here's the soxhlet apparatus. it consists of a soxhlet, the bit in the middle. a condenser, the bit on the top. and the flask, the bit on the bottom.
here is what happens, once the flask is heated vapors travel up through the soxhlets sidearm up into the condenser, which condenses the vapors back into a liquid wherein they fall back into the soxhlet. the soxhlet is designed such that it will fill up with solvent and then drain itself almost completely back into the flask. it accomplishes this by starting a siphon once it begins to overflow through the small u shaped siphon tube you see on the side, this siphon will not break until it sucks air so naturally it empties almost completely. this process will cycle pretty much indefinitely as long as you provide heat and cool water to the condensor.
heres the pepper we are extracting, dried bih jolokia pods, i have hundreds of them, id probably have more if the plant didnt catch a virus or atleast what i think was a virus.
anyway, i tossed a bunch of these into a blender untill they were reduced to flakes
these flakes were packed into a glass thimble, which is basically a container with frited glass disk on the bottom that allows solvent to drain through. you absolutly do not need a thimble, alot of people just stuff a bit of loose cotton or glass wool into the base of the siphon tube. keep in mind tho that w/e you are extracting will float, so you need to get a plug of cotton on top of w/e you are extracting so that it will not float around
and now we fill the flask... with 200ml of n hexane, good and cheep non polar solvent. we use hexane because its non polar, a non polar substance is not misicible into water hence it will not extract water soluble stuff like chlorophyll and w/e else is is in plant tissue. im not the person to teach you why things are polar and why things are not, but i can tell you that it has to do with molecules dipole moment.
and now we apply heat! hexane boils quickly, at 70c. notice those little black bits on the bottom? those are boiling chips, i use them to get nice even safe boils. theres a phenomenon called "bumping" wherein you heat a liquid past its boiling point and it explosivly boils over at some trigger... like a bump. if you are lucky you just get a boil over into your distillate, if you are unlucky you get burned. you see 'bump flasks' on some apparatuses to stop contain this.
soxhlet filling up...
to many photos!
Edited by queequeg152, 06 December 2011 - 10:10 PM.