repeat steps 2 to 6 using a new lot of TCE and the infusion separated in Five. Collect the second extract of TCE into the same flask containing the first extract. Discard the infusion. 7. Assemble a distillation column and distill off the TCE. The residue in the flask is the caffeine that was in the original coffee. This will be crude. May require redissolving in TCE , filtering and recrystallization. This can be done in an evaporating dish in a fume cupboard. I am afraid that, while this part may prove of interest, the other one about its effect on hypertension may be a disappointment. This will constitute human experimentation and is subject to various regulations. As pointed out earlier it may well be a wild goose chase. Better do the first part to show that caffeine can be isolated. Rely on literature search for the second part. Here is a list of publications on that:"

Colin replied: "When you heat the tea in water, you extract other things besides caffeine and these may cause frothing."

Chad replied: "Just keep in mind that without knowing the exp it is difficult to answer these questions.... 1. No idea what you used these for...NaHCO3 is generally used to basify solution and Na2SO4 to dry a solution. 2. Immiscible with water, heavier that water, organic solubile thing dissolve, easily removed...thats 4 off the top of my head. 3. 4. ...really. What happens if you poke a hole in the bottom of a beer (or coke Can) while you are drinking...the vacuum breaks and the fluid flows. 5. There is not enough information provided here to determine this."

Bob M replied: "it doesn't make sense"